A large number of power meters have become commercially available during the last decades to provide power output (PO) measurement. Some of these power meters were evaluated for validity in the literature. This study aimed to perform a review of the available literature on the validity of cycling power meters. PubMed, SPORTDiscus, and Google Scholar have been explored with PRISMA methodology. A total of 74 studies have been extracted for the reviewing process. Validity is a general quality of the measurement determined by the assessment of different metrological properties: Accuracy, sensitivity, repeatability, reproducibility, and robustness. Accuracy was most often studied from the metrological property (74 studies). Reproducibility was the second most studied (40 studies) property. Finally, repeatability, sensitivity, and robustness were considerably less studied with only 7, 5, and 5 studies, respectively. The SRM power meter is the most used as a gold standard in the studies. Moreover, the number of participants was very different among them, from 0  to 56 participants. The PO tested was up to 1700 W, whereas the pedalling cadence ranged between 40 and 180 rpm, including submaximal and maximal exercises. Other exercise conditions were tested, such as torque, position, temperature, and vibrations. This review provides some caveats and recommendations when testing the validity of a cycling power meter, including all of the metrological properties  and some exercise conditions . Power output (PO)  measuremRecently, many systems have become commercially available to provide the PO measurement based on ergometers, home-trainers or mobile systems mounted on personal bikes. Due to the large interest in measuring PO, the list of systems available for this purpose is very exhaustive . The validity of power meters is of interest to different potential users. For example, mobile power meters were mainly used by professional cyclists for nearly 25 years. Today, we can observe that all of the WorldTour men’s teams are using power meters, 10 use Shimano power meters, whereas six different power meters  were used by the remaining nine teams. In addition, based on the popularity in the highest level, mobile power meters are actually used by many recreational cyclists. Due to the large number of potential users, manufacturers developed systems and established claims regarding their system’s validity. The validity of power meters has also been tested in scientific research to provide more details regarding their metrological properties . However, a major problem is that not all of the metrological properties are investigated in most of the studies. Indeed, the studies included only some properties of the power meters and did not provide very relevant information for the end user. Moreover, it is not always easy to make the link between the statistical analyses and the metrological properties studied.Some misunderstandings are notable from the technological description of systems leading to inappropriate protocols or mistakes during measurement. It is important to clearly understand what is really measured by these systems and the technology used to stress these systems, as well as incorporate all of the recommendations from the manufacturer as calibration and/or offset processes to obtain meaningful data. For example, the SRM system has become the gold standard for power meters to assess the validity of other mobile power meters ,37,38 orPrevious studies have proposed several conditions to assess the validity of power meters by studying different metrological properties implementing different protocols, data analysis, and testing the responses of the systems according to different exercise conditions  that can directly affect the results and conclusions. No study provides a clear overview regarding the validity of the power meters in all of these conditions. Our own experience over the last decade in power meter testing pointed out that testing situations, methods or environmental conditions, such as temperature or vibration can lead to misinterpretation of confidence that we can get from the devices. Therefore, this review aims to provide caveats and recommendations to assess the validity of cycling power meters, while taking into account all of the metrological properties that should be studied.When performing measurements with power meters, it is legitimate to question the validity of the meters. Validity is commonly defined as the degree to which the devices measure what they are expected to measure ,48,49. ASensitivity can be determined as the smallest measurement change that can be detected by the power meter. It is also the ability to detect changes in performance, which may be very small but still meaningful to athletic performance . SensitiRepeatability refers to the variation in repeating measurements with the same power meter under similar conditions . RepeataReproducibility refers to the variation in measurements made on a power meter under changing conditions ,54. The Both reproducibility and reliability can also be described in the literature by “reliability”. We can find this terminology in different situations in order to present with-in session reliability as repeatability or with-in device reliability as reproducibility and many other conditions as cadence, ageing, etc.Finally, robustness is the ability of power meters to remain unaffected by small variations in experimental factors . TherefoIn order to identify the articles that are focused on the validity of power meters and to manage this review, we used the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) methodology ,58. ThisThe main eligibility criteria include all of the studies or conference papers that aim to investigate the metrological proprieties  of cycling power meters or ergometers measuring PO for sport, medical or research purposes. Studies were included if (1) they are written in English; (2) they provide a clear methodological content with statistical approaches and gold standard device or method; (3) the full text was obtained to permit effective screening.A Boolean/phrase search mode was used in the search engine in all of the fields with the following keywords: “Cycling power meter” OR “ergocycle” OR “ergometer” AND “validity” OR “reliability” OR “accuracy” OR “sensitivity” OR “repeatability” OR “reproducibility” OR “robustness” in three different search engines: PubMed, SPORTDiscus, and Google Scholar. The research ended on 10 November 2021.The data extraction process was performed in duplicate on a Microsoft Excel spreadsheet  and 4111 items were collected. All of the duplicated references were removed to obtain 2939 items. Based on the criteria described previously, two reviewers (A.B. and J.C.) pre-screened the title and summary in order to obtain a list of the full texts that should be included in the screen list. The screening, which was operated by J.C. and A.B., yielded six additional references from the reference list of screened full texts.An important review of the literature listed many studies (74) that were aimed at assessing the validity of PO measurement devices . This reAmong the 74 studies listed, 33 examined the validity of ergometers. The majority of medical bikes measured PO based on the flying wheel resistance, pedalling cadence, and gear. Friction-braked , air-braked  or electromagnetically braked ergometers  can apply theoretical brakes computed from the rotation speed of the flying wheel. The angular velocity of the wheel is different from the pedalling cadence depending on the gear, which is why manufacturers integrate this element into the calculations. For those kinds of bikes, mechanical brakes with a friction belt on the flywheel  are very popular, but suffer from many limitations due to the frictional loss as well as the pendulum error of measurement. Ergometers with electromagnetic brakes are probably the best represented category with many medical brands, such as Shiller, Ergoline, Custo, Lode, General Electric, etc. In addition, very few studies report information regarding the validity of these bikes for several reasons. First, it was not easy to install a gold standard system on these ergometers in order to perform simultaneous measurements. Second, these bikes were designed to assess patients and do not fit a cyclist’s requirements for the rider position, saddle, and pedals.The main findings of this review show that various technology and heterogeneous protocols were reported among the studies, including different metrological properties, gold standard systems, statistical analyses, and exercise conditions. The following sections will discuss the technological description of power meters, protocols, and data analysis, as well as exercise conditions.Mobile power meters can use different technological components to obtain PO. Regarding force, the systems available on the market mainly use strain gauges, and also resonant string gauges. Regarding angular velocity, manufacturers mainly use magnetic sensors to count the number of passages in front of magnet(s). According to the design of systems, various numbers of magnets are used to obtain a higher sampling frequency on a single revolution . Finally, several devices measure angular velocity with accelerometers . Technological conception is very important since each element will be affected by exercise conditions.Strain gauges can transform micro-strains into electric resistance variation . Those sRegarding angular velocity, the majority of systems measure the time elapsed during a revolution or part of a revolution if several magnets are used. The number of magnets affects the sampling rate of angular velocity and can be a limiting factor during a low rate. In addition, several manufacturers use multi-pole magnets (North–South) to obtain double-point measurements . A higher number of magnets permits the detection of the angular position of sensors to provide a pedalling pattern when computed with the torque. Then, the angular velocity can be determined with an accelerometer . This technology makes it possible to obtain an angular velocity on each point of the revolution. Manufacturers use this advanced technology less due to data filtering. In addition, processing is very important and leads to some limitations. Finally, for a very important pedalling cadence or vibration, systems can be saturated and produce erroneous data.In this review, 74 studies compare PO measurement systems with gold standard systems to investigate system accuracy . Neverth2) measurement, could not clearly indicate the level of validity. In those situations, the differences are related to the PO measurement system, participants or metabolic measurements. Using a large sample, overestimation or underestimation can be described if the difference is large enough.In addition, some studies compared different ergometers using metabolic measurement devices ,61,82. GFrom our point of view, only the simultaneous PO measurement with a system and a gold standard can permit the evaluation of the accuracy of a power meter. In this situation, it is possible to provide quantitative information regarding accuracy. Regarding statistical methods, the Bland and Altman ,124 methMoreover, instantaneous PO values are cyclic due to the different force moments and effectiveness during the pedalling cycle . Even duThese elements led to an inability to perfectly synchronize many systems and placed important limitations on a statistical approach when analyzing the 1-s peak PO. PO values follow a sinusoidal curve. A shift in synchronization automatically leads to the average PO for different periods and finally produces different average values. For example, At the same time, many studies compared the PO measurement with average values delivered by two sensors. The duration of the averaging period can be very different from one study to another. The period length ranged from 1 s, 5 s , 10 s 8, 15 s 3, 30 s 7, and 1 mTo standardize studies regarding the PO measurement, the averaging period seems to be a very important method that permits the comparison of power meters. A small averaged period can be interesting to compare systems and obtain information regarding the sensitivity of PO variations. Nevertheless, a systematic bias due to a synchronization shift should be avoided when comparing data. In this context, a 5-s duration appeared to be a relevant period for sub-maximal intensities since users often use smoothing to display the PO data on a bike computer (the average was 3 or 5 s). This duration provides less variation in the power control display that allows for the target PO to be maintained more easily during the effort.Averaging periods longer than 5 s lead to a smaller LoA . This apAll of the metrological properties of the power meters have been analyzed using many statistical methods in the literature. It should be noted that the studies reviewed in Different methods are used in validity studies of power meters . The cirt-test would be used to compare the mean values between two different power meters  or between test and retest sessions (repeatability and reproducibility) to analyze whether there is any statistically significant bias between the power meters or tests. Although the paired t-test is useful, it should not be employed on its own as an assessment of all the metrological properties. Bland and Altman [t-test for assessing accuracy, since the detection of a significant difference is actually dependent on the amount of random variation. For conducting more measurement sessions, the analysis of variance (ANOVA) is needed. ANOVA with repeated measures has been used to assess systematic bias between several measurements with appropriate post hoc comparisons. However, the limit of this statistical analysis is similar to the limits of the paired t-test. The systematic bias is affected by a large random variation.The paired d Altman  stressedAltman and Bland  introduct-test, a wide range of individual differences may lead to false acceptance of this hypothesis.The correlation coefficient is used by some authors for assessing the accuracy between two power meters ,66,67,70The coefficient of variation (CV) is also used to determine if the measurements are repeatable and reproducible . It is iIntraclass correlation coefficient (ICC) is also a common method for assessing repeatability and reproducibility ,109,140.d, which represents the ratio of the mean difference over the pooled variance to estimate the magnitude of the difference. As Cohen [Finally, in studies that compare different power meters to assess accuracy, the effect size (ES) represents the magnitude of the difference between power meters. The absolute ES is the difference between the average or mean outcomes between the two different power meters . While tAs Cohen  proposedDue to technological differences, integrated components or measurement location, many exercise conditions can alter the PO measurement, including PO range, sprint, pedalling cadence, torque, position, participant, temperature, vibration or field test. The following paragraphs aim to describe some of the problems that occur with those exercise conditions and explain why it is necessary to assess them.The range measurement is the area determined by minimal or maximal values of the variable to be measured . For example, the SRM power meter has a range measurement between 10 and 2500 W, which allows the valid measurement of PO during low-intensity  and high-intensity  exercises. This paragraph does not take care of the maximum PO during sprints, since those cases will be managed separately in another paragraph.Testing many PO ranges is necessary to confirm that a system can provide valid data in a PO range, in which the system is supposed to be used according to the population and need. As an example of rehabilitation, tools or medical devices should be tested from 0 to 300 W and systems aiming to test elite athletes should be tested from 0 to 600 W during a steady state of at least 1 min. Higher values are not supposed to arise during the steady state measurement and will be managed in the sprint section. Many studies aimed to investigate PO systems using an incremental protocol to obtain comparisons of different PO values ,51,77. WSeveral studies reported problems in the linearity of measured PO with drifts in validity and larger LoA in higher values ,86,140. Sprint tests are widely used in cycling to assess the anaerobic capacities of athletes ,147, andPO is commonly obtained by measuring both angular velocity and torque. For each PO range, an athlete or patient can vary these two parameters to adjust their PO with cadence or resistance. Pedalling cadence during a constant PO exercise bout can be very different for rehabilitation purposes (15–100) ,160 or pTorque measurement is one part of the calculation. Unlike pedalling cadence, torque is a little more difficult to manage for the same PO range, given that it depends on the sensor sensitivity and location. Nevertheless, several authors created protocols that induce different ranges of torque. Bertucci, Duc, Villerius, Pernin, and Grappe  created The effects of position on PO measurements have been tested in several studies ,94,106 tThe number of participants and their characteristics are very important for integrating the results that were obtained. Some studies used only one participant during the measurement process ,77,88,89The use of strain gauges allows for the accurate measurement of torque, but they are sensitive to changes in ambient temperature ,177, whiThe effect of vibration on PO measurements has been tested in only three studies ,114,115.These results can suggest that the robustness of the Stages and Garmin Vector and Favero Duo could alter the validity of the PO measurement on roads with cobblestones or with high macrotexture surfaces. In addition, the decrease in PO measured by Stages and Garmin Vector and Favero Duo could be due to the use of accelerometers to measure angular velocity. The accelerometers could be out of their range of measurement, especially when the road conditions involve a severe vibration exposure from 30 Hz or 48 Hz. The Stages and Garmin Vector power meters cannot be considered suitable for practice with strong vibrations, such as mountain biking and cobblestone roads. The study of Bouillod, Pinot, Soto-Romero, Bertucci, and Grappe  highlighAll of the studies analyzed the PO systems in several steady-state periods. During those steady-state periods, small variations in PO are observed around target values. This situation can permit a PO range to be associated with a specific accuracy. Nevertheless, this protocol offers a situation with very low PO variation and without free wheel periods, as in natural-use scenarios. A recent study  showed tThe procedures and methods used in the studies to assess the validity of power meters are very different, including the protocols, statistical analysis, data processing or interpretation. These differences are mainly due to a lack of consensus in the literature to evaluate these tools. As described in this review, the methods used to assess power meters largely affect the results and make the comparisons between the studies and devices impossible. This review provides some caveats and recommendations to assess the validity of cycling power meters, such as including all of the metrological properties . In addition, several exercise conditions that could affect the validity have been noted. All of these metrological properties and exercise conditions have to be tested to assess the validity in any situation. However, given the large number of these metrological properties and exercise conditions, the studies can be performed with only some properties, if not all of them are required . If some properties are not tested, they should be mentioned in the Study Limitation Section. To provide relevant information to the readers, it is recommended to compare a device with a gold standard system using similar time measurements. In addition, the PO range has to fit the requirements of a population that use these systems . Moreover, the inclusion of a large number of participants (at least 10) is highly recommended, in order to limit the effects of individual characteristics on validity. Finally, the protocols aimed at evaluating sensors during anaerobic tests (or sprints) should be performed to obtain specific data, similar to the maximum PO or times to reach a maximum PO. Furthermore, the performance of at least three trials for each sensor and the evaluation of the reproducibility or repeatability between the sensors are also recommended.


Regression models revealed a relationship between the MRC score and sEMG and torque measures for both the TB and BB. The results confirmed that variation on the MRC strength scale is associated with variation in sEMG and torque measures, especially post intervention. The regression model showed a causal relationship between MRC scale scores, sEMG, and torque assessments.It remains unknown whether variation of scores on the Medical Research Council (MRC) scale for muscle strength is associated with operator-independent techniques: dynamometry and surface electromyography (sEMG). This study aimed to evaluate whether the scores of the MRC strength scale are associated with instrumented measures of torque and muscle activity in post-stroke survivors with severe hemiparesis both before and after an intervention. Patients affected by a first ischemic or hemorrhagic stroke within 6 months before enrollment and with complete paresis were included in the study. The pre- and post-treatment assessments included the MRC strength scale, sEMG, and dynamometry assessment of the triceps brachii (TB) and biceps brachii (BB) as measures of maximal elbow extension and flexion torque, respectively. Proprioceptive-based training was used as a treatment model, which consisted of multidirectional exercises with verbal feedback. Each treatment session lasted 1 h/day, 5 days a week for a total 15 sessions. Nineteen individuals with stroke participated in the study. A significant correlation between outcome measures for the BB (MRC and sEMG  The primary aim of the post-stroke rehabilitation process is to restore and maintain the patient’s ability to perform actives of daily living. Importantly, this process starts within the first days after stroke and often continues over many years . BecauseThe status or change of a clinical condition is traditionally assessed by completing assessment scales. The validity and reliability of these assessment scales are essential to monitor a patient’s recovery and are critical for determining appropriate therapies. A common and widely accepted assessment scale for muscle strength is the Medical Research Council (MRC) scale ,6. This Muscle force can be directly measured with a dynamometer, an electromechanical device that can be used to measure muscular strength of a maximum isometric contraction for most major joints in the human body ,14. BascThe sEMG is a non-invasive technique for recording the electrical signal generated by muscular activity . DecodinThus, in this study we examined whether the scores of the MRC scale are associated with instrumented measures of muscular force and muscle activity pre- and post- an intervention for severe hemiparesis in post-stroke survivors.Proprioceptive-based training (PBT) was used as a treatment model; PBT is a neuromodulatory treatment modality that has been proposed for the treatment of the upper limb to recover voluntary muscle contraction and strength in stroke survivors .This study was conducted in the neurorehabilitation hospital and research institute of San Camillo IRCCS . Inpatients affected by first ischemic or hemorrhagic stroke within 6 months before enrollment in the study and with an MRC score at baseline between 0 and 1 point for their biceps brachii and triceps brachii were included in this study. The presence of hypertonia, apraxia, global sensory aphasia, neglect, cognitive impairments, severe sensitivity disorders, stroke lesion located in the cerebellum, or refusal to participate resulted in exclusion from the study.The local Ethics Committee of the IRCCS San Camillo Hospital approved this study (Protocollo 2012.07 BAT v.1.2), which was registered on ClinicalTrials.gov (NCT03155399). Informed, written consent was obtained prior to participation in the study.The MRC scale for muscle strength, dynamometry measures of maximal elbow flexion and extension torque, and sEMG measures of biceps brachii and triceps brachii activity were implemented pre- and post-intervention. The positions of the upper extremity for dynamometry measurements and for the MRC scale assessment were the same. An elbow splint was used to standardize the position of the patient’s arm during sEMG signal acquisition; the elbow joint was fixed to 40° for assessment of the biceps brachii and 90° for the triceps brachii.Testing was performed by a physiotherapist after assessment of elbow range of motion. The physiotherapist ensured that the wrist flexors were not contracted when assessing biceps brachii and provided stabilization support with a hand placed above the patient’s elbow when assessing triceps brachii. All patients firstly underwent an assessment of the biceps brachii followed by assessment of the triceps brachii. The assessment of biceps brachii was performed in the supine (or in sitting in the case of grade 2 or more) position with the forearm supinated and elbow flexed to approximately 45 degrees as the patient was asked to “bend your elbow” . The assAn electrical dynamometer (CITEC Hand-Held Dynamometer) was used for testing. The participant’s positions for assessment of maximal elbow flexion and extension torque were adopted from the MRC scale evaluation. The biceps brachii was assessed first in all participants. Patients were asked to perform three attempts with verbal encouragement to exceed the previous score and the mean value was considered for analysis.The sEMG was acquired with bipolar electrodes from the long head of the biceps brachii and the lateral head of the triceps brachii, according to published guidelines for electrode placement  after skThe sEMG was acquired during maximal voluntary isometric contraction (MVC) of elbow flexion and extension, each repeated three times. The sEMG was recorded with the following procedure: recording of baseline activity at a resting state followed by the task itself  recorded for 2 s each. The peak values of the amplitude of the envelopes of the sEMG of baseline and during the MVC were extracted, and the difference was computed. The mean value from the three repetitions was considered for further analysis.Participants underwent PBT, which consisted of multidirectional exercises executed synchronously with the unaffected limb and verbal feedback. Patients were asked to move both upper limbs synchronously performing bilateral flexion-extension at the level of their elbow joint. The PBT therapeutic session was divided into the following repetitive phases: proprioceptive stimulation for 3 min with a rest of at least 2 min between stimulations and repeated at least three times for each muscle. Additionally, all participants received individual exercises  for postural control in sitting or standing position. The training protocol lasted 1 h a day, 5 days weekly for a total of 15 sessions .p < 0.05. All calculations were performed using R Statistical Computing software.Data distribution for all the variables was tested through the Shapiro–Wilk test. The Spearman’s rank correlation test was used to study potential associations between the MRC scale score and measures of elbow flexion and extension strength and sEMG amplitude of the biceps brachii and triceps brachii muscles both pre- and post-intervention and on the change scores (before–after intervention). A regression model was implemented on the post intervention data to verify the relationship between the MRC strength scale scores and dynamometry measurements of elbow flexion and extension strength and sEMG amplitude of the biceps brachii and triceps brachii. We assessed the MRC models fitting as follows: the overall significance of the regression model with the percentage of variance explained (% Variance explained); the variance of the residuals ; the normality of the residual distribution ; the presence of outliers . Bland–Altman graphs were reported to evaluate the agreement between the measurements made with MRC and those made with sEMG and dynamometry. The statistical significance level was set at Data from 19 patients with a mean age of 61.48 ± 12.77 years  were analyzed in this study. Patients’ mean time from stroke onset was 3.19 ± 1.80 months. Twelve patients had ischemic stroke and seven had a hemorrhagic stroke (8 right and 11 left lesion side). Descriptive characteristics of the parameters measured before and after intervention are presented in p = 0.0000; triceps brachii p = 0.0002)  and triceps brachii   , whereas 0.0001) .A generalized regression model was used to study the relationship between the MRC scale scores, sEMG amplitude, and dynamometry measures of maximal elbow flexion and extension torque. The regression model showed that an increase of muscular strength by one point on the MRC scale was related to an increase of 59 mV (millivolts) of biceps brachii sEMG amplitude  and for those estimated with dynamometry (W = 0.93 p = 0.17). On the other hand, the goodness of fit carried out on the models of MRC triceps brachii did not have a normal distribution of residuals for the model estimated with sEMG (W = 0.83 p = 0.009) or for the model estimated with dynamometry (W = 0.89 p = 0.03). In all the Residuals versus Fitted graphs (The goodness of fit of the first and second models showed normal distribution of residuals, whereas the goodness of fit of the third and fourth models showed non-normal distribution . The QQ d graphs , the poid graphs  highlighd graphs .The results of this study showed that for the post-intervention data, muscular strength measured by the MRC scale was correlated to both the amplitude of muscle activity measured by sEMG, as well as measures of maximal voluntary torque assessed with dynamometry. Thus, the clinical measure of muscle strength in patients with hemiparesis increased in accordance with the changes observed in sEMG and dynamometry measures. We also observed that the MRC scale score and dynamometry measures were correlated when examining the pre-intervention data, but a similar correlation was not present between the MRC scale score and sEMG measures pre-intervention. This is likely due to the severe weaknesses of the tested muscles pre-intervention, which mostly did not present an active voluntary contraction.In a study by Deroide et al., which investigated patients with neuropathic conditions, the EMG at baseline and during a MVC were weakly but significantly correlated to the MRC score . ConsideDirect measurement of muscle force using sEMG is not possible, and, although some studies have reported a linear relationship between force and sEMG amplitude , severalThere are some methodological considerations to note when interpreting the findings of this study. Firstly, we enrolled post-stroke patients with severe upper limb hemiparesis and, consequently, the presence of muscular fatigue and hypo-tone introduced non-linear distortions to the force–sEMG relationship, which may have limited this study ,49. A fuConsidering that the inter-rater reproducibility of the MRC scale had several limitations , future Variation in scores on the MRC scale was associated with variation in electromyographic activity as well as elbow torque measured with dynamometry. The findings of this study can be used to ensure more precise clinical assessments of patients with stroke.


We report a case of decompensated Wilson's disease presenting with fulminant hepatic failure treated with an emergent living donor liver transplant. A 25-year-old female presented with fulminant hepatic failure and underwent an emergent living donor liver transplant using a left-lobe graft from her brother. Explant revealed a nodular, cirrhotic liver with numerous yellow-green nodules on the cut surface, and histopathology revealed confluent necrosis and cholestasis with positive copper immunostain. Quantitative hepatic copper was 2119 mcg/g (range: 10−35 mcg/g). Recipient genetic testing revealed c.2930C>T p. (Thr977Met) homozygous variant in the ATP7B gene. The donor was heterozygous for the mutation. The recipient continues to do well three years later with normal ceruloplasmin and urinary copper excretion.Emergent living donor liver transplantation in adults with fulminant hepatic failure secondary to Wilson's disease is rarely performed. Wilson's disease is an autosomal recessive disorder of copper metabolism caused by a mutation in the ATP7B gene on chromosome 13. It affects one in 30,000 individuals with a reported carrier frequency of one in 90 . We repoThis report was presented as an abstract at the Annual Scientific Meeting of the American College of Gastroenterology in October 2019.A 25-year-old female with no prior medical history presented with jaundice and fatigue with laboratory studies demonstrating marked hyperbilirubinemia and coagulopathy. Serum ceruloplasmin level was low: 70 mg/L (range: 190-390 mg/L), and 24-hour urine copper was markedly elevated at 7269 μg/24 h (range: 5-50 μg /24 h). The subsequent clinical course was characterized by progressive encephalopathy and coagulopathy, with a model for end-stage liver disease score (MELD) > 40. Initial and subsequent laboratory test results are outlined in Table Diagnosed with fulminant hepatic failure due to Wilson's disease, she underwent emergent living donor liver transplantation utilizing a left-lobe graft from her 33-year-old brother, who had normal screening ceruloplasmin. The explant revealed a nodular, cirrhotic liver with numerous yellow-green nodules on the cut surface Figures , 2.Histopathology revealed confluent necrosis and cholestasis with positive copper immunostain Figure .Quantitative hepatic copper content was 2119 mcg/g (range: 10−35 mcg/g). Recipient genetic testing revealed c.2930C>T p. (Thr977Met) variant in homozygosity in the ATP7B gene. Donor was noted to be heterozygous for the mutation. The patient gradually improved and continued to do well 36 months later with excellent allograft function, normal ceruloplasmin, 24-hour urinary copper excretion, and no evidence of neurological manifestations of Wilson's disease.The introduction of copper-chelating agents such as D-penicillamine and trientine hydrochloride has greatly improved the outcomes of patients with Wilson's disease presenting with chronic liver disease. However, liver transplantation remains the only viable therapeutic option for those presenting with decompensated cirrhosis and fulminant hepatic failure .The overwhelming majority of reported cases of emergent liver transplantation for fulminant hepatic failure secondary to Wilson's disease in adults utilized deceased donor liver transplants, with a few reported cases of living donor liver transplants in children . Given tHowever, in countries where deceased organ donation is limited, the only option, given the time-sensitive need for transplantation, is the consideration of emergent living donor liver transplantation. Since a majority of living donor liver transplants are performed using related donors, the possibility of donor heterozygosity remains a concern. In this instance, there was a significant concern for donor heterozygosity since the living donor was the brother of the recipient. Encouragingly, in prior reports analyzing recipients with cirrhosis secondary to Wilson's disease, both short-term and long-term outcomes following living donor liver transplant using donors that were heterozygous for the Wilson's disease gene were comparable to those from deceased, unrelated donors ,5. LivinGiven the scarcity of deceased donor organs, living donor liver transplantation may be a safe and effective option in decompensated Wilson's disease presenting with fulminant hepatic failure, even if the donor could potentially be heterozygous for the Wilson's disease mutation. Further study is needed to evaluate the long-term impact of potential donor heterozygosity on outcomes following liver transplantation for Wilson's disease.


Obesity and its related complications are a world-wide health problem. Dietary tocotrienols (TT) have been shown to improve obesity-associated metabolic disorders, such as hypercholesterolemia, hyperglycemia, and gut dysbiosis. This study examined the hypothesis that the antioxidant capacity of TT alters metabolites of oxidative stress and improves systemic metabolism. C57BL/6J mice were fed either a high-fat diet (HFD control) or HFD supplemented with 800 mg annatto-extracted TT/kg (HFD+TT800) for 14 weeks. Sera from obese mice were examined by non-targeted metabolite analysis using UHPLC/MS. Compared to the HFD group, the HFD+TT800 group had higher levels of serum metabolites, essential amino acids (lysine and methionine), sphingomyelins, phosphatidylcholine, lysophospholipids, and vitamins . TT-treated mice had lowered levels of serum metabolites, dicarboxylic fatty acids, and inflammatory/oxidative stress markers  compared to the control. The results suggest that TT supplementation lowered inflammation and oxidative stress (oxidized glutathione and GSH/GSSH) and improved macronutrient metabolism (carbohydrates) in obese mice. Thus, TT actions on metabolites were beneficial in reducing obesity-associated hypercholesterolemia/hyperglycemia. The effects of a non-toxic dose of TT in mice support the potential for clinical applications in obesity and metabolic disease. Obesity is characterized by an excessive amount of adipose tissue, which has been recognized as a major endocrine organ that releases a wide variety of signaling molecules  ,2. TheseObesity is accompanied by a state of chronic low-grade systemic inflammation that accelerates the development of insulin resistance in type 2 diabetes (T2DM)  and hypeStudies in cell cultures, animal models, and human participants have provided compelling evidence that vitamin E, mainly tocopherols, play a role in preventing T2DM due to their antioxidant and anti-inflammatory capacities . Until rTocotrienols have received increased attention due to their ability to attenuate obesity-associated complications via various molecular/cellular mechanisms, such as induction of apoptosis in preadipocytes, inhibition of fat cell adipogenesis and differentiation, activation of energy sensing pathways, protection of cell membranes against oxidative damage, inhibition of lipid peroxidation, and suppression of inflammation ,14. In aThe present study used global non-targeted metabolomics to determine the metabolic effects of TT supplementation in mice with high-fat-diet (HFD)-induced obesity. Our approach focused on six broad pathways involving the metabolism of lipids, amino acids, cofactors and vitamins, nucleotides, peptides, and xenobiotics. We hypothesized that a diet supplemented with TT would reduce lipid peroxidation and oxidative stress, and alter the metabolism of amino acids, fatty acids, phospholipids, and sphingolipids in obese mice in ways that would be beneficial on lipid metabolism and glucose homeostasis in obese mice.Twenty male C57BL/6J mice , housed in cages of four mice and maintained at a controlled temperature of 21 ± 2 °C with a 12 h light-dark cycle, were fed chow diet and distilled water at libitum for 5 days. After acclimation, mice were weighed and assigned to two groups: control group fed high-fat diet  and the treatment group fed the HFD supplemented with annatto-extracted TT at 800 mg/kg diet (HFD+TT800). TT was extracted from annatto oil with 71.3% purity, containing 86.1% δ-TT and 13.9% γ-TT, free of tocopherol . The remaining 30% components of TT are mainly fatty acids of annatto oil itself, with a very small amount of plant terpenes, sterols, and waxes.TT was premixed with tocopherol-stripped soybean oil  before being incorporated into the ingredients of the HFD. Both groups were given the diets for 14 weeks with free access to water and diet during the study period. Previous rodent studies showed the anti-inflammatory actions of δ-TT at 400 and 1600 mg/kg diet/ in obese mice ; the TT g for 20 min to isolate serum. The serum samples were kept at −80 °C until further analyses.At the end of the experiment, mice were fasted for 4-h, anesthetized with isoflurane, and then euthanized. Blood was collected into microtainer blood collector tubes  and then centrifuged at 1500× m/z.Sample preparation and non-targeted metabolomics analysis of serum samples were conducted at Metabolon, Inc.  as described in a previous study . Brieflym/z), preferred adducts, in-source fragments, and associated MS spectra and curated by visual inspection for quality control using software developed at Metabolon, Inc. .Metabolites were identified by automated comparison of the ion features in the experimental samples to a reference library of standard chemical entries  that incPrincipal components analysis (PCA) and hierarchical clustering were used for classification analysis. For the scaled intensity graphics, each biochemical in original scale (raw area count) was rescaled to set the median across all animals and time-points as equal to 1. To gain insight into individual metabolites that may be able to differentiate the groups, we also performed random forest analysis. This method attempts to bin individual samples in groups based on their metabolite similarities and differences. The method is unbiased since the prediction for each sample is based on trees built from a subset of samples that do not include that sample . Random http://cran.r-project.org/ (accessed on 27 October 2016)) was used. Following log transformation and imputation of missing values, if any, with the minimum observed value for each compound, Welch’s two sample t-Test was used as significance test to identify biochemicals that differed significantly (p < 0.05) between experimental groups. An estimate of the false discovery rate  was calculated to take into account the multiple comparisons that normally occur in metabolomic-based studies.Two types of statistical analyses for metabolites were performed: (1) significance tests; and (2) classification analysis. Standard statistical analyses were performed in ArrayStudio on log-transformed data. For analyses not standard in ArrayStudio, the R program .p ≤ 0.05) with 44 additional biochemicals showing a tendency of change due to TT (0.05 < p < 0.1). Among the 68 biochemicals (p ≤ 0.05) with changes in concentration, 32 biochemicals edged higher whereas 36 others went lower. Similarly, among the 44 biochemicals (0.05 < p < 0.1), 18 biochemicals were higher whereas 26 others were lower.A comprehensive non-targeted mass spectrometry-based metabolomics profiling analysis was performed on sera from the HFD and HFD+TT800 mice after a 14-week feeding period. Overall, a total of 566 metabolites, or biochemicals, of known identity were detected and categorized into six broad categories including amino acids, cofactors and vitamins, lipids, nucleotides, peptides, and xenobiotics. Among these 566 compounds, 68 biochemicals were primarily responsible for the observed significant difference due to TT . Other fatty acid dicarboxylates, including 2-hydroxyadipate, suberate, undecanedioate and hexadecanedioate, showed a trend of reduction (0.05 < p < 0.1). The HFD+TT800 group had lower levels of several fatty acid acyl glycine metabolites, including valerylglycine, hexanoylglycine, heptanoyl glycine, 3,4-methylene heptanoylglycine, and N-octanoylglycine, than the HFD group (p ≤ 0.05). In addition, the HFD+TT800 group had altered fatty acid acyl carnitine metabolites—lower hexanoylcarnitine (C6) levels and higher lignoceroylcarnitine (C24) levels—and a higher level of serum carnitine (p ≤ 0.05) /HFD, are presented in  ≤ 0.05) .Some oxylipins (bioactive lipids) were changed favorably in mice supplemented with TT, as shown by the (HFD+TT800)/HFD ratio . In thisp ≤ 0.05); and (ii) higher levels of glycerophosphorylcholine (GPC) and glycerophosphoinositol (GPI) (0.05 < p < 0.1).The effects of TT supplementation on sphingolipids, phospholipids, and other lipid metabolites are shown in p ≤ 0.05) and lysophospholipid intermediates . TT supplementation also led to higher ratios for the levels of 1--2-palmitoyl-GPC and 1--2-linoleoyl-GPC , 1-dihmo-linolenyglycerol , and glycosyl ceramide . TT supplementation led to lower levels of palmitoyl-linoleoyl-glycerol , mevalonate , and beta-muricholate .TT supplementation resulted in higher levels of phosphatidylcholine intermediates ; and (ii) food component metabolism . TT supplementation may have reduced the amount of these compounds by changing gut microflora in mice. Annatto seed is a medium to high source of salicylates, consistent with the higher level of salicylates found in sera of mice given TT800 as shown in panel The present study showed that 14 weeks of annatto-TT (90% δ-TT+10% γ-TT) supplementation significantly increased TT levels and reduced the intermediate metabolites of lipid peroxidation, dicarboxylic fatty acids  in mice fed a high fat diet. Dicarboxylic fatty acids are produced by fatty acid omega-oxidation, which can serve as a ’rescue pathway’ when beta-oxidation is impaired or overwhelmed  . The decSome oxylipins were changed favorably in mice supplemented with TT, and the ratio values of HFD+TT800/HFD for 13-HODE and 9-HODE, 14 HDoHe/17-HDoHe, and thromboxane B2 were lower, suggesting actions of lower acute pain and inflammation and auto-oxidation of DHA. The amount for 14 HDoHe/17-HDoHe showed a lower ratio which may support lower circulating triglycerides as we previously reported in male mice given TT with a high fat diet compared mice not given TT [Sphingomyelins are a class of phospholipids that are found in animal cell membranes and form lipid microdomains with cholesterol . The uniMice given TT compared to the controls in our study showed higher levels of PC, an abundant phospholipid of mammalian cells and subcellular organelles. There was a higher amount of complex lipid composition supporting phospholipid metabolism , PC  and lysophospholipid  in the TT-supplemented obese mice compared to the controls. These differences likely suggest that TT could play a supporting role in regulating lipid, lipoprotein, and energy metabolism.Allobaculum, Bifidobacterium, Eubacterium, and Anaerotruncus, while those of opportunistic pathogens  were increased, suggesting the role of TMAO in modification of gut microbiome during the development of T2DM [In our current study, TT-supplemented obese mice had significantly lower trimethylamine N-oxide (TMAO) in serum relative to the controls. TMAO has been shown in animal models to up-regulate macrophage receptors associated with atherosclerosis . Elevate of T2DM . In our  of T2DM , we repo of T2DM  along wi of T2DM ,9.Dietary supplementation with TMAO decreased the expression of a number of bile acid transport genes in the liver (Cyp7a1 and Cyp27a1) adversely affecting cholesterol elimination  and blocLysophosphatidylcholine (LPC) is an important signaling molecule with diverse biological functions . LPC is One of the earliest observed biological activities of TT is the ability to downregulate the mevalonate pathway via suppression of its rate-limiting enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) . Among tThe association of obesity, insulin resistance, and chronic oxidative stress/low-grade inflammation has been evident for more than a decade . The patp > 0.1) decreases in the ratios for oxidized glutathione (0.4056), cysteine-glutathione disulfide (0.7438), methionine sulfoxide (0.974), 5-oxoproline (0.949), and cystine (0.8775) were observed in TT-treated mice in relation to control mice. Reduction in these metabolites is reminiscent of an improved redox environment and might be an indication of lower oxidative insult by TT supplementation. In addition, lower activity of the γ-glutamyl cycle, which is important for recycling and regeneration of GSH, was noted in TT-treated mice, as evidenced by a decline in γ-glutamyl amino acids. Furthermore, compared to the HFD mice, the oxidative stress markers including oxidized lipids  and inflammatory molecule kynurenate were significantly reduced while an antioxidant marker threonate was significantly increased in the HFD +TT800 mice. Thus, the observed decrease in the levels of these oxidative stress markers provides added support for the notion that treatment with TT lowers HFD-induced oxidative stress.We previously reported TT supplementation improved glucose homeostasis (improved insulin resistance and decreased hyperglycemia) in obese mice via a reduction of inflammation and oxidative stress ,15. We sXanthine oxidase (XO) oxidizes hypoxanthine to xanthine and uric acid, producing hydrogen peroxide. A large body of work has demonstrated that enhanced XO activity is considered a damage signal, contributing to a damage-associated molecular pattern . EndotheA noticeable increase in vitamin B metabolites including pyridoxamine and pyridoxal was displayed by mice supplemented with TT. Vitamin B6 is an essential cofactor in various transamination, decarboxylation, glycogen hydrolysis, and synthesis pathways involving carbohydrate, sphingolipid, amino acid, heme, and neurotransmitter metabolism. Since the gut microbiota is associated with the biosynthesis of B vitamins, the observed fluctuation in vitamin B molecules in the HFD+TT800 animals could be linked to TT-mediated favorable alterations in microbiome composition . A conseThis global metabolomic profiling study was conducted to gain an understanding of the changes in metabolites associated with TT supplementation in HFD-induced obesity in mice. Overall, the results from the serum profiling demonstrate alterations in biochemical pathways, including those of amino acids, lipid oxidation and peroxidation, oxidative stress, sphingolipids, and xanthine oxidase along with changes in serum metabolites that may be related to the intestinal microbiome. As a path forward, it is important to measure metabolic changes under TT treatment using a complex lipid platform which will shed light on the comprehensive changes in lipid metabolism with TT supplementation. Additionally, research on adipose tissue adipokines and composition of fatty acids in obesity should reveal the role of TT in inflammation and fatty acid metabolism in regard to oxylipins and endocannabinoids. Finally, the level of TT used is well within the safety range of TT , suggest


Bacterial meningitis is one of the critical diseases that needs to be diagnosed and treated promptly. Recent diagnostics of high sensitivity and specificity rates, such as PCR, helped with such presentation, especially in cases with prior antibiotics that led to culture negativity. However, the time window of PCR positivity is not well-studied, with scattered reports of different periods of positivity. Here, we report a case of neonatal GBS meningitis with positive PCR for more than 80 days from starting antibiotics. Streptococcus agalactiae, [Group B Streptococcus (GBS)], is a part of the normal gastrointestinal and vaginal flora and is considered the leading cause of invasive infection in neonates and early infancy, causing a spectrum of clinical syndromes including bacteremia, meningitis, urinary tract infection, and pneumonia  culture remains the gold standard method in diagnosing bacterial meningitis. Factors such as turnaround time and decreased sensitivity of the culture after receiving antibiotics make molecular-based detection assay more in favor of being used and preventing the delay of starting appropriate management . NowadayWe report a prolonged positivity of GBS PCR from a 20-day-old neonate with GBS meningitis, despite receiving adequate antimicrobial therapy, normalization of CSF parameters, and negative CSF culture.A 20-day-old full-term girl was born to a primigravida mother by spontaneous vaginal delivery. The pregnancy was remarkable for a symptomatic urinary tract infection in the third trimester, in which she received antibiotics. Neither urine culture nor vaginal swab was taken.The patient was doing well until day 18 of life when the mother noticed poor feeding and excessive crying. Her clinical condition worsened over 48 h, and she started to have bluish discoloration of both lips with breath cessation and episodes of tonic upper and lower limb posturing lasting for a few seconds.Upon arrival at the Emergency Department (ED), she was lethargic, hypoxic, hypotensive, and tachycardiac. Her weight, height, and head circumference were all at the 50th percentile. Neurological examination was remarkable for Pediatric Glasgow Coma Scale (pGCS) 3 out of 15, pupils were equal and reactive. She was hypotonic with a bulging anterior fontanel. The remainder of the physical examination was unremarkable.Initial resuscitation measures were done and started on empirical antibiotics ampicillin and cefotaxime. Computed tomography (CT) scan showed moderate hydrocephalus with periventricular white matter edema and encystment of the fourth ventricle. An emergency external ventricular device (EVD) was placed.9/L (4.5–13.5 × 109/L), with 39% neutrophils and 41% lymphocytes. CSF analysis was suggestive of bacterial etiology, WBC of 107 × 106/L (0–5 × 106/L), RBC of 7 × 106/L (0–10 × 106/L), neutrophils 88%, lymphocytes 7%, protein of 4.16 g/L (0.15–0.40 g/L), and glucose of <0.06 mmol/L (3.30–4.50 mmol/L).Initial workup, including complete blood count (CBC) showed WBC of 10 × 10S. agalactiae . After 24 h, GBS was confirmed by CSF culture. Her antibiotic coverage was modified to ampicillin (400 mg/kg/day) and gentamicin (7.5 mg/kg/day) after the organism identification and sensitivity results. After 48 h, a repeated CSF sample showed sterilized culture; hence, gentamicin was discontinued. Further evaluation by magnetic resonance imaging (MRI) revealed ventricular dilatation and ventriculitis.CSF Gram stain showed Gram-positive cocci in chains. A few hours later, CSF FilmArray multiplex PCR came positive for Around 3 weeks of therapy, she started to have signs of high intracranial pressure, an increase in head circumference with worsening CSF parameters, including pleocytosis, low glucose, and high protein. CSF culture from EVD was negative; however, the PCR was still positive for GBS. Brain MRI showed worsening of ventriculitis with multi-intraventricular septated abscesses. Therefore, 10 days of intraventricular vancomycin (5 mg/day) was added to her current regimen (ampicillin) with improvement in CSF pleocytosis and resolution of increased intracranial pressure signs.At the near end of therapy (day 80), CSF PCR from the ventriculoperitoneal (VP) shunt was still positive for GBS. The patient continued on ampicillin for a total of 100 days until complete radiological resolution of abscesses and ventriculitis along with normalization of CSF parameters. The first negative CSF PCR for GBS was documented on day 225 (125 days from completion of therapy). The test was done to evaluate an acute deterioration that was found to be related to shunt malfunction. The patient did well with no recurrence of infection during 6 months of subsequent follow-up visits.Group B Streptococcus (GBS) is considered a predominant cause of bacterial meningitis in neonates, with a high morbidity and mortality rate  culture is the gold standard in diagnosing meningitis and isolating bacterial colonies for antimicrobial susceptibility testing. The sensitivity of CSF culture ranges between 70 and 90% –13. HoweA variety of diagnostic tests have had been introduced into clinical practice to overcome the abovementioned culture and Gram stain limitations. Latex agglutination test (LA) and immunochromatographic test (CIE) are the classical antigen detection methods commonly used in bacterial meningitis. They are considered to be rapid tests with direct testing of bacterial soluble antigens in the body fluids. Although prior antibiotics will affect the sensitivity of these tests, the duration of positivity is highly dependent on bacterial load , 22. In Lately, PCR became a fundamental diagnostic modality in culture-negative meningitis in many laboratory services. It can detect as few as 10–100 cfu/ml of bacteria in the CSF . FilmArrStreptococcus pneumoniae, 72−92% for Haemophilus influenzae, and 88–94% for Neisseria meningitides (S. agalactiae using ME PCR panel was found to be near 100% (The reported sensitivity and specificity of this method were exceeding 90%, compared with other tests , 31. Howear 100% , 33. Thiear 100% –37.S. pneumoniae and S. agalactiae, 17.5 and 15.4%, respectively. These results were based on a positive ME panel compared with other standard investigational methods and clinical condition of the patients (A recently published systematic review reported 4% false-positive results of the ME panel, with the highest rate observed in patients . In our S. pneumoniae in meningitis cases by PCR after 20 days of starting therapy (The duration of PCR positivity had not been well-studied after antibiotic administration. Hence, there was no clear explanation of the varieties of ranges in positivity. Brink et al. reported that 89% of patients with bacterial meningitis would have positive CSF PCR on days 1–3 of treatment, 70% on days 4–6, and 33% positive on days 7–10; however, the type of organisms was not mentioned . ConversOur case had a prolonged positivity of CSF PCR, and it continued to be positive during almost the entire course of therapy. The precise time of negativity in our patient is unknown as the VP shunt had been placed to manage her hydrocephalus, and no further CSF samples had been obtained afterward. The first documented negative PCR was after 4 months of completion of therapy when she was evaluated for possible infection vs. malfunction . There wThe significance of prolonged PCR positivity in the CSF is still yet to be determined, and more research is needed to evaluate the clinical utility of using PCR to ensure the complete resolution of infection. Culture and CSF parameters along with clinical condition should be the guidance to assess proper response to therapy.The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.NA and YF wrote the first draft. FA and MA wrote the final draft and edited the subsequent versions. All authors have read and approved the final draft of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


A fundamental part of the adolescent self is formed through interaction with intimates, usually family members whose roles are reasonably well-defined. However, donor siblings—children who share a sperm donor—lack social scripts for interacting with one another, particularly when they are raised in different households. Moreover, they are often challenged to figure out their relationship to newly discovered genetic relatives. This article examines how donor-conceived teens and young adults navigate relationships with their half siblings and form intimate relationships. Drawing on Garfinkel’s concept of indexing, or the use of familiar categories to make sense of new situations, these youth rely upon their personal knowledge of friends and family to figure out what kinds of relationship they can develop with donor siblings. Based on interviews with 62 youth aged 14–28, who had their own social media accounts and who had chosen to establish contact with their donor siblings, the articles discusses the three stages most donor siblings go through—“anticipation”, “first contact”, and “relationship building”—and the way those stages shape individual identity formation. In the course of the analysis, the article also explores whether interaction with donor siblings affected individual’s sense of identity and whether feelings of closeness with donor siblings differ for youth raised as solo children versus those who have siblings with whom they share a household. For those who report feeling close, youth describe how intimacy is sustained and negotiated at a distance. Finally, as much as youth pick and choose intimates from their larger network, the article also argues that their collective identity as related-kin members remains. Children conceived from donor gametes are born into nuclear families, but they are also born into an invisible  group of half-siblings who share half their genetic traits and also share deep questions about the roots of their own identity. Scholars of new kinship studies have been particularly focused on the ways in which new reproductive technologies ground families in bio-genetic connections while also presuming that these connections could constitute family ties. These scholars have shown how the cultural narrative around nuclear families has been stretched to accommodate children conceived through new reproductive technologies . Still to be explored, however, are important questions about donor siblings, family ties, and individual identity. For example, while donor-conception anchors their identity in a genetic grounding of kinship, donor-conceived individuals must contend with the fact that part of their identity comes from an anonymous person whose identity is protected and who they may never be able meet.  Children may reside in a nuclear family, but how does an anonymous genetic donor figure into a child’s search for identity from their genetic half-siblings? Moreover, the discovery of donor siblings could offer insight into shared, genetically rooted traits, but donor siblings have no claim to kinship. How do donor siblings fit into the cultural narrative of the nuclear family? Equally interesting, how might children raised with siblings in their nuclear families feel about becoming close to their donor siblings in comparison to those who are raised as solo (“only”) children? Contrasting the experiences of donor-conceived youth that have grown up in different social environments may help us unravel the differences between social and biological components of kinship.Voluntary registries, ancestry searches, and more openness have also increased awareness of the possibility of locating half-siblings and forming relationships between donor-conceived offspring. Social media has dramatically enhanced the ability of individuals who share the same sperm donor to find one another online . At the In her theorizing about the role of in vitro fertilization in redefining life, technology, and biology, Sarah Franklin  (p. 34) Encounters with genetic relatives carry significant implications for identity and self-concept among children, as well as for the meaning of kinship more generally. A fundamental part of the adolescent self is formed through interaction with intimates  whose roles are reasonably well-defined ,19,20. HTo date, research on donor-linked children and families has not provided answers to those questions. In particular, donor-conceived youth have rarely been asked their views on the implications of their newly found relatedness . This article uses interviews with donor-linked teens and young adults to explore how they navigate relationships with their half siblings and how they situate siblinghood within the context of other relationships, real or imagined, that already exist in their lives. Social and cultural contexts are important for two reasons. First, conventional notions of brothers and sisters shape children’s expectations about what relationships with donor siblings could or ought to be. Second, persistent differences between what those conventions proscribe and what youth experience could prompt the creation of new understandings.Donor-conceived individuals reside in a context bordered by convention and novelty. On one side, labels such as brother, sister, or cousin imply a great deal about such things as familiarity, intimacy, and reciprocal obligations.  had located their half-siblings through donor sibling registries. Participants were interviewed in parts of the U.S. associated historically with the rise of the fertility industry as big business. We traveled to six major metropolitan areas within the U.S. to conduct in-person interviews. Parents and their donor-conceived children were interviewed separately, usually simultaneously. This allowed each person to tell their own account of events and relationships. The majority of interviews were conducted in-person. When it was not possible to meet face-to-face, interviews were conducted over Skype.  Interviewing in person or virtually produced the same quality of data [Semi-structured questions with probes were developed and parents and children were asked similar questions  and then more specific codes . Construction of the codes was guided by the principles of grounded theory, with emerging themes identified and then reanalyzed for consistency and completeness ,30. The analysis presented in this paper is based upon a subset of interviews with 62 youth aged 14–28 (median age 17.5), who had their own social media accounts and who had chosen to establish and maintain contact with their donor siblings. Among the respondents 36 were girls (median age 17) and 26 were boys (median age 18). The majority of youth were white, identified as heterosexual, and thought their families were middle class. At the time of these interviews, 17 youth had contact with their donors and 45 youth did not. Those who had made contact usually had identity release donors. Members within each donor network lived throughout the U.S. and some lived abroad, making it difficult to meet regularly in person. Parents of these youth provided information about their household incomes, and 43% earned below USD 100,000. Youth often noted that they would have liked to meet more frequently with their donor siblings, but family resources did not always permit this.In 2021, these 62 interviews were recoded by myself and a research assistant to ensure intercoder reliability. The new coding scheme examined how they viewed their donor siblings along several dimensions: in comparison to siblings in their household; in comparison to friends from school or camp; in terms of how they were described to others ; feeling of intimacy or distance; and the content of their communication. The tables presented in this article were constructed based upon recoding of the initial interviews.Ten follow-up interviews with current college-age youth were conducted in 2020–2021 in order to learn about changes in their donor sibling relationships, about how these relationships continued without their parent’s supervision and whether feelings of closeness change when additional donor siblings join. On Zoom, individual interviews were conducted with four youth who have siblings in their households and four youth who do not have household siblings. These interviews were meant to flesh out siblinghood understandings and to confirm my recoding process. Finally, a pair of donor siblings from a large network that I have been following were interviewed together, and they provide a current look at the continued functioning of the broader network. Lack of funding limited my ability to continue to gather additional updates. I indicate throughout when I am referring to a follow-up interview.This article draws upon original data that were not analyzed prior to comparing youth with household and non-household siblings. Moreover, the themes developed in this article resulted from recoding this subset of interviews.Since parents in all family types were enthusiastic about facilitating contact with their child’s half siblings, these youth felt comfortable about how these donor siblings could become meaningful in their lives. Therefore, I wanted to understand how donor-conceived youth incorporate these genetic relatives into their lives; how donor siblings might be important to their identity; and whether these connections were like siblings raised together.When asked to recall their initial reaction to learning that there were kids “out there” with whom they shared a sperm donor, our interviewees expressed a wide array of emotions: surprise, confusion, and curiosity were among the most frequently mentioned. Oliver recalled asking: “just because they have the same genetics, does that mean they’re my family?” The fact of shared genes amplified interest in knowing more about peers who were otherwise strangers. Andy, a high school senior, described the sensation this way: “the fact that we share such similar blood is … a catalyst for getting to know each other”. He recalled trying to puzzle through the situation as an 8-year-old: “the toughest part was when I don’t know what questions to ask. Like you don’t know how touchy you can be on a certain subject, how OK certain things are. Because these are your family, and if they were your normal siblings that you grew up with, this would be stuff you already shared. Stuff like political orientation or socioeconomic status”. Even those who ultimately chose not to make contact grappled early on to put a label on their donor siblings.Unprecedented relationships are often socially scripted the first time using conventional ideas and experiences. Garfinkel  referredDonor siblings can also be a curiosity because they offer unique benefits. For example, Nelson et al.  (p. 32) In other words, they are imagined as “fun”, “cool”, and “neat”, and people who might immediately understand them. Equally important, half-siblings might give them insight into their genetic origins  at a moment in time when they are engaged in their own search for identity.An important and recurrent theme in interviews with the youth who chose to get to know their donor siblings was their openness to new and potentially intimate relationships. No one foresaw their encounters as likely to displace or diminish the intimate relationships already in their lives. In making this point, I draw upon Jamieson’s  (p. 1) dThe reanalysis of these interviews for this article revealed that donor sibling interaction occurred in three distinct stages: anticipation, first contact, and relationship building. During these stages, kids experimented with using what was known and familiar to them in friendships and families to incorporate new people in their lives. Based upon the evolution of these interactions, indexing either “succeeded” by reaffirming conventional labels of friend or family or it “failed” in that it led them to create categories that were not strictly one or the other.Prior to first contact, children (and often parents) tried to figure out what they wanted to accomplish from meeting. Youth had widely divergent expectations. For example, Gabriella, who had no siblings within her immediate family, hoped “that I would find maybe like a true brother or sister—like where you’re really close with them”. Diane, a 17 year-old high school student who still lived at home with a brother, put it this way: “I wanted an older sister who would lend me her clothes or give me her makeup. Something like you read about in the books. I wanted something a little more stereotypical in my life”. Ethan, who had two sisters, recalled hoping he would find a brother when he heard that his mom had planned a first meeting with his donor siblings: “maybe the guys in my donor-group would have something to talk about because I didn’t really have a whole lot of intimate guy friends and I wanted a brother. So I thought that might be cool”. By contrast, Marc who already had a brother and a step-sister “thought that donor siblings would be like a fun new friend group” but added that “I don’t really need more family than I already have”.In anticipation of first contact, most of the youth recalled using definitions of friend versus family to set boundaries on their obligations and commitment to their donor siblings. Those who used the language of family anticipated more serious, intimate relationships to develop; friendship, on the other hand, connoted distance, allowing for fun and perhaps intimacy without the intensity or reciprocity that familial relationships imply. Later, in this article, I discuss the relationship between household composition, gender, and feelings of intimacy.Imagined relationships were challenged as youth first encountered the real people attached to their fantasies. Instead of using friendship and family as abstractions through which to assign types of obligation, they compared these new emotional connections to ones they felt for “real” friends and family.As they interacted for the first time, many of the youth began experimenting with a siblinghood narrative grounded in similarities and differences, especially around physical resemblance and personality traits, much as non-donor-conceived children who grew up in the same household . As thesThe fact of physical resemblance encouraged Sally and others to reflect on the multiple bases of kinship in their lives. Sally explained: “I grew up with just my mother. I had one cousin that I was close to. I never really had much of a family except my mom’s sorority sisters (and they) have completely absorbed us into their family. I have 30 people that I call cousins, aunts, and uncles that I’m very close to and love and see often.”The idea that kin could be chosen—not just given or imposed—made it possible to see donor siblings as potential kin without necessarily displacing household siblings raised together.First contact also gave children the opportunity to use play to “try out” group and kinship definitions. For instance, at the first meeting of nine donor siblings ranging in age from 10–15, the older kids reported feeling protective and watchful of the younger ones as they scurried around late at night at the hotel where they were staying. Even though their ages were relatively close, they squeezed themselves into a hierarchy based on age differences. New joiners to the group embraced this hierarchy as a central feature of their relatedness. Similarly, Hertz and Nelson   first connection, relationships can develop into something that resembles a social script about friendship or even shared family membership.When indexing does not work—when, for example, the category does not do justice to the experience—new categories may come into being. However, new categories rarely survive without repetition; repetition requires dedicated effort, creativity and even courage. As I will show in the next section, developing a relationship with genetically related strangers involves bridging categories that are familiar but not always compatible.Youth who were raised with siblings and who had already developed strong understandings of siblinghood tended to set a high bar for their new genetic relatives. Almost three-quarters (71.4%) considered only those siblings in their household as immediate family see . Alice, By contrast, youth raised as solo or only children were more likely to consider themselves close to one or more donor siblings . That did not mean that siblinghood came naturally. For example, Amy said: “I don’t even have a lot of boy cousins and I obviously don’t have any siblings so I never had a brother relationship besides my really good guy friends. So it was really hard to try and establish that brother-sister relationship”. Max recalled vividly being thrust into the role of “older brother” when he met the first of his many donor siblings, “Harper hates pigeons. It’s awful, to the point in which the first time we saw pigeons, which are everywhere in New York, and I mean everywhere, he came and hid behind me and was terrified. I’m all like, what is happening? I’m really confused about this but I learned that this person, who had just met me, was already seeking security from me”. Feeling brotherly or sisterly sometimes required a presentation of oneself that allowed for differences, such as annoying quirks or just not sharing the same viewpoints. For example, Sam was raised as an only child, and in his first year of college he talked about the distinctive qualities of his relationship with his donor sibling: “We do have a brother-sister relationship. I think you have to have that certain feeling of familiarity and closeness to be able to argue about certain things or to share our different opinions about things. Sometimes when I tell people my sister is such a sorority girl I think the way I say it is more loving at the same time, just in that brotherly, like, ‘Oh man, my sister. I don’t know what she’s doing’”.In other words, solo children such as Amy, Max, and Sam found themselves “doing” siblinghood without any preparation. They had to figure out a social script that they had not grown up with as a natural part of their everyday family life.become family” (emphasis added)—similar to his “closest best friends” who were “random people I basically met and they became close enough to me that they crossed that same bridge”. The notion of a bridge is important because he felt obligated to the two high school friends he had selected to “crossover” from friends to family. He characterized this as a conscious process: “I had months of kind of being able to let myself say, ‘Listen, you need to be able to dismiss this idea of what is traditionally family’”. Donor siblings would never cross this bridge if these interviewees weren’t looking for (or weren’t prepared for) intimacy.The most interesting instances involved children who found themselves in a hybrid territory where donor siblings were neither “just friends” nor “immediate family”. Oliver explained that he liked all five kids he met but he considered only two to be family. Those two kids were not family because they shared the same donor but because they had “There were no significant gender-based differences in feelings of intimacy with donor siblings. In Whether their encounters were casual or intense, these young people came to recognize that maintaining a relationship took real effort and dedication. Absent physical proximity in a household or a shared neighborhood and school, their paths did not cross frequently. In order to move from shared genes as a curiosity to friendship or something approximating feeling brotherly/sisterly kids had to work on siblinghood at a distance.Interviews with these respondents revealed that donor offspring leveraged technology in their pursuit of siblinghood. The salience of technology lies in the choice it provides participants as to how open and frequent communication would be ,35. IntiYouth employed apps such as Instagram and Snapchat to initiate and sustain trusting relationships even in the absence of calling or meeting physically. This research extends Andreassen’s  (p. 367)In Girls were more likely to maintain relationships through social media than boys see . We don’However, it is important to note that Ethan’s twin sister did maintain contact with both their favored donor sibling and their moms. Ethan said that he relied on his twin to be in communication and to pass along information.I looked at whether length of time knowing donor siblings mattered to feeling close (data not shown) and found that the time-based determination of how close a respondent felt to a donor sibling hinged on knowing them for at least a year. In a follow up interview Julia, now age 21, talked about a new donor sibling. They remained in the early stages of trying to get to know each other. Looking at her Instagram profile, Julia “got a good idea of who she was and then I chose a topic to talk to her about”. Early on they identified a shared interest in a band and were able to “start a conversation based on that”. Even though they texted frequently, Julia’s emotional bond remained underdeveloped as compared to her longer-term relationship with her closest donor sibling. For now, they lean into the shared topic but have not established the complexities of sharing other intimate life details, nor have they met in person.Finally, technology allowed young people to set clear and explicit boundaries to their relationships. For example, it made it possible to learn about new donor siblings as soon as they appeared. It offered people greater latitude in how they structured their communication, what they wanted to get out of it, and when they wanted to partake. While I have no evidence that technology accelerates the development of emotional bonds, it did allow people to do the work of siblinghood over long distances.The opportunities for bonding were not as great in “mature” networks (defined as those over five years old), particularly when those who joined early felt closer to the original core members . Sally However, many networks remained meaningful precisely because members shared a donor whose identity was at least indirectly linked to their own. Even if they scoffed at the idea that genes determined identity, most members were at least curious to learn more about the donor . In instances where donors had not agreed to reveal themselves, network members had to figure out whether to search  and how broadly to share the information they uncovered. In the case of identity-release donors, when the oldest child turned age 18 they were often expected to post the letter they received from their shared donor to the network’s Facebook page. This gave donor siblings more information and some assurance that if they wrote to their donor they would write back or meet with them. This sense of obligation to the network reinforced a collective identity.A useful example of how this operated came from interviews with 16 members of a network that identified itself as the “7008ers”   attached to their experiences. This approach has given us the opportunity to consider siblinghood as both a status and a process. The net benefit has been a rare opportunity to see a meaningful new social category unfold.Three key findings deserve further consideration—for both future research and policy. First, donor siblings provide youth a resource for exploring the foundations of personal identity, i.e., the traits they share with others  and the ones that are unique to the individual and their immediate context. They help youth develop a deeper understanding of what it means to be donor-conceived and to have an anonymous donor at a time when friends need to be educated, too, regardless of whether they can eventually meet him or receive more information about him. (Future research might want to explore how siblings raised together come to agree that they favored certain donor siblings within their network). Among these youth family type, geographic region or social class were not likely to factor into their decisions. However, though their involvement with donor siblings they did learn about families that were different than their own adding to their understanding of diversity (such as seeing a loving relationship between a same-sex couple that they did not experience in their single mom household.) While it is too soon to say whether interactions with donor siblings have an enduring impact on identity, it is nonetheless important to note that by the time they were interviewed most respondents had been in touch with their donor sibling network for several years.Second, the feeling of belonging to a network of donor siblings  turns out to be important even when membership is a weak tie. That is, membership in the network may be deemed purely instrumental , but it is a membership nonetheless and a unique one by contrast to conventional kin ties. As we saw in a number of instances, membership in a network can be a doorway to deeper and more intimate social ties that supplement existing ones or that establish entirely new ones. Feelings of intimacy—whether based on blood, genes, or age—turn out to be far more real and durable than prior research had found. However, these youth did distinguish between obligations based upon relatedness to the entire network versus a smaller group with whom they formed more intimate ties.Third, siblinghood takes work among youth who share a donor—a form of emotional labor largely taken for granted among siblings who share a common household. This is not to say that parents do not shape relations between siblings in a conventional household; it is to say that the benefits of having donor siblings cannot be taken for granted. They have to be intentionally established and sustained—in a fashion that siblings raised together discover only when they leave the household. These youth deploy ideas and concepts from familiar cultural tropes about people who are their friends or family to figure out how to situate their new half-siblings. Since these networks can grow quite large, youth do choose with whom they want to establish more intimate ties.Future research would benefit from a longitudinal view of many of the findings and underlying processes described in this article. For example, it is not clear whether new members will find donor sibling networks as open to the formation of intimate ties as the originators did. In addition, on the policy side, the formal and legal status of donor-sibling ties remain unclear . Donors


Lumbar spinal stenosis (LSS) is a common neurodegenerative condition. However, how neurogenic claudication develops with severe leg pain has not yet been clearly elucidated. Moreover, cerebrospinal fluid (CSF) physiology at the lumbosacral level is poorly understood because of the difficulties involved in quantification and visualization. Recent studies have suggested that assessment of mitochondrial function in CSF provides an indirect way to assess neurological disorders and an important feature of disease progression. In this study, we assessed the relevance of endogenous extracellular mitochondria in the CSF of rats after LSS. Mitochondrial changes within the CSF were analyzed following LSS at 1 week using flow cytometry. An increase in cell size and number was observed in CSF with LSS, and reactive oxygen species (ROS) levels were also increased within the CSF at 1 week in the LSS group. Elevated mitochondrial ROS and functional changes in the CSF are hallmarks of LSS. The present study is the first to demonstrate that elevated mitochondrial ROS within the CSF is a new index for the early detection of LSS. Moreover, it may represent a potential novel treatment target for LSS. Cerebrospinal fluid (CSF) can be used for the early diagnosis of changed pathophysiological states of various conditions and as a therapeutic indicator . Existin3) was implanted at the L4 level using no. 5 fine forceps. Sham-operated rats underwent laminectomy at the L5 level, without implants. The spinal cord was then covered with Surgicel® absorbable hemostat . To prevent infection, all rats were injected intramuscularly with 40 mg/kg cefazolin sodium  after suturing. All rats were also administered an oral dose of 10 mg/kg Children’s Tylenol®  after anesthesia was resolved for pain management. Rats  were sacrificed 1 week after silicone implantation.Male Sprague–Dawley rats  were obtained from Daehan Bio Link . All procedures were approved by the Jaseng Animal Care and Use Committee . Rats were housed in standard cages under constant temperature (23–25 °C) and humidity (45–50%) with a 12 h light/dark cycle. The rats had free access to food and water. Animals were anesthetized with 2–3% isoflurane gas , and a dorsal laminectomy was performed at L5 using fine rongeurs. Next, a silicone block  scale, and the horizontal ladder test as described previously . The BBBThe CSF was prepared in accordance with previously published protocols  and collA flow cytometric assay was used to investigate altered reactive oxygen species levels and endogenous extracellular mitochondrial changes within the CSF after LSS. The collected CSF should be analyzed immediately for flow cytometric analysis and kept in 37 °C on heating block  during the time between sampling and analysis. Briefly, the collected 200 µL of CSF was centrifuged at 2000 rpm for 3 min. The supernatant was carefully removed using a pipette and collected in another tube. The cell pellet was resuspended in different staining solutions. The following four staining solutions were prepared as follows:(A) Cellular ROS level detection solution: cellular ROS levels were measured in CSF using 2′,7′-dichlorofluorescin diacetate . We prepared a 5 mM stock solution by dissolving 9.3 mg DCFDA powder in high-quality 3.8 mL anhydrous dimethylsulfoxide (DMSO) solution and prepared 1 mL of 10 µM DCFDA solution.(B) MitoSOX solution: we prepared a 5 mM MitoSOX  stock solution by dissolving 50 µg of MitoSOX in 13 µL DMSO solution and prepared 5 µM MitoSOX working solution with 1 mL of a BSA stain buffer  for staining.(C) Mitotracker solution: we prepared a 1 mM Mitotracker  stock solution in DMSO solution, and prepared 200 nM Mitotracker working solution with 1 mL of a BSA stain buffer. (D) TMRM solution: we prepared a 10 mM Tetramethylrhodamine, methyl ester  solution by dissolving 25 mg of TMRM in 5 mL DMSO solution and prepared 10 nM TMRM working solution with 1 mL of a BSA stain buffer.The staining solution (0.1 mL) was directly added to the cell pellet and immediately analyzed using flow cytometry . The mean positive cell values, as determined via flow cytometry, were expressed as a percentage relative to the sham group.Total DNA was extracted from 200 µL of CSF according to phenol-chloroform-thiocyanate guanidine , as described in detail previously . A 200 µThe mitochondrial DNA (mtDNA) concentration was analyzed quantitatively between a target mitochondrial gene and a reference nuclear gene (mtDNA/nDNA) using quantitative real-time PCR (qPCR), as described previously. Briefly, mtDNA/nDNA ratios were measured by quantifying the number of mtDNA molecules per nDNA molecule calculated by the classical ΔΔCt method used for qPCR analysis using the following primers: mitochondrial NADH-ubiquinone oxidoreductase chain 1 (mt-ND1) forward: 5′-CCGTCCTCCTAATAAGCGGC-3′ and mt-ND1 reverse: 5′-TATGGCTATTGGTCAGGCGG-3′; GADPH forward: 5′-CCCCCAATGTATCCGTTGTG-3′ and GAPDH reverse: 5′-TAGCCCAGGATGCCCTTTAGT-3′.p < 0.05 or ** p < 0.01 vs. the sham group and were analyzed via unpaired t-test with Welch’s correction.All numerical data are expressed as mean ± standard deviation. Prism 9.0  was used for all analyses. Data are expressed as the mean ± SEM. Significant differences are indicated as * The inset of the surgical images illustrates the procedures performed. The first image from the left shows that the laminectomy was performed in the L5 vertebral lesion without nerve compression to push the silicone block into the L4 level A. A siliTo assess the changes in cell size and number within the CSF after LSS, we analyzed CSF collected from the sham and LSS models at 1 week by flow cytometry A. The quWe also examined changes in endogeneous extracellular mitochondrial mass within the CSF after LSS. To verify the mitochondrial mass within the CSF, MitoTracker red fluorescent dye (MTR) has been commonly used as a powerful tool to evaluate the mitochondrial mass within CSF using flow cytometry A. MTR po2DCFDA (DCFDA) to confirm cellular ROS levels within the CSF using flow cytometry (2−) in the mitochondria. Previous studies have demonstrated that mitochondrial changes are closely associated with neurological diseases and were recently discovered within the CSF. We analyzed whether mitochondrial oxidation in CSF was elevated after LSS by flow cytometry, as shown in We investigated ROS production and mitochondrial ROS (mtROS) changes within the CSF 1 week after LSS. ROS have long been known to cause oxidative modifications to changes in some cellular components. Mitochondria are the main sources of ROS within mammalion cells. Overproduction of ROS causes oxidative damage to lipids, proteins, and DNA, which has been implicated in various diseases in response to oxidative stress, including cancer and respiratory, cardiovascular, neurodegenerative, and digestive diseases. Thus, ROS quantification in the CSF has long been considered suitable for the diagnosis of various diseases. We detected oxidized CM-Hytometry A. DCFDA ytometry B. In addytometry C. MitoSONext, we also confirmed whether the change in MMP in mitochondria in the CSF was causally related to LSS. TMRM is a cell-permeant dye that accumulates in active mitochondria with intact membrane potentials. Flow cytometric analysis of the CSF was performed to detect changes in TMRM 1 week after LSS A. TMRM pOxidative stress has been proposed as an important pathophysiological mechanism in cardiovascular and degenerative diseases, as well as in neurological diseases, and excessive ROS production has emerged as the main cause . MitochoAging is the result of an accumulation of oxidative aged population when cell homeostasis is not maintained. The accumulation of this oxidative damage to intracellular proteins and organelles is normally repaired by the homeostatic system, but when the function of this system is reduced with age, ROS production in aged mitochondria causes oxidative damage to organelles and macromolecules as by-products of numerous enzymatic reactions and consequently creates an oxidative stress environment that triggers cell death and tissue damage ,23. TherThese preliminary findings suggest that altered levels of ROS, mtROS, and MMP in CSF are pathophysiologic phenomena for understanding and treating LSS and are potential biomarkers for the diagnosis of LSS. However, we do not know CSF pathophysiological changes in the chronic stages of LSS. Additionally, there have been few studies on the relationship between the increase in mitochondrial oxidative stress in the CSF and neuronal injury, pain, and behavioral changes with LSS. Based on this study, with further research on the relationship between the quantitative and qualitative changes of mitochondria in CSF, pathophysiological mechanisms, and functional changes occurring after a given LSS, the mitochondria in CSF are expected to be useful indicators for the early diagnosis and development of treatment methods for LSS.In this study, we found that ROS and mtROS production was increased in the CSF of LSS rats, and MMP was also decreased in CSF after LSS. We concluded that endogenous extracellular mitochondrial changes in the CSF might contribute to LSS-induced pathophysiological processes. Therefore, assessment of mitochondrial changes in the CSF may indirectly provide a way to diagnose LSS, adding a promising and complementary strategy to the treatments of LSS.