Patients with neurofibromatosis type 2 (NF2) develop bilateral cochleovestibular schwannomas (CVSs) that cause binaural deafness in most individuals. Hearing loss occurs in an unpredictable manner and the underlying mechanisms are not known. To gain insight into the pathophysiologic basis for hearing loss in NF2, we performed a prospective cross-sectional study of untreated ears in NF2 patients.One hundred consecutive NF2 patients in a prospective natural history study were included. Clinical and audiometric data were analyzed for treatment naïve ears. In addition to standard MR-imaging sequences, alterations in intralabyrinthine protein content were determined utilizing high resolution FLAIR, the presence of cochlear aperture obstruction was determined by examining 3D T2 sequences, and endolymphatic hydrops was identified on delayed post-contrast FLAIR sequences.3, including 14 ears (88%) with block of the cochlear aperture and elevated protein.Eighty-nine ears harboring 84 untreated CVSs in 56 consecutive NF2 patients (age 30±16 years) were analyzed. Thirty-four (38%) ears had varying degrees of hearing loss. Elevated intralabyrinthine protein was identified in 70 (75%) ears by FLAIR MR-imaging and was strongly associated with the presence of hearing loss . Elevated intralabyrinthine protein was associated with the presence of CVS-associated cochlear aperture obstruction  in both normal and hearing loss ears. Elevated intralabyrinthine protein was not identified in ears without CVS (5 ears). While larger tumor size was associated with hearing loss (P = 0.006), 16 hearing loss ears (47%) harbored CVSs less than 0.5 cmThese findings are consistent with a model in which hearing loss develops as a result of cochlear aperture obstruction and accumulation of intralabyrinthine protein. MRI based identification of elevated intralabyrinthine protein may help identify the ear at-risk for developing hearing loss. NF2 tumor suppressor gene located on the long arm of chromosome 22 Neurofibromatosis type 2 (NF2) is an autosomal dominant heritable neoplasia syndrome. It results from a germline mutation of the Despite the significant audiologic morbidity identified in patients with NF2, the mechanisms by which the CVS causes hearing loss are not understood. The most frequently cited hypothesis is the enlarging CVS causes hearing loss through direct compression and stretching of the cochlear nerve. Several phenomena, including the unpredictable onset of hearing loss, frequent association of hearing loss with small tumors and progressive hearing loss in patients with non-growing CVS specifically suggest that such a simple association between tumor size and/or growth rate with hearing loss does not exist Patients enrolled in a National Institute of Neurological Disorders and Stroke (NINDS) institutional review board (IRB)-approved prospective NF2 natural history study (NIH#08-N-0044) were included. Informed written consent was obtained from all adult participants. Informed written consent from the next of kin, carers or guardians on behalf of minors participating in this study was obtained. Both written consent and assent forms were approved for the consenting procedure by the NINDS IRB. Treatment naïve ears with no evidence of conductive hearing loss were used for analysis. Patients had NF2 diagnosed by clinical and/or genetic criteria Detailed histories were obtained and comprehensive otologic and neurologic examinations were conducted in all patients to exclude the presence of middle ear disease. Concurrent audiometric evaluations were performed that included air- and bone- conduction thresholds from 250–8000 Hz and 250–4000 Hz, respectively. Hearing was stratified utilizing the four frequency pure-tone average (PTA) as normal [PTA≤20 dB], mild hearing loss [PTA 21–40 dB], moderate [PTA 41–70 dB], severe [PTA 71–95 dB], or profound [PTA>95 dB] Patients underwent magnetic resonance (MR)-imaging with and without contrast (T1 weighted) of the craniospinal axis. A neuroradiologist, blind to the hearing status of individual patients and ears, interpreted all imaging findings. Inner ear MR-imaging was performed with less than 1 mm in plane resolution utilizing a 3T-MR-scanner . Non-contrast enhanced fluid attenuated inversion recovery (FLAIR) sequences were performed to assess for the presence of elevated protein within the inner ear. Because saline-based solutions become hyperintense relative to brain parenchyma at defined protein concentration thresholds, identification of elevated intralabyrinthine protein by pre-contrast FLAIR MR-imaging is dependable and was reported as either being “elevated” or “normal” Volume of the CVS was determined utilizing post-contrast T1-weighted images Statistical analyses were performed as defined in text. A P-value less than or equal to 0.05 was considered significant.Of 100 consecutive patients (200 ears) enrolled into the NF2 natural history study, ears that underwent surgery (84 ears in 58 patients) and/or received radiation therapy (26 ears in 20 patients) for management of cochleovestibular schwannomas were excluded from this study. Additionally, 5 patients (10 ears) receiving chemotherapeutics at the time of this study and 1 patient (2 ears) unable to complete audiometric examination (English second language) were also excluded from evaluation. Three ears with mild hearing loss were also excluded from analysis due to the presence of a conductive hearing loss component by otologic and audiologic evaluation. Therefore, 89 treatment naïve ears  in 56 consecutive patients  were included. In 23 patients (41%), one ear met criteria for inclusion and in 33 patients (59%) both ears met inclusion criteria. MR-imaging evidence of CVS was present in 84 of the 89 ears; 5 ears had no MR-imaging evidence of CVS. Mean patient age at evaluation was 30±16 years . Forty-nine patients (88%) had audiovestibular symptoms associated with a CVS . Mean agFifty-five ears  had normal hearing (PTA≤20 dB), including 5 (6%) ears without a CVS. Thirty-four ears (38%) had associated hearing loss . Mean PTA was 54±29 dB  in the ears with associated hearing loss. Hearing loss occurred gradually over months to years , in a stepwise manner characterized by periodic decrements in hearing associated with intervening periods of stable hearing , in a relapsing-remitting pattern defined by periodic decrements in hearing coupled with partial recovery of hearing during intervening periods , or in a sudden and complete fashion  . Subjective hearing loss was not reported in 3 ears (9%) in 3 patients with audiometric evidence of mild hearing loss.3). Other imaging findings and audiovestibular symptoms in the 56 study patients (89 ears) are detailed in Radiographic and audiologic analysis in the 34 hearing loss ears revealed that 32 ears (94% of ears with hearing loss) had elevated intralabyrinthine protein on FLAIR MR-imaging . The 2 hCochlear aperture obstruction by a CVS was closely associated with identification of elevated intralabyrinthine protein in hearing loss ears . While 31 hearing loss ears (91%) with elevated protein in the labyrinth had cochlear aperture obstruction by a CVS, only 1 ear (3%) with elevated intralabyrinthine protein did not have evidence of cochlear aperture obstruction , 2. EarsTwenty-three ears  had isolated cochlear aperture obstruction and 8 (26%) had cochlear aperture obstruction associated with either a discrete intralabyrinthine tumor (3 ears)  or direcFifty normal hearing ears (91%) harbored a CVS and 5 ears (9%) did not have an associated CVS. Radiographic and audiologic analysis of the 50 normal hearing ears with a CVS demonstrated elevated intralabyrinthine protein in 35 ears  and normal intralabyrinthine protein in 15 ears (30%) on FLAIR MR-imaging. The 5 normal hearing ears without CVS did not have evidence of elevated intralabyrinthine protein .Similar to hearing loss ears, cochlear aperture obstruction by a CVS was associated with elevated intralabyrinthine protein in normal hearing ears . While 33 normal hearing ears  with elevated intralabyrinthine protein had cochlear aperture obstruction by a CVS, only 2 ears (6%) with elevated intralabyrinthine protein did not have evidence of cochlear aperture obstruction.Specific factors associated with elevated intralabyrinthine protein included isolated cochlear aperture obstruction by CVS , cochlear aperture obstruction with direct labyrinthine invasion by CVS , cochlear aperture obstruction with a discrete intralabyrinthine tumor  or unknown mechanism . Endolymphatic hydrops was also detected by MR-imaging in 3 normal hearing ears with elevated protein and block of the cochlear aperture.Twelve normal hearing ears harboring a CVS  without elevated intralabyrinthine protein did not have block of the cochlear aperture, including 1 ear (8%) with associated hydrops. Three normal hearing ears (20%) had evidence of cochlear aperture block by CVS without elevated protein.3 (approximately 1.5 cm in maximum linear dimension). While the presence of hearing loss was correlated with larger CVS volume in hearing loss ears , 16 (47%) hearing loss ears had a CVS that was less than approximately 0.5 cm3 .CVSs were identified in 84 ears (94%) and were purely intracanalicular in 38 ears (45%). Mean tumor volume (in 84 ears) was 1.8±4.0 cm 0.5 cm3 . Among 3Previous studies have demonstrated that CVS-associated binaural hearing loss will occur in an unpredictable manner over the lifetime of most NF2 patients The most common imaging findings identified in CVS-associated hearing loss in NF2 was the presence of elevated intralabyrinthine perilymphatic protein and the presence of cochlear aperture obstruction on MR-imaging. Elevated intralabyrinthine protein was found in 94% of hearing loss ears (32 of 34 ears) and in 70% of normal hearing ears (35 of 50 ears). Blockage of the cochlear aperture by an associated CVS was found in 96% of ears (64 of 67 ears) with elevated protein and only in 14% of ears (3 of 22 ears) without evidence of elevated intralabrynthine protein. These findings are consistent with the findings by Silverstein and colleagues The importance that elevated intralabyrinthine protein plays in hearing loss is underscored by previous clinical-imaging studies of the inner ear in other conditions, including sporadic vestibular schwannomas and sudden sensorineural hearing loss (SNHL) The findings of the current study indicate that cochlear aperture block underlies elevation of intralabyrinthine protein. The sensitivity and specificity of cochlear aperture obstruction in identifying elevated perilymphatic protein within the labyrinth was 96% and 87%, respectively. This indicates a pathophysiologic association between cochlear aperture obstruction and the presence of elevated intralabyrinthine protein may exist in NF2-associated CVSs. Based on the results from this study and previous studies examining elevated intralabyrinthine protein in other hearing loss syndromes, NF2-associated tumors may lead to elevated intralabyrinthine protein levels in several ways related to cochlear aperture obstruction that causes abnormal protein clearance and deposition.Elevated intralabyrinthine protein could be the result of cochlear aperture obstruction and disruption of the blood-CSF/labyrinthine barrier caused by permeable tumor vessels Another mechanism by which protein can accumulate within the perilymph associated with cochlear aperture obstruction involves impaired clearance caused by the CVS. It has been shown that the cochlear nerve is integral in the rapid transport of proteins from the cochlea to the cochlear nucleus Elevated intralabyrinthine protein could also be the result of increased protein production or deposition. Analogous to cerebellopontine angle CVSs that are known to cause increased protein content within the circulating cerebrospinal fluid compartment Elevated intralabyrinthine protein on MR-imaging was closely associated with the presence of hearing loss. The importance of elevated intralabyrinthine protein underlying hearing loss is supported by previous studies examining unique perilymphatic proteins that are elevated in CVSs, including μ-Crystallin (CRYM) and low density lipoprotein-related protein 2 (LRP2) A simple association between tumor size and hearing loss does not explain several phenomena. For instance, hearing loss in NF2 has an unpredictable onset and variable progression, which may be gradual, stepwise, relapsing and remitting, or sudden and complete. While previous studies have attempted to link increasing tumor size with hearing loss in patients with NF2, this association has not been established because of the ubiquitous presence of small tumors within all series that are associated with hearing loss. Because hearing loss in NF2 may be caused by end organ degeneration Other pathophysiologic processes of the inner ear structures have been implicated with hearing loss, including the development of endolymphatic hydrops and intralabyrinthine hemorrhage Bevacizumab, initially utilized in NF2 clinical trials for the treatment of growing vestibular schwannomas was associated with hearing improvement in a subset of patients  The appropriate stratification of benefit to risk ratio for hearing preservation attempts in NF2 requires delineation of at-risk ears for hearing loss. Because hearing loss is currently the most likely outcome in NF2 ears, it becomes imperative to avoid risk when hearing loss is unlikely to occur. Despite the variable presentation of hearing loss in NF2, most ears with normal perilymphatic protein signal had normal hearing  and most ears with hearing loss had elevated perilymphatic protein .Based on the available body of evidence and the current findings that indicate elevated perilymphatic proteins may underlie the final common pathway leading to hearing loss, MR-identification of labyrinthine hyperintensity in normal hearing ears (35 of 50 ears in this study) may serve as a potent imaging biomarker of ears at-risk for developing hearing loss.


Approximately 2–4% of newborns with perinatal risk factors present with hearing loss. Our aim was to analyze the effect of hearing aid use on auditory function evaluated based on otoacoustic emissions (OAEs), auditory brain responses (ABRs) and auditory steady state responses (ASSRs) in infants with perinatal brain injury and profound hearing loss.A prospective, longitudinal study of auditory function in infants with profound hearing loss. Right side hearing before and after hearing aid use was compared with left side hearing (not stimulated and used as control). All infants were subjected to OAE, ABR and ASSR evaluations before and after hearing aid use. The average ABR threshold decreased from 90.0 to 80.0 dB (p = 0.003) after six months of hearing aid use. In the left ear, which was used as a control, the ABR threshold decreased from 94.6 to 87.6 dB, which was not significant (p>0.05). In addition, the ASSR threshold in the 4000-Hz frequency decreased from 89 dB to 72 dB (p = 0.013) after six months of right ear hearing aid use; the other frequencies in the right ear and all frequencies in the left ear did not show significant differences in any of the measured parameters (p>0.05). OAEs were absent in the baseline test and showed no changes after hearing aid use in the right ear (p>0.05).This study provides evidence that early hearing aid use decreases the hearing threshold in ABR and ASSR assessments with no functional modifications in the auditory receptor, as evaluated by OAEs. Perinatal brain injury (PBI) consists of a large group of conditions that produce mild to severe impairments in motor, visual, auditory and cognitive functions Currently, the most useful techniques for early hearing loss detection are auditory brainstem responses (ABRs) and otoacoustic emissions (OAEs); however, new techniques such as auditory steady state responses (ASSRs) have been developed. These techniques show high sensitivity for detecting hearing loss in healthy and PBI infants The three techniques mentioned above measure different aspects of auditory function. OAEs evaluate the activity of the cochlear outer hair cells (OHCs) More recently, auditory steady-state responses (ASSR) have been reported as a reliable and objective technique for evaluating hearing thresholds, with the advantage that several frequency-specific thresholds can be assessed simultaneously, and one frequency-specific audiometry can be obtained One treatment for hearing loss is the use of hearing aids (HA), and cochlear implants are employed in selected cases. However, severe and moderate hearing loss may not be identified until the second year of life, and mild hearing loss is usually not detected until the child begins school Therefore, our aim was to analyze the effects of HA use on auditory function as evaluated by modifications in OAEs, ABRs and ASSRs in a group of infants with PBI and severe, profound hearing loss.th week of gestation and 28 days after birth gave rise to abnormal neurological examination and abnormal magnetic resonance image (MRI) findings. All infants underwent a neurological examination in addition to the following evaluations: otoscopy, tympanometry, acoustic stapedial ipsilateral reflex (ASIR), OAEs, ABR, ASSRs and MRI. A total of 13 infants with severe or profound bilateral sensorineural hearing loss were included in this study. The parents of all infants provided written informed consent, and the study was approved by the institutional review board of the Institute of Neurobiology, National Autonomous University of México.Infants with PBI attending a specialized neurodevelopment research unit were included in this study. PBI was suspected when an injury that occurred between the 28The tympanometry test was carried out using MT10 equipment , with a base frequency of 1000 Hz (high frequency tympanometry), maximum pressure of 200 daPa, minimum pressure of −200 daPa, maximum compliance of 2.00 ml, minimum compliance of 0.00 ml, and a unit gradient in ml. The results were considered normal when the output values were as follows: a compliance of 0.3 to 1.3 ml, a pressure of ±50 daPa, and a unit gradient of 1 to 2 ml. The results were classified according to Jerger’s curves as follows: type ‘A’ , type ‘B’ , and type ‘C’  OAEs were elicited with ILO-V6 Otodynamics equipment . The test was performed using a probe with two transducers and one microphone. Transient OAEs (TEOAEs) were produced by a brief click (80 µs) with a peak intensity of 80±5 dB SPL at frequencies of 1000, 2000, 3000, 4000, 6000 and 8000 Hz. The stability and sensitivity of this test is between 90 and 100%. In the distortion product OAEs (DPOAEs), the stimuli consisted of two pure tones (F1–F2) of frequencies ranging from 1000 to 8000 Hz, at an intensity of 70 dB SPL. The stimulus, signal to noise ratio, and emission reproducibility were recorded. A response was considered satisfactory when the signal was 5 dB above noise level with a maximum 60 s response time gate.ABRs and ASSRs were studied in sleeping infants in a soundproof room using the AUDIX system . The ABR test was performed 100 µs monaural rarefaction clicks with intensities between 20 and 100 dB HL (hearing level), with a repetition rate of 11.2 Hz. An average of 2000 stimuli and a sweep time of 15 ms were used. The signal was recorded with an Ag/AgCl electrode disk in Cz with mastoids M1 and M2 as reference; impedance was kept under 5 kOhms in all electrodes. Two channels for ipsi- and contralateral registers were used. Amplifier gain was 100,000, with low-bandpass filters at 100 Hz and high-bandpass filters at 3000 Hz. The latency and amplitude of waves I to V and interpeak latencies I–III, III–V and I–V were obtained. A test was considered normal when the threshold for wave V was 30 dB HL; mild alterations were considered between 40 and 50 dB HL, moderate between 60 and 70 dB HL and severe when the threshold was higher than 80 dB HL.The ASSR study was carried out with intensities between 20 and 100 dB HL in 5 to 10 dB steps. Stimuli were a combination of five carrier tones: 500, 1000, 2000, 4000 and 8000 Hz modulated in amplitude at rates: 95, 98, 101 and 105 Hz. Electrodes were placed in the mastoids (M1 or M2) as an active channel, and Cz was used as reference. Impedance was kept under 5 kOhms in all electrodes. Amplifier gain was 100,000 with low-cut filters at 10 Hz and high-cut filters at 300 Hz; the analysis period was 1.37 ms, and approximately 24 epochs were averaged. The frequency spectrum was obtained with the Fast Fourier Transform. Each spectral peak was considered as a vector in an X–Y coordinate system, where its length represented the amplitude of the spectral peak. The level of significance between the signal and noise spectral components was determined with Hotelling’s T2-test Hearing loss severity was evaluated based on calculated with the pure tone average (PTA) Infants with profound hearing loss used a behind the ear (BTE) hearing aid with digital technology in the right ear; the left ear was not stimulated and was used as a control. The digital BTE hearing aid was adjusted with software  in 6 frequency bands , and the maximum gain was established according to the threshold. To adjust the BTE hearing aids to each particular infant, an instant mold was made for the right ear. Indications for the use of BTE hearing aids were 4 to 6 hours a day in comfort program and volume set to 4 (maximum volume). Statistical analyses of the differences between auditory thresholds at the first and second evaluations of the two ears were carried out using Student’s t-test for paired samples.Of the 378 infants evaluated, only 13 (3.4%) presented bilateral sensorineural severe to profound hearing loss. The study group consisted of 7 females and 6 males; 6 premature infants and 7 full-term infants. Premature infants had a gestational age of 35±1.6 weeks and full-term infants 39.2±1.2 weeks. At the first evaluation, the premature mean age was of 4.4±1.4 months, and the full-term mean age was 4.9±1.7 months. Tympanometry tests were carried out in all infants in the study group, and all results were normal (curve type A). The ASIR was absent in all frequencies evaluated.The TEOAE and DPOAE tests were carried out in all 13 infants. In the basal test, all infants exhibited no response in any of the frequencies. In the second evaluation, after six months of right ear HA use, OAEs showed no significant differences (p>0.05) .In the first evaluation, nine infants (69.2%) exhibited ABRs with mean latency in the right ear as follows: for wave I, 2.66±0.54 ms; wave II, 3.67±1.24 ms; wave III, 5.13±0.98 ms; wave IV, 6.87±0.89 ms; and wave V, 7.36±1.59 ms. Only 4 infants (30.8%) showed an absence of waves I to V when maximum stimulation (100 dB) was applied. In the second evaluation (after right ear HA use), all ABR waves were present in 9 infants (69.2%), and other infants (7.7%) presented waves IV and V; ABRs elicited no response in 3 infants (23.1%). The mean latencies in the right and left ears are shown in In the first evaluation, only 9 infants (69.2%) presented waves I, III and V that allowed the assessment of inter-wave latencies. The mean values for the right and left ears are shown in In the first right ear evaluation, wave V was present in 9 infants (69.2%). To calculate the mean threshold, a numerical value of 110 dB was given to the infants with no response at 100 dB. The mean hearing threshold was 90.0±15.8 dB. In the second evaluation after right ear HA use, a significant decrease to 80.0±19.1 dB (p = 0.003) was observed. In the left ear, 7 infants (53.9%) presented wave V. The mean hearing threshold was 94.6±17.1 dB. In the second evaluation, the threshold decreased to 87.7±17.8 dB (p = 0.069). However, in the first evaluation of the right side, the ratio of wave V absence in preterm/term infants was one:three. On the left side, the no-response ratio observed was three:three. All infants without a response in the initial evaluation had a response in the second evaluation .In the first evaluation, the mean hearing thresholds for the right ear in the frequencies tested were as follows : 500 Hz, 85.0±16.3 dB; 1000 Hz, 83.5±19.1 dB; 2000 Hz, 84.0±16.1 dB; 4000 Hz, 89.2±17.1 dB; and 8000 Hz, 90.4±15.9 dB. After right ear HA use, the mean thresholds of all frequencies decreased to 75.7±26.9 dB, 77.3±17.9 dB, 75.4±21.6 dB, 72.3±27.1 dB, and 79.6±19.6 dB, respectively. Only one significant decrease in the mean hearing threshold in the 4000 Hz frequency (p = 0.013) was found . There wThe aim of this study was to analyze the effects of early HA use (before six months of age) on auditory function in a group of infants. Main finding of our study is that in infants with PBI and severe to profound hearing loss, the use of a HA decreased the hearing threshold evaluated based on ABR and ASSR tests, with no modifications in auditory receptor function, as assessed based on OAEs.All the infants in our study presented with severe to profound sensorineural hearing loss without OAEs in the basal evaluation. The causes of hearing loss in our group of infants with PBI were similar to those found in other studies, and included hyperbilirrubinemia, ototoxic antibiotics, and hypoxic-ischemic encephalopathy We propose that the preserved function of those IHCs may be sufficient for environmental sounds (with the amplification of the HA) to stimulate the receptor, auditory pathways and auditory cortex. This may also explain why infants with severe to profound hearing loss with total damage to the OHCs and partial damage to the IHCs presented no OAEs, and yet IHC and auditory pathway activation were enough to produce action potentials that allowed ABR and ASSR evaluations. In agreement with this concept, Kempt proposes two types of sensory hearing loss, transmissive and transduction types, depending on the alteration of the OHCs or IHCs, respectively Auditory pathway properties were evaluated based on ABRs. These responses were present in nine of 13 infants in the initial evaluation; after six months of right ear HA use, the number of infants with ABR responses was the same. However, in the first evaluation of the right side, the proportion of wave V absence in preterm/term infants was one/three, while it was three/three on the left side. Independent of side or prematurity, all infants without a response in the initial evaluation had a response in the second evaluation. This can be explained as an effect of age, which allows for maturation and better myelination of the auditory pathways with the appearance of ABR in the second evaluation.When the hearing thresholds were compared, the right side decreased 10 dB with no significant changes in the latencies or amplitudes of Waves I to V. In the left ear, no significant decrease in the hearing threshold was observed between the two evaluations. Therefore, we postulated that the effect observed on the right side was due to the six months of HA use. It is possible that hearing pathway maturation has some contribution to this effect, as was observed in the analysis of the proportion of ABR absence.Although many studies have been carried out to analyze plastic reorganization of auditory cortex after experimental and human hearing loss and subsequent correction with cochlear implants; only a few studies have analyzed the plastic changes of auditory pathways after HA The decrease in hearing threshold observed with ABRs was also found for ASSRs, where the hearing threshold in the 4000 Hz frequency decreased from 89 dB to 72 dB after right ear HA use. This finding is relevant because it is known that the hearing threshold obtained with ABRs only evaluates a narrow frequency spectrum, between 2000 and 4000 Hz. In addition, it has been reported that ABR generators of Wave V are located in the mesencephalic region at the level of the inferior colliculus. Previously published, inconclusive results indicated that ASSR electrical sources might be localized in the brain stem and cortex at the level of left and right supratemporal plane The decrease in hearing threshold found in both tests but only on the right side after HA use suggests an increase in ABR and ASSR amplitude to the same intensity of the stimulus; the increase in amplitude may be due to an increase in the number of auditory pathway fibers synchronically activated or to an increase in synaptic efficacy in some nuclei of this pathway Experimental models of hearing loss have shown decreases in the number or size of neurons in cochlear nucleus and trapezoid body On the other hand, the maturation pattern of electrically evoked auditory brainstem responses in deaf infants during the first two years after cochlear implant has been compared with the ABR maturation pattern of normal hearing infants The present study included a small sample size. As a result, the conclusions should be considered with caution. Additionally, compliance with HA use could only be measured indirectly with mothers’ self-reports of the duration of HA use.In conclusion, auditory function in infants is modified after early stimulation with HA before 6 months of age, causing a decrease in the hearing threshold determined based on ABR and ASSR evaluations, with no modifications in auditory receptor function as evaluated based on OAEs.


Aim of the present study was to evaluate the occurence of a round window membrane rupture and the effects of hearing restoration after exploratory tympanotomy and sealing of the round window (niche) in patients with unilateral sudden deafness.Retrospective analysis of patients’ charts in a tertiary referral center. Charts of 69 patients with sudden deafness followed by exploratory tympanotomy were retrospectively analyzed. Pure-tone audiometry data before and after tympanotomy were compared to determine the outcome of hearing recovery. The postoperative hearing test values were documented 3 weeks after tympanotomy. All surgical reports were reviewed with regard to the surgical technique performed and the intraoperative findings.18.8% of the patients revealed a visible perilymphatic fistula in the round window niche. 89.8% of the patients reported no typical history for a round window membrane rupture. All patients were treated with an exploratory tympanotomy under local anesthesia and an intravenous corticosteroid treatment regimen. The majority of the surgeons used a fat plomb to cover the round window. Postoperative hearing was significantly improved compared to the preoperative hearing test data. No patient showed a worsened hearing curve after the treatment.Most patients suffering from unilateral sudden deafness had no visible perilymphatic fistula. In our study population, the majority of patients reported no typical history of a pressure elevation in the inner ear. Exploratory tympanotomy is a safe procedure that may support hearing recovery in patients with sudden deafness in addition to the established treatment regimen including high-dose steroids. Considerable interest has been shown in sudden sensorineural deafness in recent years, especially since Simmons postulated that this could be caused by mechanical disruption of the membranes in the inner ear ,2. The rA perilymphatic fistula in the middle ear caused by a deficient round window membrane (RWM) can result in the symptoms of hearing loss, tinnitus and vertigo, either solely or in combination. Many of these patients were supposed to have a predisposing incident with consecutive pressure elevation in the inner ear. Otic barotrauma is well-documented in air travel  and diviWhile it appears that vertigo uniformly responds very satisfactorily to operative treatment, the improvement in hearing loss and tinnitus is more difficult to predict ,7. The dRWM defects are difficult to diagnose and no consensus of treatment has been reached . There aAim of our study was to determine the occurence of a RWM rupture in patients suffering from sudden sensorineural hearing loss. The outcome and safety of the exploratory tympanotomy, as well as the material used to seal the round window, were analyzed.Clinical charts of 69 patients with a history of unilateral sudden deafness between 2004 and 2011 were included in the study. Ethics was obtained for the entire study by the Institutional Review Board of the University of Regensburg (11-101-0232).Sudden deafness was defined as sensorineural hearing loss of more than 50 dB HL in three or more contiguous frequencies in pure-tone audiometry as compared to the normal hearing ear. There exist several studies concering the evaluation of the outcome after exploratory tympanotomy. Ul-Mulk et al.  includedPure-tone audiometry (PTA) was used to calculate the thresholds. To calculate the out-of-limits the PTA value was set to 120 dB hearing loss. The improvement was calculated with respect to this value in each frequency.There was no evaluation of PTA values prior to the event of sudden deafness. All patients were treated simultaneously with high-dose steroids. The exploratory tympanotomy was performed within 48 h after diagnosing the severe hearing loss if no improvement of hearing was observed.Clinical presentation including vertigo and tinnitus was documented, but the indication for surgery in all cases was the hearing loss. The complete medical history including noise exposure was reviewed.The surgical reports with respect to the intraoperative findings and the detailed technique of round window obliteration were analyzed.All patients obtained an exploratory tympanotomy under local anesthesia and received a sealing of the round window niche. The procedures were done via an endaural approach to the middle ear after raising a tympanomeatal flap. Using the operation microscope, the chorda tympani was preserved and the auditory ossicles were inspected. In some cases it was necessary to remove parts of the lateral attic wall to obtain a complete overview of the stapes foot plate and the round window niche. The round window membrane is mostly hidden in the depth of the round window niche. That is why false membranes und mucosal folds were removed by the surgeons routinely. Drilling bony overhangs was not part of the procedure regulary.A clearly visible rupture of the RWM with persisting fluid in the round window niche after suctioning was the criterion for a “definite fistula”. Due to the difficulties to categorize a definite fistula in case of missing overview of the complete RWM, the category of “doubtful fistula” was integrated to the study according to Maier  for subjAll procedures were done by three experienced otological surgeons who used the criteria mentioned above for their diagnosis.Statistical analysis was done using the Wilcoxon-Test for the PTA data. Correlations were determined by the Chi-square test.69 charts of patients with a suspected round window membrane rupture were analyzed between 2004 and 2011. The mean age was 56.9 years (17 to 92 years). 30 females and 39 males were included into the study. 56.5% of the cases showed a hearing loss on the left side. 43.5% of the patients had impaired hearing on the right ear. With respect to the whole study population, 44.9% reported vertigo and 50.7% reported a new manifestation of tinnitus.89.8% percent of the patients had no typical history for a round window membrane rupture. 10.2% of the patients reported a typical history with physical exercise (3/69), diving (1/69), head trauma (2/69) or noise exposure (1/69) coinciding with the start of complaints (Table There was a significant correlation (p=0.001) of the age and the amount of the preoperative hearing loss on the affected ear (pearson coefficient=0.467), as well as of the age and the postoperative hearing on the affected ear (pearson coefficient=0.363).There was no statistically significant association between the medical history for a round window membrane rupture and the intraoperative finding (p=0.3). There was no significant correlation of the history of the patient and the diagnosis of tinnitus (p=0.4) or vertigo (p=0.4) preoperatively. There was also no association between the diagnosis of tinnitus (p=0.6) or vertigo (p=0.09) and the intraoperative finding of a perilymphatic fistula.The evaluation of the surgical reports revealed no fistula in 59.4% of the cases, a definite sign of round window membrane rupture with clear fluid in 18.8% and a doubtful perilymphatic fistula in 21.7% of the patients  there was no improvement in hearing observed. 31% of the patients showed a minor improvement in hearing between 5 dB and 20 dB. Postoperative hearing was significantly improved as compared to the preoperative PTA data  showed an improvement in hearing of more than 20 dB postoperatively. The latter 10 subjects in this group revealed no change in hearing after the tympanotomy and none suffered from a worsening in hearing after the treatment. Bone and air conduction were evaluated 3 weeks after surgery. There was no worsening observed postoperatively. 17 patients (41%) with no fistula improved by more than 20 dB after the treatment. There was no significant difference in hearing recovery between the groups of definite, doubtful and no round window membrane rupture.Complications related to the exploratory tympanotomy  could not be observed.Sudden sensorineural hearing loss (SSNHL) is a severe impairment for the affected person. Over the past decades, no specific treatment regimen could be established . One reaAssessment of perilymphatic fistulas remains a diagnostic problem. In our study we had a rate of 22% of doubtful fistulas. Visualizing the round window membrane often demands the removement of false membranes and bony ridges. Exact data on this technical detail were not possible to evaluate retrospectively in all cases. Indirect signs as the observation of persisting fluid in the round window niche were therefore considered as a criterion for the diagnosis of a doubtful perilymphatic fistula in the present study.Whether other methods such as intrathecal fluorescein for perilymph staining are useful in this issue is still unclear . Poe et Only 4 of our patients with a definite or doubtful fistula reported a typical history. One conclusion concerning this observation might be that the patients’ history does not predict the finding of an intraoperative round window membrane rupture. Thus the anamnesis concerning a predisposing incident is not a reliable indication for the surgery.18 patients (26%) had no hearing improvement in the control examination after 3 weeks in our study population. This result is similar to Gedlicka et al. , who perThere was a correlation between the age and the pure-tone audiometry values, which demonstrated that older people had a more severe impairment of hearing pre- and postoperatively. There was no correlation between the history of the patient, the intraoperative finding and the diagnosis of tinnitus or vertigo preoperatively. That means that we could not predict the finding of a perilymphatic fistula. The analysis of our pre- and postoperative pure tone audiometry values revealed significantly improved hearing postoperatively. Almost half of the patients had an improvement of their mean average hearing loss by more than 20 dB. This result might be due to tympanotomy and the covering of the round window niche. But we have to consider other possible effects: All patients were simultaneously treated with intravenous steroids starting with 500 mg prednisone following a reduction scheme over 12 days. Also placebo effects and a spontaneous recovery have to be mentioned and could not be excluded. There is also a possible bias because only patients who consented to perform surgery were included to this study. A generally accepted definition of what constitutes improvement or recovery after a SSNHL is not existingamong studies and reports. One interpretation is an improvement of 20 dB in pure-tone audiometry  as choseWith respect to these limitations, exploratory tympanotomy seems to be a safe procedure, because none of the patients suffered from any major complications or a worsening of hearing afterwards. Concerning the technical issues, most of the surgeons at our institution used fat sealing to cover the round window niche. A variety of other techniques including fat-fibrin-glue  and postThe occurence of a round window membrane rupture in SSNHL patients was under 20% in our study population. The patients’ history did not predict the finding of an intraoperative round window membrane rupture. Thus the anamnesis concerning a predisposing incident is not a reliable indication for the surgery.We found no correlation between the hearing recovery of SSNHL patients with and without perilymphatic leak. Nevertheless, exploratory tympanotomy is a safe procedure that might be a useful addition to high-dose steroids in severe cases of SSNHL. With respect to our results an exploratory tympanotomy should be considered for patients with no improvement of hearing within 48 h after treatment with high-dose steroids and a SSNHL of more than 50 dB HL in three contiguous frequencies. Further prospective studies that compare different treatment regimens are necessary to identify the benefit of an exploratory tympanotomy in patients with sudden deafness.Most patients suffering from unilateral sudden deafness had no visible perilymphatic fistula. In our study population, the majority of patients reported no typical history of a pressure elevation in the inner ear. Exploratory tympanotomy is a safe procedure that may support hearing recovery in patients with sudden deafness in addition to the established treatment regimen including high-dose steroids.There is no conflict of interest. The authors confirm that they do not have any financial relationship concerning this research.FH and TK had the idea for the study and drafted the manuscript. CR, VV and CK perfomed the data collection. CK and FH peformed the statistical analysis and designed tables and figures. JS and TK contributed by supervision and administrative support. All authors read and approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6815/12/14/prepub


Mutations in the RPE65 gene are associated with autosomal recessive early onset severe retinal dystrophy. Morphological and functional studies indicate early and dramatic loss of rod photoreceptors and early loss of S-cone function, while L and M cones remain initially functional. The Swedish Briard dog is a naturally occurring animal model for this disease. Detailed information about rod and cone reaction to RPE65 deficiency in this model with regard to their location within the retina remains limited. The aim of this study was to analyze morphological parameters of cone and rod viability in young adult RPE65 deficient dogs in different parts of the retina in order to shed light on local disparities in this disease. In retinae of affected dogs, sprouting of rod bipolar cell dendrites and horizontal cell processes was dramatically increased in the inferior peripheral part of affected retinae, while central inferior and both superior parts did not display significantly increased sprouting. This observation was correlated with photoreceptor cell layer thickness. Interestingly, while L/M cone opsin expression was uniformly reduced both in the superior and inferior part of the retina, S-cone opsin expression loss was less severe in the inferior part of the retina. In summary, in retinae of young adult RPE65 deficient dogs, the degree of rod bipolar and horizontal cell sprouting as well as of S-cone opsin expression depends on the location. As the human retinal pigment epithelium (RPE) is pigmented similar to the RPE in the inferior part of the canine retina, and the kinetics of photoreceptor degeneration in humans seems to be similar to what has been observed in the inferior peripheral retina in dogs, this area should be studied in future gene therapy experiments in this model. Typical clinical signs include profound night blindness, reduced visual field, severely reduced or absent fundus autofluorescence (FAF) and absent rod ERG recordings Several natural occurring as well as genetically engineered animal models exist for RPE65 deficiency. The RPE65 knockout mouse was generated more than a decade ago, proving the function of the RPE65 protein in supplying 11cis retinal to the photoreceptors All animal models have been employed in the development of a gene therapy approach for the treatment of RPE65 deficiency. Especially the canine model proved to be a valuable tool, representing a model of comparable size and with a similarly developed immune system as in humans Gene therapy studies in over 30 patients resulted in significant improvement in light sensitivity and increase in visual field, indicating a rescue effect for rods Similarly, the reason for the discrepancy in the rescue effect between dogs and humans is unknown. In this regard it should be noted that some differences exist in the superior part of the canine retina, which is normally targeted in preclinical trials, compared to the human retina besides obvious differences such as the lack of a macula region or a foveal pit. First, the superior part of the canine retina is attached to non-pigmented RPE and a unique layer is situated behind the RPE, the tapetum lucidum, which reflects incoming light and thus allows a second passage of photons through the outer segments enabling increased light captivity In this study, we investigated for the first time the state of rod and cone viability in the inferior part of the canine retina and compared the data with the situation in the superior part. We analyzed sprouting of rod bipolar and horizontal cells and observed dramatic sprouting events in the inferior peripheral part of affected retinae while other parts of the retina remained silent. In contrast, while analyzing S- and L/M-cone opsin expression, we found a protection of S- cone opsin expression in the inferior part of the retina, but not in the superior part. This was not the case for L/M cone opsin. These observations indicate pronounced differences in rod and cone viability in the inferior part compared to the superior part of the canine retina, which may have important implications with regard to choosing the ideal treatment area in the canine retinae in order to model the human disease.Local Institutional Animal Care and Use Committee (IACUC) approval was not necessary because the animals were euthanized at the end of original study . Eyes from two wild-type and four RPE65 mutant dogs (18–30 months) were used for the study. The animals were euthanized by intravenous injection of pentobarbital sodium . The eyes were enucleated, the anterior part and the lens were removed, and the eyecups were fixed for 15–30 minutes in 4% paraformaldehyde and cryoprotected in graded sucrose .For cryosections, two different pieces of each retina were excised . One froFor flatmount staining, the nasal part of the retina  was exciThe following secondary antibodies were used: donkey anti-rabbit Alexa 488, donkey anti-mouse Alexa 546 , donkey anti-mouse Cy3 and donkey anti-goat Cy3 . All were diluted 1∶500.Confocal images were taken using a confocal microscope  equipped with Argon and Helium-Neon laser. Images for cone morphology in flatmount preparation were done with a Plan-Apochromat 20x/0.8 . The images for sprouting analyses were taken with a Plan-Apochromate 63x/1.4 objective . For image adjustment Photoshop CS 5 extended  was used.The images for the cone quantification were captured with a Zeiss Axioplan 2 microscope equipped with epifluorescence. Images were taken with a Plan Neofluoar 2.5x/0.075 objective  and afterwards merged in Photoshop CS 5 extended manually to create a map of the retina. The retina map was used to keep the orientation on the preparation for imaging the cones with a Plan Neofluoar 10x/0.30 Ph1 objective .In each region, six z-stacks (containing 4 successive images with 1 µm distance each) were analyzed. Three images contained double labeling with CtBP2 and PKC, and 3 images contained double labeling with CtBP2 and Calbindin. Quantification of sprouting was done using data of CtBP2 staining of all six images, resulting in data from 24 images per retina. Quantification was done using the Cell Counter Tool  of Image J . While going through the Z-stack, each clearly visible CtBP2-positive ribbon synapse was counted once. Contrast and brightness of the images were constantly optimized during counting, without altering the original content.Quantification of ONL thickness was performed using LSM Image Browser software  on the same images where sprouting analysis was done. On each image, the ONL thickness was measured three times at 10 µm distance and the mean values was calculated. Scatter plot with regression curve (first order) was calculated using Sigma Plot.2) was counted with the manual counting tool of Photoshop CS 5 extended. For the L/M-cones, because of the 10 times higher number of counts per image,only an area of 10% (0.06 mm2) was counted. The mean value was calculated for the data of the four affected animals at each position. The mean values of all positions in each region were compared to the healthy control animal with a Mann-Whitney rank sum test using Sigma Plot 12 .To compare the cone distribution in healthy and mutated retinae, the retina was divided into 4 regions . For theTo create the heat maps , an inteTo examine rod bipolar and horizontal cell sprouting as well as cone opsin expression, parts of four affected retinae and one healthy control retina were used as shown in Photoreceptors transmit their chemical signal in the outer plexiform layer (OPL) at the ribbon synapses to the second order neurons . The synaptic ribbons of the photoreceptors can be marked with an antibody against C-terminal binding protein 2 (CtBP2) . The rodThe thickness and the organization of the OPL appear to be unaltered in regions 1, 2, and 3 of affected retinae . The conONL thickness depends on the number of photoreceptor nuclei  and lies in the range of 30 to 70 µm in the healthy retina, depending on the location being in the periphery or central, respectively . In affeFollowing these intriguing results on regional disparities in rod bipolar cell sprouting, we analyzed cone opsin expression in the four different regions of the canine retina. Ninety three areas were analyzed on each retina and the numbers of detectable S- and L/M- cones were visualized on heat maps for absolute and relative loss compared to the healthy retina . The num2, with a peak being in the area around the optic disc (1000–1300 per mm2), representing the visual streak in canids (2) (2), but the reduction is not uniform   and 5A,D uniform  and 5. T uniform  and 5B.  uniform .2) that progressively declines towards the periphery (6000–9000 per mm2) (2) are evenly distributed over the analyzed flatmounts, resulting in a general loss of detectable L/M-cones in all 4 regions at about 60% (58–62%).In healthy retinae, similar to S-cone distribution, the highest number of L/M-cones can be found in the two central regions 2 and 3 (10000–15000 per mmper mm2)  and 5. Iper mm2)  and 5. TTo our knowledge, this study analyzes for the first time rod second order neuron sprouting and the cone opsin expression in RPE65 deficient canine retinae with regard to their location within the entire retina. Concerning sprouting of rod second order neuron processes, a phenomenon attributed to ongoing rod degeneration, we observed dramatic activity in the inferior peripheral retina (region 4), while the rest of the retina had significantly less or absent sprouting activity. This sprouting activity correlates with ONL thickness. In addition, we observed a protection of S-cone opsin staining in the inferior central retina (region 3), while L/M cone opsin loss seemed to be independent of the location.Interestingly, even though the canine retina comprises primarily rod photoreceptors (more than 95%), detailed information about the spatial distribution of degeneration kinetics of these cells in the course of RPE65 deficiency are of limited availability. Initially, the disease in dogs was even considered to be stationary, because no significant degeneration was observed in clinical examinations In a study published by Hernandez et al. (2010) mildly increased dendritic arborisations of bipolar cell into the ONL were observed in affected animals, however information about the localization within the retina and presynaptic elements such as CtBP2 staining is was not given It is currently unknown, whether the sprouting is triggered by the photoreceptor terminals (presynaptic element) or by second order neurons (postsynaptic element). As observed in our study in regions 1 and 4, sprouting is also detectable in healthy retina, which was previously shown in human and murine eyes In current human clinical trials, patients have been treated at ages between 5 and 45 years An alternative hypothesis would be that only successfully treated photoreceptors stay alive and all untreated cells degenerate. In this case, ONL thickness reduction in treated areas would stop eventually in contrast to untreated areas. Only long-term studies in humans will answer this question.The second observation made in our study is a less severe reduction of detectable S-cones in the inferior central region (region 3). The same observation was made, albeit to a lesser extent in both peripheral regions (region 1 and 4).(regions 1 and 4). These three regions are those, which are attached to pigmented RPE. This observation seems to be contradictory to what we observed concerning the sprouting events in the rod pathway, which were highest in retinae attached to pigmented RPE. To make things even more complicated, L/M cone opsin reduction seems to be independent of the location within the retina. One explanation would be that there is a protective agent or mechanism that prevents S-cones from dying. This S-cone protective effect has not yet been reported in the literature, partly because this study is the first one to address this question in the entire canine retina. Mowat et al. (2013) compared the photoreceptor density of affected RPE65 dogs at 3 months and 6.5 years of age, and found a reduction of cone and rod labeling between young and old animals A correlation of S cone protection and pigmentation seems to be possible since the pigment in the RPE cell layer has specific functions such as light absorption and antioxidative activity, both rendering it light protective in vitro after transfection of human and murine cone opsins into COS7 cells and also in vivo in Lrat−/− mice cis retinal deprivation, L/M- and S-cone opsins have different aggregation properties causing accumulation of opsin in the endoplasmic reticulum. This causes activation of the unfolded protein response, which may induce apoptosis. It was shown that, compared to L/M-opsin, more S-opsin accumulated in inner segments and OPL and was co-localized with ubiquitin. This observation could also explain the different kinetics of cone opsin loss observed in our study.One possible explanation that is independent of pigmentation are differences in the intracellular stress response in the two cone photoreceptor subtypes, which was demonstrated by Zhang et al (2011) In this study, we demonstrate that in RPE65 deficient dogs rod second order neuron sprouting is heavily increased in the inferior periphery at two years of age and generally increased in areas attached to pigmented RPE. In contrast, we show that S cone opsin expression is not uniformly reduced, as pigmented RPE seems to preserve S-cone opsin but not L/M-cone opsin expression. As the medical field deals with the results of the RPE65 gene therapy, the data obtained in this study add further information on the pathology in the most relevant large animal model and should be considered when designing further preclinical studies.Figure S1Analysis of sprouting events of horizontal cells. Confocal images are projections of 4 considered images of a z-stack. The ribbon synapses are marked with CtBP2 (red) and the horizontal cells are marked with Calbindin (green). The detected sprouting events are highlighted with white circles. Wild type (WT), outer nuclear layer (ONL), outer plexiform layer (OPL), scale 20 µm.(TIF)Click here for additional data file.


P < 0.05). Therefore, the vestibular hearing can improve the speech processing in the competing noisy conditions. Vestibular hearing in human is evoked as a result of the auditory sensitivity of the saccule to low-frequency high-intensity tone. The objective was to investigate the relationship between vestibular hearing using cervical vestibular-evoked myogenic potentials (cVEMPs) and speech processing via word recognition scores in white noise (WRSs in wn). Intervention comprised of audiologic examinations, cVEMPs, and WRS in wn. All healthy subjects had detectable cVEMPs (safe vestibular hearing). WRSs in wn were obtained for them (66.9 ± 9.3% in the right ears and 67.5 ± 11.8% in the left ears). Dizzy patients in the affected ears, had the cVEMPs abnormalities (insecure vestibular hearing) and decreased the WRS in wn (51.4 ± 3.8% in the right ears and 52.2 ± 3.5% in the left ears). The comparison of the cVEMPs between the subjects revealed significant differences ( Moreover, one examiner by the finger force on their back head has kept the corrected position. The active electrode was placed over the middle portion of the ipsilateral SCM muscle body as this location appears to generate the most reliable and consistent responses. The reference and the ground electrodes were placed over the upper sternum and on the midline forehead, respectively, Curthoys et al. . Auditorn et al. , and Murn et al. .In bilateral case, cVEMPs asymmetry ratio is not calculated. In the control group, this ratio was calculated using the peak-to-peak amplitudes for the right ear and the left ear, respectively. The cVEMPs results for the control group were used as normative data. The normative values for latency and cVEMPs asymmetry ratio were calculated as mean ± two standard deviations, Murofushi et al. . Latencispeech reception threshold (SRT), most comfortable level (MCL), uncomfortable level (UCL), WRS in quiet, and WRS in wn. SRTs were assessed using the standard two-syllable words list . MCL and UCL were determined in the normal range. WRS in quiet was tested using the standard monosyllable phonetically balanced words list. The words were presented by one female (monitoring of live voice), who was the native Persian and had no the dialect. She did not know about the case or the control subjects, and testing was randomized (blind). All subjects (case and control) had normal scores, 96–100%, Brandy [The speech assessments consisted of , Brandy . Indeed,, Brandy . ɑ/). Each list has been made of twenty five monosyllabic words and presented at 10 dB signal to noise ratio  to subjects' ipsilateral test ear at the same time. Regarding the phonological properties of persian language, which have 6 vowels , and depending on frequency characteristics of each vowel (F1) see , Wikipedt-tests and one-way ANOVA for continuous variables and χ2-tests for categorical variables. A P value of <  0.05 was considered to indicate statistical significance.Data were analyzed by unpaired Student's divorce, strife, and death of father.The dizzy patients presented with a total of forty-four ears . The affected ears consisted of benign paroxysmal positional vertigo , migraineurs , vestibular neuritis , and psychogenic causes , which had the symptom of a uniattacked of sudden vertigo during few hours after The diagnosis of patients with BPPV found severe vertigo that lasts for seconds and is provoked by head movements and results of typical nystagmus  and subjective vertigo in the Dix-Hallpike, Barin  and Cha The diagnosis of patients with vestibular neuritis obtained on a history of severe continuous vertigo, they had a feeling of nausea or vomiting. VideoNystagmoGraphy showed a caloric paresis and abnormal head impulse test in the affected ear, Fujimoto et al.  and Cha In migraineurs, vestibular dysfunctions were connected with nystagmus and with episodic vertigo, or a variety of combinations of headache/vertigo. A number of patients reported that their symptoms were worse with achieved head status, but this is not confused with BPPV, since patients with migrainous vertigo were nauseated or phonophobic during attacks, Cha .The diagnosis of psychogenic causes is obtained in the General Health Questionnaire (GHQ), as assigned by Willmott et al. , and theIn dizzy patients, the direction-fixed nystagmus was interpreted to indicate pathology within the peripheral system. Also, the ocular motor evaluation was normal . The other forms of abnormal eye movements were such as pendular nystagmus , Shepard .Therefore, twenty-one patients were ipsilesional affected, and one patient with BPPV was affected bilaterally. Thirteen out of twenty-one unilateral cases were affected on the right side and eight on the left side.μv. The mean cVEMPs asymmetry ratio was 6.5 ± 10.2%, and the upper limit for this ratio (two standard deviations above the mean) was 26.9%. A recording from a normal subject is given in Testing of cVEMPs was done in both ears of each control subject (20 right and 20 left ears). The latency and the amplitude values of cVEMPs were detectable in all healthy persons (40 ears with safe vestibular hearing). The mean latency values for p13 and n23 were 12.7 ± 1.0 and 20.1 ± 2.2 ms, respectively . Therefoμv. In the migraineurs, the mean latencies at p13 and n23 were 15.77 ± 1.36 ms and 25.33 ± 0.55 ms, respectively. The mean peak-to-peak amplitude was 23.8 ± 1.9 μv. In the psychogenic subjects, the mean latencies at p13 and n23 were 14.9 ± 1.5 ms and 24.8 ± 1.2 ms, respectively. The mean peak-to-peak amplitude was 25.3 ± 2.1 μv  were included: both decreased amplitudes and delayed latencies in twelve  and absent responses in eleven . In the BPPV group, the mean latencies at p13 and n23 were 15.12 ± 1.33 ms and 24.69 ± 1.19 ms, respectively. The mean peak-to-peak amplitude was 24.6 ± 1.4 ± 2.1 μv .P < 0.05 for both). The mean peak-to-peak amplitude in the affected ears was significantly lower than that in the control group (P < 0.05). A recording from a dizzy patient is given in In all dizzy patients, the cVEMPs asymmetry ratio findings indicated depressed response on the side with lower amplitude findings in a single ear only. The mean p13 and n23 latencies in the affected ears were both longer than the respective means in the control group; also, the differences were significant (P > 0.05) between the healthy subjects and unaffected ears of the dizzy patients, whereas the dizzy patients in affected ears had decreased WRS in wn . Word recognition scores in white noise (WRSs in wn) at the affected ears of the dizzy patients on the right is given in P > 0.05) between the affected ears on monosyllabic words lists. However, the recognition rates of vowels heavily depend on the duration of their phonemes [WRS in wn obtained for all healthy subjects  and the upper limits (mean + two standard deviations) for the right ears and the left ears was 85.5% and 91.1%, respectively. There were no significant differences (phonemes . Word reP < 0.05). Thus, safe vestibular hearing improved word recognition scores in white noise, and insecure vestibular hearing decreased word recognition scores in white noise.Our main outcome measures were differences in amplitudes, p13 - n23 latencies of the cVEMPs between affected ears (23 ears with insecure vestibular hearing and worse WRS in wn), and unaffected ears (21 ears with safe vestibular hearing and better WRS in wn), respectively. Comparison of the cVEMPs at affected ears versus unaffected ears and the normal persons revealed significant differences  and nonfundamental frequency tones, whereas under conditions favoring perception of two separate auditory signals (listening in noise), auditory neurons respond only to F0 tones, Fishman and Steinschneider , Abrams The low-frequency components in speech , as assigned by Mukari and Mamat  which seIndeed, in a clamor situation, better vestibular hearing can help to sound localization on interaural time difference (ITD), which is effective at low frequencies, Tom and Shigeyuki  and May In addition, babies do use pitch variations (the range of vestibular hearing) to segment words, Hartley and King , and, in


Echinometra lucunter is a common American sea urchin responsible for the majority of the marine accidents in Brazil. Although not lethal, these accidents are reported to be extremely painful. Recently, our group described the presence of toxins in its spines that contribute to the pathological reactions. Additionally, we have observed that the E. lucunter spines can regenerate when broken. In the present work we evaluated the enzymatic activities of sea urchin spine extracts in order to identify an enzyme that could contribute not only to the toxicity, but also participate in the spine growth and regeneration.The spine aqueous extract was tested for peptidase activity, with synthetic substrates, in the presence and absence of inhibitors and activators. For proper enzyme classification, the FRET-substrate cleavage pattern, pH-dependency activity and Western-blot analyses were performed. The spine extract was able to cleave Z-R-MCA and Abz-GIVRAK(Dnp)-OH following pre-incubation with DTT, and was inhibited by E-64. Furthermore, the double-peaked pH curve (5 and 7) and the cleavage site proportion  indicate the presence of both mono and dicarboxypeptidase activities. Moreover, in Western-blot analysis, the spine extract was positive for anti-cathepsin B antibody.E. lucunter spines extracts presented a cysteine peptidase activity that was identified as cathepsin B/X that would participate in the remodeling and growth processes of the spine, as well as in the inflammatory response to the accident. Cathepsin cysteine peptidases belong to the C1 cysteine peptidase family of the CA clan, which is also known as the papain family, and comprise a large number of enzymes from both prokaryotes and eukaryotes -4.These enzymes constitute major components of the lysosomal proteolytic system responsible for protein degradation and turnover, playing an important role in maintaining homeostasis in organisms. Movement of lysosomal cathepsins towards the cell membrane or their secretion outside the cell may lead to degradation of the extracellular matrix. This process is usually pathological and contributes to the development of many serious human diseases such as cancer, arthritis, osteoporosis, Alzheimer's disease, multiple sclerosis, inflammation etc. ,4.Cathepsin X  – previously known as carboxypeptidase LB, cathepsin IV, cathepsin B2, cathepsin P, cathepsin Y, cathepsin Z, cathepsin Z1, CTSZ g.p., cysteine-type carboxypeptidase or lysosomal carboxypeptidase B – is a carboxypeptidase that preferentially degrades substrates as carboxymonopeptidases. It cleaves substrates containing Arg at the antepenultimate position as carboxydipeptidases, demonstrating a very unusual switching between monopeptidyl and dipeptidyl peptidases, hence its initial name cathepsin B2. Moreover, it exhibits little or no endopeptidase activity, another reason for such assessment ,6.23 of cathepsin X occupies a region in space which partially overlaps His110 of cathepsin B, a residue considered to be responsible for the exopeptidase activity of the latter enzyme. Cathepsin B is known to hydrolyze substrates through a dipeptidyl carboxypeptidase pathway, and also displays a lower but significant endopeptidase activity  were employed for exo- and endopeptidase activity, respectively. The assay was performed in 100 mM CH3COONH4, containing 200 mM NaCl, pH 4.5 and the fluorescence was measured at λex 320 nm λem = 420 nm in a SpectraMax® M2 spectrofluorimeter , in a 1 cm path-length cuvette. The increase in fluorescence with time was continuously recorded for up to ten minutes. The aqueous extract was also assayed over FITC-conjugated casein, as described by Twining ; 59.358 kDa cathepsin B from the same alga [Uniprot D8LG82] and 65.836 kDa cathepsin B from Trichinella spiralis (a nematode parasite) [Uniprot E5SL05]. The same antibody used in WB was used in immunohistology  are being secreted, probably from these cells [It has been reported that venomous animals contain protein secretory cells, which secrete venom as a defense mechanism. Moreover, we reported toxic effects of inflammation and pain of this se cells .E. lucunter spine extracts showed a proteolytic activity that, based on the selected experiments , could be classified as cathepsin B/X, due to its particular substrate cleavage pattern. This enzyme ought to participate in the remodeling process and growth of the spine and may behave as a toxin as well.In conclusion, E. lucunter sea urchins were approved by the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) under license number 13852-1.The collection and study of The authors declare that there are no competing interests.JMS, Ph.D. student from the University of São Paulo, collected the sea urchins and carried out experiments of purification, Western blotting and kinetic assays; MMA and ACM performed the histology and immunohistochemistry experiments. DCP designed the work and supervised the conduction of most experiments. All authors contributed to the final manuscript. All authors read and approved the final manuscript.


Deficits in central auditory processing may occur in a variety of clinical conditions including traumatic brain injury, neurodegenerative disease, auditory neuropathy/dyssynchrony syndrome, neurological disorders associated with aging, and aphasia. Deficits in central auditory processing of a more subtle nature have also been studied extensively in neurodevelopmental disorders in children with learning disabilities, ADD, and developmental language disorders. Illustrative cases are reviewed demonstrating the use of an audiological test battery in patients with auditory neuropathy/dyssynchrony syndrome, bilateral lesions to the inferior colliculi, and bilateral lesions to the temporal lobes. Electrophysiological tests of auditory function were utilized to define the locus of dysfunction at neural levels ranging from the auditory nerve, midbrain, and cortical levels. Audiological evaluations typically involve assessment of sensitivity for pure tones which is summarized on an audiological record or audiogram. For most patients, the demonstration of normal peripheral auditory sensitivity suggests that auditory function is most likely adequate for speech and language development and communication; a normal audiogram is typically taken as indicative of normal auditory function for educational and communicative purposes. However, for many patients with neurological disease or dysfunction, a normal audiogram does not predict how the patient functions in every day listening conditions . In the Patient CF was a 7 year old who was thought to have had normal hearing until he failed a school screening and a subsequent screening in his pediatrician's office for his left ear. He was functioning above grade level academically. Speech articulation was good and there were no behavioral concerns. He was the result of a 31-week gestation, weighing 3.5 lbs at birth. The pregnancy was complicated by preeclampsia and administration of medication for hypertension. He remained in the NICU for 6 weeks. He experienced bradycardia and acid reflux. He had previously passed newborn hearing screenings utilizing measurements of otoacoustic emissions for both ears. An audiogram  was obtaCF was unable to repeat any words spoken to his left ear even at markedly elevated intensity levels. Tympanometry was within normal limits for both ears. Acoustic reflexes were present for ipsilateral stimulation of the right ear for pure tone stimuli (500–4000 Hz) but were absent at equipment limits for the left ear. Transient-evoked otoacoustic emissions were present for stimulation of both ears. Due to the discrepancy between pure tone sensitivity findings indicating the presence of a severe hearing loss, poorer speech processing than would be expected, and the presence of otoacoustic emissions, measurements of the auditory brainstem response were undertaken. The ABR showed markedly abnormal waveform morphology for stimulation of the left ear as shown in  GW sustained a closed head injury when he was involved in a motor vehicle accident as a restrained driver at age 23. Upon arrival at the emergency room, he was unresponsive and intubated and had a Glasgow Coma Scale of 3. An initial brain scan revealed acute subarachnoid hemorrhage involving the frontal lobes bilaterally as well as further hemorrhage into the quadrigeminal plate cistern with bilateral damage to the inferior colliculi. There was also some extension of the hemorrhage into the left lateral ventricle. In addition, GW sustained an orbital fracture. A swallow study revealed markedly abnormal oral and pharyngeal phases of swallowing with aspiration with thick puree and thin liquids. Speech was severely dysarthric and GW is confined to a wheelchair as he is unable to ambulate. An audiological evaluation revealed the presence of a severe hearing loss for pure tones for both ears as shown in Speech audiometry was attempted but could not be completed as the patient was unable to repeat spondaic words or point to pictures of spondaic words for stimulation of either ear. He reported that he could detect the words but could not understand any of the words. Results of ABR testing indicated the presence of abnormal waveform morphology for stimulation of both ears. ABR data are shown in Tympanometry revealed normal mobility/pressure for both ears, indicating the presence of normal middle ear function bilaterally. Acoustic reflexes were present at normal intensity levels for all stimulus conditions for ipsilateral and contralateral stimulation of both ears. Findings indicated the presence of intact structure and/or function in afferent and efferent neural elements mediating the acoustic reflex arc at brainstem levels. Measurement of transient-evoked and distortion product otoacoustic emissions were undertaken for stimulation of both ears. Robust TEOAEs and DPOAEs were present for stimulation of both ears and GW's DPOAEs are shown in GW was diagnosed with a neural hearing loss secondary to bilateral damage to the inferior colliculi. Amplification was attempted but GW received no benefit from hearing aids. GW was referred to an assistive technology service for assistance in establishing a communication system. Patient CF was a normally functioning middle school age child until he was struck by a motor vehicle while riding on a bicycle. He was unresponsive at the scene of the accident with a Glasgow Coma Scale of 3. Magnetic resonance imaging undertaken 10 days after CF's injury showed extensive damage to subcortical and cortical structures including white matter edema of the subcortical medial bifrontal regions, cortical injury to the anterior temporal poles, edema to the left splenium of the corpus callosum, edema of the bilateral caudate nucleus, edema of the right thalamus, edema of the bilateral caudate nucleus, edema of the right thalamus, edema of the posterior limb of the right internal capsule, edema of the left posterior thalamus extending in the lateral midbrain, and edema of the left cerebral peduncle. Unlike the patients discussed above, CF was found to have normal peripheral auditory sensitivity .He was also found to have normal acoustic reflexes for both ipsilateral and contralateral stimulation of both ears and a normal auditory brainstem response .However, the middle latency response was absent for stimulation of both ears. CF experienced marked difficulty in processing speech. He was assessed with a variety of standardized and unstandardized tests of central auditory function as well as electrophysiological measures which have been reported in more detail previously . The midAll of the patients reported above had markedly impaired speech perception despite the presence of normal otoacoustic emissions which is indicative of normally functioning outer hair cells , 5. For The auditory brainstem response was instrumental in diagnosis of the mechanisms underlying the hearing and speech processing deficits for Cases Measurements of the acoustic reflex were also insensitive to the auditory pathology manifested for Cases The diagnosis of ANSD for the left ear in Hearing loss resulting from lesions to the inferior colliculi secondary to head trauma has been reported previously –24. The The presence of acoustic reflexes for The mechanism underlying the speech processing deficits for All of the patients reported upon in the present paper experienced severe speech processing deficits which were bilateral for Cases The cases reviewed in the present paper have a number of implications for audiological practice. Use of otoacoustic emissions for screening of newborns will not identify ANSD in newborns. Given the increased prevalence of ANSD in NICU graduates, the use of ABR screening methods in the NICU is advisable. Comprehensive audiological assessment is recommended in the presence of delays in the acquisition of speech and language skills or failed screenings despite the fact that a child has passed a newborn hearing screening. Provision of hearing aids for patients with auditory disorders as that manifested by


Organic anion transporting polypeptide (Oatp) transporters at the blood–brain barrier (BBB) and the blood-retinal barrier (BRB), which consists of retinal capillary endothelial cells and retinal pigment epithelial cells, are major determinants of the control of anionic drugs into the brain and retina. Although Oatp1a4 (Slco1a4) and Oatp1c1 (Slco1c1) are known to be expressed in the abluminal and luminal membrane of the rat BBB and Oatp1a4 is known to be expressed at the BRB, the expression and localization of Oatp1c1 at the BRB and subcellular localization of Oatp1a4 at the BRB have received little attention. Therefore, the purpose of present study was to determine the cellular and subcellular localization of Oatp1a4 and 1c1 at the BRB.We used guinea pig polyclonal antibodies to Oatp1a4 and 1c1 for immunoblot and immunohistochemical analysis to determine their cellular and subcellular distributions in the rat retina. We compared these distributions with those of the glucose transporter 1 (GLUT1/Slc2a1). Whole brain, brain capillary fractions and kidney were used as control.Oatp1a4 and 1c1 immunoreactivities were detected in the rat retinal capillaries and co-localized with GLUT1, suggesting that both proteins are located on the abluminal and luminal membrane of the retinal capillary endothelial cells. Oatp1a4 and 1c1 immunoreactivities were preferentially detected on the apical and basolateral membrane of rat retinal pigment epithelial cells, respectively, suggesting that Oatp1a4 and 1c1 are localized on the apical membrane and the basolateral membrane of the retinal pigment epithelial cells, respectively.Oatp1a4 and 1c1 are present at the BRB and contribute to the transcellular transport of amphipathic organic anions across the BRB. In the retina, the blood-retinal barrier (BRB), which is formed by complex tight junctions of retinal capillary endothelial cells (inner BRB) and retinal pigment epithelial cells , control the anatomical, biochemical, and transport mechanisms that regulate the access of molecules in the circulating blood to the neural retina ,2. SimilIn vivo studies using microdialysis, have shown that the elimination of amphipathic organic anions, such as estradiol 17-β glucuronide (E17βG) and dehydroepiandrosterone sulfate (DHEAS), from the vitreous humor/retina involves saturable mechanisms E17βG was injected into the vitreous humor, its subsequent elimination from the vitreous humor/retina across the BRB was carrier-mediated, and the elimination was completely inhibited by the presence of probenecid, while digoxin had a much weaker effect [125I]-thyroxin, ([125I]T4) was injected into the carotid artery, the subsequent uptake of [125I]T4 into the brain was inhibited in the presence of 50 μM T4, but not into the retina [4 from the circulating blood. The sensitivity of Oatp1c1 on the luminal and basolateral membrane of the inner and outer BRB is less than that of the BBB. Further studies are needed to determine concentration-dependent inhibition of the uptake of [125I]T4 by the retina or brain.Oatp1a4 and 1c1 mediate the cellular uptake of amphipathic organic anions from the brain side and the blood side of the BBB ,19. In tr effect . Our imme retina , suggestOatp1a4 and 1c1 are respectively localized on both the abluminal and luminal membrane of rat retinal capillary endothelial cells, and on the apical and basolateral membrane of the RPE. Our results support the hypothesis that Oatp1a4 and 1c1 contribute to the transcellular transport of amphipathic organic anions across the BRB in both the blood-to-retina and retina-to-blood directions.BBB: Blood–brain barrier; BCSFB: Blood-cerebrospinal fluid barrier; BRB: Blood-retinal barrier; CH: Choroid; Cx: Cerebral cortex; DHEAS: Dehydroepiandrosterone sulfate; E17βG: Estradiol 17-β glucuronide; GCL: Ganglion cell layer; GLUT1: Glucose transporter 1; GST: Glutathione S-transferase; INL: Inner nuclear layer; IPL: Inner plexiform layer; Oatp: Organic anion transporting polypeptide; ONL: Outer nuclear layer; OPL: Outer plexiform layer; PBS: Phosphate-buffered saline; POS: Photoreceptor outer segments; RPE: Retinal pigment epithelial cells; SDS: Sodium dodecyl sulfate; T4: L-thyroxin; TBS: Tris-buffered saline.The authors declare that they have no competing interests.SA carried out the animal studies, data analysis, and the manuscript preparation. SH carried out the antibody’s preparation and animal studies. MT carried out the antibody preparation and helped to draft the manuscript. KH supervised the study design and manuscript preparation. All authors read and approved the final manuscript.


Objective. To explore possible corelationship between the cochlear nerve deficiency (CND) and unilateral auditory neuropathy (AN). Methods. From a database of 85 patients with unilateral profound sensorineural hearing loss, eight who presented with evoked otoacoustic emissions (EOAEs) or cochlear microphonic (CM) in the affected ear were diagnosed with unilateral AN. Audiological and radiological records in eight patients with unilateral AN were retrospectively reviewed. Results. Eight cases were diagnosed as having unilateral AN caused by CND. Seven had type “A” tympanogram with normal EOAE in both ears. The other patient had unilateral type “B” tympanogram and absent OAE but CM recorded, consistent with middle ear effusion in the affected ear. For all the ears involved in the study, auditory brainstem responses (ABRs) were either absent or responded to the maximum output and the neural responses from the cochlea were not revealed when viewed by means of the oblique sagittal MRI on the internal auditory canal. Conclusion. Cochlear nerve deficiency can be seen by electrophysiological evidence and may be a significant cause of unilateral AN. Inclined sagittal MRI of the internal auditory canal is recommended for the diagnosis of this disorder. Auditory neuropathy (AN) is a clinical syndrome characterized by the absence of, or the grossly abnormal, auditory brain stem response (ABR) in the presence of normal outer hair cell function as revealed by otoacoustic emission (OAE) and/or cochlear microphonic (CM) . Most ANA retrospective review was undertaken at the First Affiliated Hospital of Nanjing Medical University. During the study period of August 2009 to August 2010, 85 patients  with unilateral profound sensorineural hearing loss were used to construct a detailed database including clinical manifestations, audiological characteristics, and radiological findings. Eight patients (9.4%) with electrophysiologic responses characteristic of AN were identified as unilateral cochlear nerve deficiency on MRI.μsec click-evoked ABR was recorded using a band pass from 100 to 3000 Hz and in a 10 ms time window with 1024 averages. Click stimuli were rarefaction and condensation clicks presented at the rates of 11.1 per second. The ABR was undertaken using an ICS CHARTR EP system and was considered absent if there was no repeatable response to click stimulus at 97 dB nHL, the maximum intensity of the equipment, and normal if a response was present at lower than 30 dB nHL. CM was obtained simultaneously with ABR tests. The most direct method of separating the CM and ABR is to compare responses obtained with rarefaction polarity stimuli with those obtained with condensation stimuli as described by Berlin et al. [ Puretone audiometry was performed using Madsen Orbiter 922 in a soundproof room. Hearing impairment was defined as the level of Puretone thresholds averaged at 0.5, 1, 2, and 4 kHz. Hearing loss of 26–40 dB was considered mild, 41–60 dB, moderate, 61–80 dB severe, and more than 80 dB profound. Tympanograms and acoustic reflex thresholds were measured using a Madsen Zodiac 901 Middle-Ear Analyzer. Tympanometry was obtained using a 226 Hz probe tone, with a sweep pressure start point of +200 daPa and an end point of −400 daPa. Ipsilateral and contralateral acoustic reflexes were assessed bilaterally with Puretone activator stimuli of 0.5, 1, 2, and 4 kHz. Transient EOAE (TEOAE) and distortion product EOAE (DPOAE) were recorded separately by Madsen CAPELLA systems. TEOAE was measured using click stimuli with a nonlinear mode of stimulus presentation and was considered “present” when the signal-to-noise ratio was ≥6 dB and the confidence ratio was 80%. DPOAE was recorded with a fixed ratio of f2/f1 = 1.2 and fixed levels of 65 dB SPL and 55 dB SPL. A DPOAE pass criterium was presented at a particular frequency region when the signal-to-noise ratio was ≥6 dB. The 100 All patients were scanned using SIEMENS TrioTim 3.0T at a resolution of 0.5 mm × 0.5 mm × 0.5 mm. Direct and reconstructed sagittal oblique images of the contents of the internal auditory canal  were obtained perpendicular to the long axis of the internal auditory canals.85 patients with unilateral profound sensorineural hearing loss received hearing tests and an MRI examination. None of the patients had a history of prematurity, hypoxia, hyperbilirubinemia, exposure to ototoxic drugs, or other central nervous system disorders. No one had a family history of hearing loss. Vertigo, tinnitus, and other neuropathies were not reported. Speech and language were well developed. Physical examination revealed nothing remarkable except one case whose ear drum was retracted in the left ear. All patients but one had type “A” tympanogram in both ears. Ipsilateral acoustic reflexes were absent but contralateral was present with affected ear stimulation, contrary to the normal ear. One person had type “B” tympanogram with ipsilateral and contralateralacoustic reflexes were absent in the affected ear stimulation. In all cases ABRs were absent or responded to the maximum output in the worse ear, while being normal in the better one. EOAE and CM were present in seven patients. CM was only recorded in one case with absent EOAE indicating middle ear effusion. The neural responses from the cochlea of the eight patients were absent when viewed by means of the oblique sagittal MRI on the internal auditory canal.  ANs are thought to usually present bilaterally, but recent studies suggest that some AN cases involve only one ear –4, accou A typical AN characteristic is a speech discrimination score out of sync with the level of hearing loss. Recently auditory neuropathy spectrum disorder has taken the place of AN to describe this kind of disease –10. HearN = 2) or absent (N = 7) cochlear nerves on MRI [ Buchman et al. reported that nine (13 ears) of 51 children with ABR characteristics of AN had been identified as having small  , in whicIn conclusion, cochlear nerve deficiency can present with electrophysiological evidence and may be a significant cause of unilateral AN. Inclined sagittal MRI rather than CT scanning plays a very important role in the precise diagnosis of this disorder. As contralateral hearing loss in a progressive manner in a patient with unilateral CND had recently been reported , the con