Newly Developed Urinary Retention and Motor Weakness of Lower Extremities in a Postherpetic Neuralgia Patient
One month before visiting our pain clinic, a 68-year-old female patient with vesicles and pain on the left side around the navel was diagnosed with herpes zoster and received treatment at a local hospital. Although the skin rash improved, the patient, at times, felt squeezing sensations on her left flank. When the patient was referred to the pain clinic, the patient had a squeezing pain and scars of vesicles on the T10 dermatome level on the left side and her numeric rating scale (NRS) was 5 (out of 10). She felt the squeezing pain several times for approximately one minute each time. Aside from a history of hypertension, there was no other unusual medical history or a history of prior surgeries. She was 152 cm tall and 51.2 kg in weight. Laboratory examinations showed no signs of bacteria or viral infection. Complete blood cell count, prothrombin time and activated partial thrombin time tests showed normal results, and there were no abnormal results in the serologic tests (HBs Ag/Ab, HIV Ag/Ab, quantitive VDRL).\nAfter diagnosis of postherpetic neuralgia, the patient received an epidural block once a week for a total of six weeks. We performed the epidural block with 8 ml of 0.8% mepivacaine with the paramedian approach to T10-T11 with the 'loss of resistance' method. Out of six total procedures, only the first procedure included 20 mg of triamcinolone with local anesthetics, and the rest were composed of local anesthetics only. Any signs or symptoms suggestive of dural puncture, such as cerebrospinal fluid (CSF) aspiration through the block needle, headache, paresthesia or sensory impairment were not observed during each epidural block. Pregabalin 150 mg and amitriptyline 5 mg were also prescribed for twice a day. After each epidural block, a pain free period continued for two or three days but she felt numbness like prior to the procedure. Additionally, the squeezing pain reappeared but the pain intensity was reduced to NRS 3. Thus, we expected full recovery by repetitive epidural blocks and by an additional root block or transforaminal epidural block.\nTwo days after the sixth epidural block, the patient was admitted to the department of neurology, through the emergency department, because the patient felt continuous dizziness and motor weakness in both lower extremities. Five days prior to receiving the sixth epidural block, the patient began to feel slightly dizzy. However, the continual dizziness became extreme by the time the patient was admitted to the hospital. Motor weakness of the lower extremities was felt by the patient two days after the final epidural block. In addition, the patient had symptoms of nausea and vomiting. The patient also could not stand or walk alone. The patient's body temperature was 38.3℃ and she did not have any abnormalities on her skin. Physical examination showed a grade III motor weakness in both of the lower extremities, but the deep tendon reflex and cerebellar function tests were normal. Sensory impairment was not observed. She was referred to our pain clinic, because a complication during an epidural block was considered by neurologists. We reviewed the sixth epidural block, examining for any evidence of dural puncture, aspiration of blood and other abnormal events, but there were none. However, in order to be certain, we performed Magnetic Resonance Imaging (MRI) and CSF tests on the first day of admission. The MRI showed no signs of hematoma, abscess, or arachnoiditis (). No bacteria were detected upon CSF analysis. Considering the results, we were able to exclude the possibility of an epidural block complication. The CSF analysis results showed, however, a mild increase in the WBC count (49,000 count/mm3) and a protein level of 97 mg/dl. Virus serology test of the blood and the CSF showed negative anti-IgG and negative anti-IgM antibodies for herpes simplex virus (HSV) and herpes zoster. Two days after the patient was admitted, the patient complained of urinary difficulty and a Foley catheter was inserted, resulting in discharge of 1,200 ml of urine through the catheter. The patient felt squeezing pain on the T10 dermatome level on the left side during her entire stay at the hospital.\nConsidering her clinical progressions and the increase in protein level in the CSF analysis, herpes zoster myelitis was diagnosed by the neurologist and appropriate treatments commenced. Three days after the patient was admitted, the patient was given intravenous acyclovir 1.6 g and dexamethasone 20 mg daily for two weeks. The patient also received exercise rehabilitation treatment while she was on the medication. After receiving treatment for one week, the patient was able to walk but had difficulty in standing up. The patient showed gradual improvement and four weeks later made a full recovery in motor function. The patient's urinary difficulty improved through urinary training and she fully recovered in eight weeks.