Pediatric sciatic neuropathy presenting as painful leg: A case report and review of literature
A 7-year-old girl with a background of early onset childhood asthma presented with an acute exacerbation of her asthma symptoms. Apart from regular low dose inhaled steroids, she was not on any other medications. Both her past medical and family histories are not significant.\nHer respiratory status gradually deteriorated despite being on intravenous salbutamol, aminophylline, and steroids. She needed intubation and mechanical ventilation for just over 24 hours after which she was successfully extubated and was recovering well.\nFive days later, she reported a burning pain sensation down the whole of the right leg with some sensory disturbance, which she mainly described as “numbness”. A week later, this was followed by weakness of that leg. There was no history of trauma preceding this. Upon clinical assessment, she was noted to have a foot drop with complete inability of ankle dorsiflexion and her right ankle jerk was completely absent.\nShe was only able to mobilize by hopping on her left leg. There was diffuse decreased sensation to pinprick and light touch but mainly from below the right knee to the toes. The rest of the clinical examination was normal.\nExtensive investigations showed a moderate eosinophilia at 1.35 × 109/L (normal range 0.05-1.0) with normal other blood counts and peripheral smear. Her eosinophilia gradually normalized in about 6 weeks. She had a normal full blood count checked prior to this admission. Concomitant with this, the IgE level was also raised at 391 KU/L (normal < 63). Her mycoplasma antibody (genetic prodrug activation therapy-GPAT) level was slightly elevated but this was thought to be of no clinical significance. The throat swab and the Anti-streptolysin O (ASO) titres did no show any evidence of a recent streptococcal infection. Moreover, polymerase chain reaction (PCR) testing for the common respiratory viruses was negative except for rhinovirus. Her auto-antibody screen including Anti-Nuclear Antibody-Hep 2, Centromere antibody, Monoclonal IgA, IgM, and IgG and subclasses, Rheumatoid factor antibody, were normal. Urine and stool culture were negative and the screening for parasites was negative in stool and blood.\nMRI demonstrated enlarged and high signal right sciatic nerve on T2-weighted images. This is seen as far down the nerve in the posterior mid thigh as imaged [Figures and ].\nNeurophysiology examination [] was limited as she was in extreme pain. The study showed features of right sciatic mononeuropathy probably axonal in nature. The peroneal part of the sciatic nerve was more involved. Electromyography could not be performed at the request of mother; therefore, exact site of pathology was difficult to localize.\nInitially, the patient did have daily exacerbations of severe neuropathic pain, which was quite disabling. The pain only responded partially to trials with multiple agents including gabapentin, opiates, and carbamazepine. Fortunately, the pain started to improve after a few weeks and this was also associated with marked improvement of her muscle power. She continued to make good progress and was able to independently mobilize within 5-6 months. A year later, the patient had made a complete motor recovery, although she is left with an area of abnormal sensation affecting the lateral border of her right leg and the dorsum of her foot.