Acute Denervation Revealed by Electromyography, in Conjunction With Normal Appearing Lumbar Spinal Cord in <scp>NMOSD</scp> : Case Report

ABSTRACT Background Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disease of the central nervous system (CNS). Segmental denervation has been rarely reported in NMOSD resulting from severe myelitis leading to anterior horn cell loss or inflammatory myeloradiculitis. Case Presentation A 21‐year‐old woman presented due to lower limb dysesthesias evolving to paraparesis and sphincter disorders over a month. Electromyographic examination revealed acute denervation in L5/S1‐innervated muscles with normal peripheral nerve conduction, pointing to anterior horn affection. Magnetic resonance imaging (MRI) showed a lesion at the level of T8‐T9 in the thoracic spine and hypothalami. Serum aquaporin‐4 antibody and cerebrospinal fluid (CSF) oligoclonal IgG bands were positive. The patient improved with intravenous methylprednisolone within 2 weeks. Conclusions Overlapping inflammation of the central and peripheral nervous system can occur in NMOSD. Electromyography could be a helpful diagnostic tool in selected cases of NMOSD in the early diagnostic process, especially in patients with normal MRI findings.