[A case of neuromyelitis optica spectrum disorders, with slowly progressive bulbar palsy, mimicking a motor neuron disease].

A 52-year old woman first noted dysphagia four months before admission followed by dysarthria two months later. She then developed weakness of all limbs and became unable to walk. All these symptoms, associated with tongue atrophy, slowly progressed, leading to the initial clinical impression of a motor neuron disease, although her nerve conduction study and electromyography showed no abnormalities. Her brain MRI with T2 weighted/diffusion weighted image (DWI)/fluid attenuated inversion recovery (FLAIR) revealed a high signal lesion located at dorsal medulla oblongata. She proved positive for anti-aquaporin 4 antibody, which confirmed the diagnosis of neuromyelitis optica spectrum disorders (NMOSD). We conclude that NMOSD may initially present with progressive bulbar palsy and pyramidal tract disorder over a few months, mimicking a motor neuron disease. Awareness of this atypical presentation helps establish an early diagnosis of this treatable entity.