Recurrent Longitudinally Extensive Myelitis and Aquaporin-4 Seronegativity - The Expanding Spectrum of Neuromyelitis Optica.

Neuromyelitis Optica Spectrum Disorder (NMOSD) is a recently proposed unifying term for Neuromyelitis Optica (NMO), also known as Devic's disease and related syndromes. It is a relapsing inflammatory demyelinating disease that most commonly affects optic nerves and the spinal cord, leading to sudden vision loss or weakness in one or both eyes, and loss of sensation and bladder function. Though inflammation may also involve the brain, the lesions seen in NMO are different from Multiple Sclerosis (MS) which has a similar clinical course. Attacks of NMOSD tend to be more severe and often different in nature from MS. MS and NMOSD are often confused but require a different course of treatment for optimal results. Here, we describe a patient who had clinical features suggestive of NMO but showed seronegativity for anti-aquaporin antibodies, done twice. Initially he was managed on the lines of MS but showed a deteriorating clinical course on initiation of treatment with interferons. Later, his diagnosis was revised to seronegative NMO and he was started on immunosuppressive therapy with azathioprine to which he showed optimal response and achieved disease stabilization.