A Rare Variant of Neuromyelitis Optica

Abstract

Absence of antibodies against Aquaporin 4 (AQP4) in the serum in a case of Neuromyelitis Optica (NMO) is rare. Although the AQP4 +ve variant of NMO is currently considered as a type autoimmune disease (autoimmune astrocytopathy or autoimmune astrocytic channelopathy), the cause of the AQP4 -ve variant is still unknown. Here we present a case of a 28 year old female who presented with sub-acute onset of central vertigo, nystagmus, diplopia and vomiting with recent exaggeration of symptoms and was subsequently diagnosed as case of AQP4 -ve Neuromyelitis Optica. Devic's disease or Neuromyelitis Optica (NMO) is an inflammatory disorder which is aggressive and characterized by recurrent attacks of optic neuritis (ON) and myelitis. The attacks ON is unilateral in some cases of NMO, while in other cases it can be bilateral as well and the attacks of myelitis severe and transverse both of which are rare in multiple sclerosis (MS). Besides, the myelitis in NMO is typically longitudinally extensive, and involves three or more contiguous vertebral segments. Also in contrast to MS, progressive symptoms do not occur in NMO.1 In spite of the fact that differences exist between NMO and multiple sclerosis (MS), the relationship between NMO and MS has been controversial for a long time.2 It is now recognized that in approximately half of the cases there are lesions that involve the hypothalamus thereby causing endocrinopathy, the lower brainstem presenting as interactable hiccoughs or vomiting due to the involvement of the area postrema in the lower medulla; or the cerebral hemispheres producing focal symptoms, encephalopathy or seizures.