A central demyelinating disease with atypical features.

There are clinical, laboratory and imaging criteria to distinguish multiple sclerosis (MS) from neuromyelitis optica (NMO) and acute disseminated encephalomyelitis (ADEM). While MS has unknown aetiology, NMO is commonly associated with vasculitis and ADEM is supposed to be parainfectious in origin. In the present study, six patients are described from a group of 67 with a central demyelinating disorder whose clinical presentation did not conform to existing diagnostic criteria for ADEM, NMO or MS. Their clinical, laboratory and imaging characteristics were studied and analysed. Some features suggested a particular diagnosis but some other features favoured another diagnosis. The features included spinal cord involvement in a large vertical segment with cord swelling, optic neuritis, no lesions in the cerebral cortex, paraplegia with urinary retention during the acute phase, no oligoclonal band in cerebrospinal fluid, absence of any evidence of vasculitis, wide time-gap between spinal cord and optic nerve involvement, good recovery from acute phase of disease and a relatively benign course. We conclude that there exists a subpopulation of patients with central demyelinating disease in this region with mixed clinical features. Overall features suggested either a widened clinical spectrum of MS, NMO or ADEM or a possible overlap between them.