Central Nervous System Inflammatory Demyelinating Disorders in the Hong Kong Chinese

Abstract

Central nervous system inflammatory demyelinating disorders (CNS IDD) include classical multiple sclerosis, neuromyelitis optica (NMO) spectrum disorders, a single attack of/recurrent acute disseminated encephalomyelitis, a single attack of idiopathic acute transverse myelitis, optic neuritis (ON) and brainstem encephalitis. CNS IDD are potentially serious disorders with risks of mortality and significant disability. Typical relapsing forms of CNS IDD are relapsing remitting multiple sclerosis and relapsing NMO. Relapsing NMO is typified by recurrent longitudinally extensive transverse myelitis and severe unilateral or bilateral ON. Early diagnosis of CNS IDD is important as long-term treatment for different forms varies. Recognition of clinical, radiological and serological characteristics of different forms of CNS IDD facilitates early diagnoses. A significant proportion of NMO patients are seropositive for autoantibodies against aquaporin-4, the most abundant water channel in the CNS; this supports the hypothesis that NMO is an autoimmune disorder. Is NMO an autoantibody-mediated disorder sharing similar pathogenesis with myasthenia gravis (MG), a classical autoantibody-mediated autoimmune disease? An interesting observation is that paraneoplastic NMO associated various tumours is recognised recently, suggesting similarity with MG which is associated with thymoma in about 15 to 20% of patients.