New Insights into Neuromyelitis Optica

Abstract

Neuromyelitis optica (NMO) is an idiopathic inflammatory disorder of the central nervous system (CNS) that preferentially affects the optic nerves and spinal cord. In Asia, NMO has long been considered a subtype of multiple sclerosis (MS). However, recent clinical, pathological, immunological, and imaging studies have suggested that NMO is distinct from MS. This reconsideration of NMO was initially prompted by the discovery of a specific antibody for NMO (NMO-IgG) in 2004. NMO-IgG is an autoantibody that targets aquaporin-4 (AQP4), the most abundant water channel in the CNS; hence, it was named anti-AQP4 antibody. Since it demonstrated reasonable sensitivity and high specificity, anti-AQP4 antibody was incorporated into new diagnostic criteria for NMO.The spectrum of NMO is now known to be wider than was previously recognized and includes a proportion of patients with recurrent, isolated, longitudinally extensive myelitis or optic neuritis, and longitudinally extensive myelitis or optic neuritis associated with systemic autoimmune disease or with brain lesions typical of NMO. In this context, a new concept of "NMO spectrum disorders" was recently introduced. Furthermore, seropositivity for NMO-IgG predicts future relapses and is recognized as a prognostic marker for NMO spectrum disorders. Humoral immune mechanisms, including the activation of B-cells and the complement pathway, are considered to play important roles in NMO pathogenesis. This notion is supported by recent studies showing the potential pathogenic role of NMO-IgG as an initiator of NMO lesions. However, a demonstration of the involvement of NMO-IgG by the development of active immunization and passive transfer in animal models is still needed. This review focuses on the new concepts of NMO based on its pathophysiology and clinical characteristics. Potential management strategies for NMO in light of its pathomechanism are also discussed.

Neuromyelitis optica

“…Ratioen kvinner : OVERSIKTSARTIKKEL menn er 3-9 : 1 (3,6). Gjennomsnittlig debutalder er 39 år (7), hvilket er opp mot ti år senere enn for multippel sklerose, men også barn og eldre kan bli rammet (8).…”

“…Det er viktig å kunne skille tilstandene klart fra hverandre, da det er ulik prognose og forskjellig behandlingsregime. Pasienter med neuromyelitis optica har ofte alvorligere symptombilde og dårligere remisjon etter forverringsepisoder enn pasienter med multippel sklerose, dermed også større sekveler og akkumulerende funksjonssvikt (3,25). I tabell 1 presenteres de viktigste forskjellene mellom neuromyelitis optica og multippel sklerose (8,18,23,26).…”

“…Faktorer som taler for residiverende forløp er kvinnekjønn, høy debutalder og komorbiditet med annen autoimmun sykdom (3,9). Det er typisk at symptombildet forverres over dager for så å bli bedre i løpet av uker og måneder, men pasientene får vanligvis restsymptomer.…”

Optic Neuritis Unresponsive to Steroids: Prevalence, Characteristics and Plasma Exchange Treatment

“…This finding explained the development of humoral response against optic nerve, spinal cord and periventricular spaces [6]. Clinical consequences of the NMO are: decrease of visual acuity, amaurosis, paresia or/and sphincters dysfunction, all of them produce a negative influence in physical, emotional, productive and social patient's life [2,3,7,8]. NMO´s acute treatment consists in intravenous methylprednisolone 1 or 2 g per day, 3 to 5 dose.…”

“…Neuromyelitis optica (NMO) is a chronic, demyelinating, inflammatory and autoimmune disease, which major symptoms are optic neuritis (ON) and/or myelitis [1][2][3][4][5]. It is more frequent in African, East-Asian and Latin American, while its prevalence in Europe and North America is low (less than 1 to 4.4 cases per 100,000 inhabitants) [4].…”