Introduction

Neuromyelitis optica (NMO) is a relapsing demyelinating disorder with a predilection for the optic nerves and spinal cord, associated with autoantibodies to aquaporin-4 (AQP4) water channels in most cases. It affects all races and ages, but has a striking female preponderance and is distinct from multiple sclerosis (MS).

This is a pragmatic guide to treating NMO and the associated NMO spectrum disorders (NMOSDs); these include limited forms of the syndrome, such as recurrent longitudinally extensive transverse myelitis (LETM), recurrent severe optic neuritis (ON) or atypical presentations associated with serum AQP4 antibodies. Because these disorders are rare, there is no available evidence from randomised controlled trials. In contrast to MS, NMO has a high early morbidity and mortality because of severely disabling relapses and lacks a progressive phase. For example, studies report death in 25–30% of patients, after a mean of 5 years from onset.1 ,2 About half of the patients develop significant walking difficulties (at a mean time from onset of 7 years) and many patients become dependent on wheelchairs (figure 1). Visual impairment is also common, with blindness affecting at least one eye in 60–70%, at a mean time from onset of 5 years.1^–3 Although most available studies (observational and retrospective) include patients treated at various times from onset, immunosuppressive treatments clearly dramatically reduce relapses, that is, around a sixfold reduction compared with pretreatment.4^–8 Thus, aggressive treatment of relapses and effective prevention of relapses is the prime aim of treatment and is our single most important message.

For the purposes of this review, we assume that the diagnosis of NMO or NMOSD is correct, and that similar disorders such as MS (for which the treatment is different) are excluded.

The rarity of NMO and the importance of optimising treatment makes specialist input important. In …