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Expanding the Definition of Neuromyelitis Optica

Adding NMO-IgG as a marker and allowing for brain lesions outside of the optic nerve and spinal cord may permit more timely diagnosis and treatment.

Neuromyelitis optica (NMO; Devic disease or syndrome) is a clinically defined demyelinating syndrome characterized by the simultaneous or sequential development of optic neuritis and acute myelitis. Three recent articles focus on expanding the diagnostic criteria for NMO to include NMO-IgG seropositivity and allowing for lesions outside the spinal cord and optic nerve.

Wingerchuk and colleagues followed 96 patients with NMO and 33 patients with multiple sclerosis (MS). The researchers used likelihood ratios and logistic-regression analyses of clinical criteria to develop a diagnostic model for NMO, on the basis of which they propose revised diagnostic criteria. These include the presence of optic neuritis and myelitis with at least two of the following three supportive criteria: MRI evidence of a contiguous spinal cord lesion three or more segments long, brain MRI nondiagnostic for MS at disease onset, and NMO-IgG seropositivity.

Rubiera and colleagues applied the original 1999 Wingerchuk diagnostic criteria for NMO to 320 patients with clinically isolated syndromes (CIS). Of these patients, 7.2% fulfilled the absolute criteria for NMO at some time; only 1 patient (0.3%) fulfilled one major supportive criterion and could, therefore, be diagnosed with NMO. The authors conclude that the 1999 Wingerchuk criteria lead only infrequently to a diagnosis of NMO in patients with CIS.

In a prospective study of 29 patients with longitudinally extensive transverse myelitis (LETM), Weinshenker and colleagues investigated whether NMO-IgG seropositivity at initial presentation predicted relapse of myelitis or development of optic neuritis. After the first LETM attack, 37.9% of patients were seropositive. After at least 1 year of follow-up in 23 of the patients, none of those who were seronegative experienced a relapse or developed optic neuritis. Of the 11 patients who were seropositive, six developed a second event: Four had recurrent transverse myelitis and two developed optic neuritis. The authors conclude that LETM is a forme-fruste or limited form of NMO, that seropositivity for NMO-IgG in these patients is an indicator of high risk for relapse, and that such patients should be treated with drugs such as azathioprine and prednisone.

Comment: It is becoming clear that neuromyelitis optica is not a syndrome restricted to the optic nerve-spinal cord domain. Demyelination in the brain and, in particular, in so-called MS regions may occur. The identification of patients with NMO and brain white-matter lesions indicates that there is a spectrum of inflammatory demyelinating disease that incorporates MS, NMO, and acute disseminated encephalomyelitis. The phenotype is determined by the genotype and by the immunologic (HLA) environment.

— Girish Modi, MbBCh, MSc, PhD, FCP, FRCP

Dr. Modi is Chief Specialist and Chair, Division of Neurology; and Academic Head, Department of Neurosciences, University of the Witwatersrand Medical School, Johannesburg, South Africa.

Published in Journal Watch Neurology July 18, 2006

Citation(s):

Wingerchuk DM et al. Revised diagnostic criteria for neuromyelitis optica. Neurology 2006 May 23; 66:1485-9.

• Original article (Subscription may be required)
• Medline abstract (Free)

Rubiera M et al. Neuromyelitis optica diagnosis in clinically isolated syndromes suggestive of multiple sclerosis. Neurology 2006 May 23; 66:1568-70.

• Original article (Subscription may be required)
• Medline abstract (Free)

Weinshenker BG et al. Neuromyelitis optica IgG predicts relapse after longitudinally extensive transverse myelitis. Ann Neurol 2006 Mar; 59:566-9.

• Medline abstract (Free)