Neuromyelitis Optica

Also known as Devic's disease, neuromyelitis optica (NMO) has been considered a syndrome in its own right or a variant of MS. It has generally been considered a rare disease, but it is unclear if this is because of true rarity vs poor ascertainment methods, or whether its incidence varies by population. It has been estimated to cause about 5% of demyelinating disorders in Japan and India.

All of the criteria listed in Table 6 agree that NMO must present with optic neuritis and myelitis, but the relative timing is not always specified. The addition of neuroimaging criteria, especially the

Table 1

Schumacher Criteria for the Diagnosis of Multiple Sclerosis

1. Neurological examination reveals objective abnormalities of central nervous system (CNS) function.

2. History indicates involvement of two or more parts of the CNS.

3. CNS disease predominately reflects white matter involvement.

4. Involvement of CNS follows one of two patterns:

a. Two or more episodes, each lasting at least 24 hours and at least 1 month apart.

b. Slow or stepwise progression of signs and symptoms over at least 6 months.

5. Patient aged 10-50 years old at onset.

6. Signs and symptoms cannot be better explained by other disease process.

Adapted from Schumacher FA, Beeve GW, Kibler RF, et al. Problems of experimental trials of multiple sclerosis. Ann NY Acad Sci 1965;122:552-568.

Table 2

Poser Criteria for the Diagnosis of Multiple Sclerosis

Clinically definite multiple sclerosis (MS)

• Two attacks and clinical evidence of two separate lesions.

• Two attacks, clinical evidence of one, and paraclinical evidence3 of another separate lesion. Laboratory-supported definite MS

• Two attacks, either clinical or paraclinical evidence of one lesion, and cerebrospinal fluid (CSF) immunological abnormalities.

• One attack, clinical evidence of two separate lesions, and CSF abnormalities.

• One attack, clinical evidence of one, and paraclinical evidence of another separate lesion, and CSF abnormalities.

Clinically probable MS

• Two attacks and clinical evidence of one lesion.

• One attack and clinical evidence of two separate lesions.

• One attack, clinical evidence of one lesion, and paraclinical evidence of another separate lesion. Laboratory-supported probable MS

• Two attacks and CSF abnormalities.

3Paraclinical evidence includes the results of magnetic resonance imaging, evoked potentials, or other diagnostic tests of central nervous system dysfunction.

(Adapted with permission from Poser CM, Paty DW, Scheinberg L, et al. New diagnostic criteria for multiple sclerosis: guidelines for research protocols Ann Neurol 1983;13:227-231, and from John Wiley and Sons.)

requirement that the spinal lesion span several vertebral levels, has helped in excluding cases of MS that clinically present as NMO. The differential diagnosis must also include individuals with a history of isolated optic neuritis who later develop a myelopathy. Care must be taken to ascertain that mass lesions, cervical spondylosis, or other pathological entities have been excluded. Conversely, there may be individuals with incomplete syndromes, such as recurrent optic neuritis or recurrent "transverse myelitis," without other extensive disease who should be considered at-risk for developing NMO. This is important, because the clinical course of NMO is often more virulent than typical MS. The current standard therapy for attack prevention combines oral corticosteroids with immunosuppressive agents, such as azathioprine. Early initiation of therapy is recommended to prevent attack-related disability.

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