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Doctors in Brazil and the United States have suggested that optic neuromyelitis (ONM) is a syndrome, not a single disease. They also concluded that the syndrome is not a subtype of multiple sclerosis (MS).
Their investigation of a series of Brazilian patients included 20 women and 4 men, 10 of whom were white and 14 Afro-Brazilian. Two patients had non-recurring acute disseminated myeloencephalitis; one had recurrent disseminated encephalomyelitis; and nine had recurrent ONM syndrome, six with endocrine abnormalities. Between recurrences ONM syndrome improved, in striking similarity to relapsing-remitting MS. However, MS was definitely diagnosed in only four patients.
When the study started 20 patients had affected eyesight. Ten were blind in both eyes and six in one. Blindness was significantly more common and severe in the Afro-Brazilian patients; general disability was significantly worse too. During the study ONM occurred in 18% of recurrences and optic neuritis in 24%; both were more common among the Afro-Brazilians.
The 24 patients were among those with demyelinating diseases treated during 1995–9. The findings were based on a broad range of demographic and clinical characteristics; neurological and pathological features; and necroscopic findings and were compared with findings for demyelinating diseases.
ONM is an expression of many underlying pathological processes which can include those in primary demyelinating diseases; disseminated encephalomyelitis; connective tissue disorders; Hughes syndrome; and endocrine disorders—so it presents a confusing picture. What especially concerns the authors is persistent erroneous reporting of ONM as MS, despite clear differences of their spinal MRI scans.