Multiple sclerosis in children under 6 years of age

To characterize MS patients with the earliest onset of disease.MS-primarily a disease of young adulthood-begins in childhood in 3 to 5% of cases. However, onset before 10 years of age is considered exceptional. Accordingly, inclusion age at onset is generally between 10 and 59 years.Information was obtained on patients with MS treated at our institution (n = 6) or from reports in Medline or bibliographies. Onset of disease was before 6 years of age, for a total of 49 patients (29 girls, 20 boys).All patients had clinically defined MS according to Poser's criteria; 22 were also laboratory supported. The female/male ratio (1.4) was lower than that usually recorded for adult onset MS (2.0) and that of MS with onset between 6 and 15 years (2.2 to 3.0). The group of patients (n = 5) with onset before 24 months of age showed the lowest ratio (0.6) and carried the most unfavorable prognosis. Among initial symptoms, ataxia was preponderant (61%). Optic nerve involvement became more frequent with age. Generalized or partial seizures occurred in 22% of cases. First inter-attack interval was less than 1 year in 63% of the cases. The yearly relapse rate ranged from 1.1 at disease onset to 0.2 after 9 years from disease onset. At follow-up (mean length 6.8 years), the disease was relapsing-remitting in 84% patients and the grade of recovery was complete in 64%.Definite MS can be consistently diagnosed by current criteria for adult onset MS in patients with the earliest onset of disease who show peculiar clinical features and natural history. These findings may suggest a reconsideration of current lower limits for MS diagnostic criteria.