Multiple sclerosis in children under 6 years of age

Objectives: To characterize MS patients with the earliest onset of disease. Background: 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 ex ceptional. Accordingly, inclusion age at onset is generally between 10 and 59 years. Methods: 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). Results: All patients had clinically defined MS according to Po ser'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) a nd carried the most unfavorable prognosis. Among initial symptoms, ataxia w as preponderant (61.%). Optic nerve involvement became more frequent with a ge, Generalized or partial seizures occurred in 22% of cases. First inter-a ttack 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 on set. At follow-up (mean length 6.8 years), the disease was relapsing-remitt ing in 84% patients and the grade of recovery was complete in 64%. Conclusi ons: Definite MS can be consistently diagnosed by current criteria for adul t onset MS in patients with the earliest onset of disease who show peculiar clinical features and natural history. These findings may suggest a recons ideration of current lower limits for MS diagnostic criteria.