Nine MS clinics from the Canadian MS study group collaborated in a retrospective study employing questionnaires about the MS populations and with particular reference to cases with onset before age 16 years. Childhood MS was more frequent in girls and their overrepresentation was even greater in the following subgroups: those with sensory initial symptoms, complete recovery from initial episode, a nonprogressive clinical course, and lower disability scores. Conversely, boys were overrepresented in subgroups of patients with no recovery from the initial episode and progressive course.
MS in girls has an early onset, is usually heralded by sensory symptoms that frequently remit completely, has a relapsing-remitting course and a slow progression. Boys with MS have a poorer prognosis and progressive course, usually related to late onset of the disease. The familial incidence was 28%. CSF showed normal IgG levels in 59% and abnormal oligoclonal bands in 82%. 
COMMENT: MS is probably more common in children than we suspect and the diagnosis should be considered especially in girls with initial sensory or visual symptoms that remit completely and later evolve in a relapsing-remitting manner. An onset at 2 years of age is the earliest case report . The abrupt rise in incidence that coincides with puberty may be related to hormonal factors. Analysis of data from a Faroe Island epidemic of MS suggested a 2-stage process in the pathogenesis of MS: 1) acquisition of an exogenous factor such as infection and 2) the onset of host factors related to pubescence that allow the pathogenesis to proceed .
Oligoclonal bands in the CSF are the best single laboratory test for the presence of abnormal IgG in patients suspected of having MS. A combination of oligoclonal band and IgG synthesis tests is 97% sensitive for probable and definite MS . NMR imaging differentiates between gray and white matter and is superior to CT in the diagnosis of MS.