BACKGROUND:

Multiple sclerosis (MS) onset before puberty may have a distinct clinical presentation. Pediatric patients with MS may less often meet MRI diagnostic criteria for adults. Whether initial MRI presentation is distinct in prepubertal patients is unknown.

METHODS:

We queried the UCSF MS database for pediatric patients with MS (onset <or=18 years) who underwent brain MRI within 3 months of initial symptoms. The overall number of lesions and the number of well-defined and ovoid, large, confluent, and gadolinium-enhancing lesions were compared between patients with earlier-onset (EOPMS) (<11 years) and later-onset (LOPMS) (>or=11 years) pediatric MS. The next available brain MRI scan was used to evaluate lesion resolution.

RESULTS:

Thirteen children with EOPMS (median age 8.90 years, range [3.58-10.98], 38% girls) and 18 with LOPMS (median age 14.47 years, range [11.78-18.00], 61% girls) were identified. While the overall number of T2-bright lesions was similar in the two groups, patients with EOPMS had fewer well-defined ovoid T2-bright lesions (median = 7, range [0-29] vs 21.5, [4-100]; p = 0.004) and more often had confluent lesions (31% of patients vs 0%; p = 0.02) on their first MRI compared with patients with LOPMS. Ninety-two percent of patients with EOPMS had a reduction in the number of T2-bright lesions on the second scan compared to 29% of patients with LOPMS (p = 0.002).

CONCLUSIONS:

The distinct prepubertal multiple sclerosis (MS) MRI phenotype suggests that underlying biologic processes may differ in earlier-onset pediatric MS compared to later-onset pediatric MS. These findings may delay diagnosis in that age range. MRI criteria for MS diagnosis may need to be revised before puberty.