Functional magnetic resonance imaging in multiple sclerosis.

Functional magnetic resonance imaging (fMRI) is a method that combines high anatomical spatial resolution with the ability to localise function. Visual and motor systems are among those that have received most attention. Yet the clinical application is still limited. Recently, some investigators applied fMRI to study patients with multiple sclerosis. Patients with partial motor weakness disclosed a larger area of cortical activation bilaterally by contrast with healthy volunteers when using the affected arm, whereas patients with optical neuritis disclosed a smaller area of activation, when stimulating the affected eye. These results show that different systems might react heterogeneously.