A longitudinal fMRI study on motor activity in patients with multiple sclerosis

Using functional MRI (fMRI), patients with multiple sclerosis showed a greater extent of motor activation than controls. Although functional changes are often interpreted as adaptive and as a contributing factor in limiting the clinical deficit, no longitudinal studies have yet been performed for multiple sclerosis. Sixteen patients with multiple sclerosis, two patients with possible multiple sclerosis and nine age-matched controls underwent two fMRI studies with a time interval of 15-26 months. The motor task consisted of a self-paced sequential finger opposition movement with the right hand. Patients with multiple sclerosis exhibited greater bilateral activation than controls in both fMRI studies. At follow-up, patients showed a reduction in functional activity in the ipsilateral sensorimotor cortex and in the contralateral cerebellum. No significant differences between the two fMRI studies were observed in controls. Activation changes in ipsilateral motor areas correlated inversely with age, extent and progression of T1 lesion load, and occurrence of a new relapse. This study may help the understanding of the evolution of brain plastic changes in multiple sclerosis indicating that, in younger patients with a less structural brain damage and benign clinical course, the brain reorganizes its functional activity towards a more lateralized pattern of brain activation. The tendency towards a normalization of brain functional activity is hampered in older patients and in those developing relapses or new irreversible brain damage.