A longitudinal MR study of the presymptomatic phase in a patient with clinically definite multiple sclerosis.

We describe the dynamics and the nature of the presymptomatic phase of multiple sclerosis (MS) in a patient for whom MR abnormalities suggestive of MS were found before the development of clinical symptoms. The patient was monitored with serial monthly MR imaging of the brain and spinal cord for 5 months. Disease activity during the presymptomatic phase showed imaging characteristics comparable to that of early relapsing-remitting MS in terms of enhancing lesions, duration of enhancement, and new lesions depicted by T2-weighted imaging. Measurements derived from magnetization transfer imaging suggested that the amount and degree of tissue destruction within and outside the lesions revealed by T2-weighted imaging were mild. This, together with the fact that only one of the 43 new lesions that developed during the presymptomatic phase was located in a neurologically eloquent area, may be the reason why, for a relatively long period, the patient had no clinical manifestations of MS despite the marked MR findings of disease activity.