[Acute foot drop paralysis in multiple sclerosis. Peroneal nerve compression as differential diagnosis of acute...

We report on ten patients with clinically definite multiple sclerosis (MS) and acute weakness during dorsiflexion of the foot and toes. Assuming an attack, two patients were treated with corticosteroids, but without any effect. Since there were very few clinical hints (hyposensitivity in the area of distribution of n. peronaeus superficialis in one, positive Hoffmann-Tinel signs in two cases) only detailed neurophysiological examinations finally resulted in locating circumscribed lesions of the peroneal nerves (mainly localized at the head of the fibula), which consequently ended up in peripheral paresis of the dorsiflexion muscles. In six cases the peroneal lesion was caused by direct pressure on the nerve (hard crossing of the legs in five patients, pressing the caput fibulae against the wheelchair in one), and in the other three cases by stretching of the nerve due to genu recurvatum. Seven patients forced this posture with the intention of compensating for ataxia of the trunk and/or gait. After a period of avoiding these mechanisms, we saw five patients for follow-up examinations with evident improvements in the clinical and neurophysiological aspects.