Nuclear facial palsy in multiple sclerosis: a case report

We encountered an unusual case of isolated subacute nuclear palsy of the facial nerve in a 31-year-old man with a 3-year history of clinically established relapsing form of multiple sclerosis. Typical positive sharp waves and fibrillation potentials in the affected facial muscles detected by means of electromyography showed that the lesion was located in the lower motor neuron. Transcranial magnetic stimulation of the cortex could not evoke normal compound motor unit potentials, however, transcranial magnetic stimulation of the facial nerve, which is strongly supposed to depolarize the peripheral nerve in the area of the root exit zone near the internal acoustic meatus, elicited an adequate response. Taking these findings as well as the results of positive magnetic resonance imaging into consideration, we concluded that the clinical symptom was due to a plaque of demyelinization in the nucleus of the facial nerve or in the proximal intramedullary course of facial fibres.