THE LESION CAUSING CONTINUOUS FACIAL MYOKYMIA IN MULTIPLE-SCLEROSIS

Objective: To attempt to identify the site of the lesion causing conti nuous facial myokymia (CFM) in multiple sclerosis (MS) through the use of magnetic resonance imaging (MRI). Design: A case series was employ ed. Setting: The Baird Multiple Sclerosis Center, Millard Fillmore Hos pital, and the Neurology Department, Buffalo General Hospital, Buffalo , NY. Participants and Measures: Twelve patients with MS and CFM were examined by MRI of the brain while the CFM was present. The MRI examin ations were also performed before the CFM had developed and after it h ad ceased in eight of the patients. Another 57 patients with MS who ne ver had CFM but who had similar disabilities to those who did were als o examined by MRI. Results: In 11 of the 12 patients with MS and CFM, the causative lesion was demonstrated to involve the postnuclear, post genu portion of the facial nerve intraaxially in the dorsolateral pont ine tegmentum ipsilateral to the CFM. In the majority of patients who were studied after the CFM had stopped clinically, the lesion was obse rved to resolve on MRI. Seventeen percent of the patients with MS but without CFM were found to have the typical pontine tegmental lesion. C onclusions: Continuous facial myokymia in MS is caused by a pontine te gmental lesion involving the postnuclear, postgenu portion of the faci al nerve. The lesion is identified by MRI in approximately 90% of pati ents with MS who have CFM clinically. The typical MRI lesion may also be found in a minority of patients with MS who do not have CFM clinica lly.