[Nuclear magnetic resonance imaging in a case of facial myokymia with multiple sclerosis]

A 59-year-old female of facial myokymia with multiple sclerosis was reported. In this case, facial myokymia appeared at the same time as the first attack of multiple sclerosis, in association with paroxysmal pain and desesthesia of the neck, painful tonic seizures of the right upper and lower extremities and cervical transverse myelopathy. The facial myokymia consisted of grossly visible, continuous, fine and worm-like movement, which often began in the area of the left orbicularis oculi and spread to the other facial muscles on one side. Electromyographic studies revealed grouping of motor units and continuous spontaneous rhythmic discharges in the left orbicularis oris suggesting facial myokymia, but there were no abnormalities on voluntary contraction. Sometimes doublet or multiplet patterns occurred while at other times the bursts were of single motor potential. The respective frequencies were 3-4/sec and 40-50/sec. There was no evidence of fibrillation. The facial myokymia disappeared after 4-8 weeks of administration of prednisolone and did not recur. In the remission stage after disappearance of the facial myokymia, nuclear magnetic resonance (NMR) imaging by the inversion recovery method demonstrated low intensity demyelinated plaque in the left lateral tegmentum of the inferior pons, which was responsible for the facial myokymia, but X-ray computed tomography revealed no pathological findings. The demyelinated plaque demonstrated by NMR imaging seemed to be located in the infranuclear area of the facial nerve nucleus and to involve the intramedurally root.(ABSTRACT TRUNCATED AT 250 WORDS)