Electrophysiologic investigation of benign eyelid twitching.

A 48 year old woman presented with a 5 year history of intermittent right eyelid twitching. Electromyography of the right lower eyelid revealed myokymic discharges. Blink reflex study revealed a contralateral R1 on stimulating the left, but not the right, supra-orbital nerve. Sensory and auditory evoked potentials were abnormal, pointing to possible brainstem lesions. Oligoclonal bands were present in the cerebrospinal fluid. Magnetic resonance imaging of the brain was normal. This case report demonstrates that benign eyelid twitching can be a localized form of facial myokymia and may be a manifestation of underlying brainstem disease.