Facial myokymia in syringobulbia.

A patient with a 2-year history of progressive ataxia and tingling in the right hand had prominent facial myokymia. Magnetic resonance imaging revealed syringomyelia and syringobulbia. After successful syringosubarachnoid shunting, the patient died of massive pulmonary embolism. Postmortem examination revealed a syrinx involving the spinal cord and lower half of the medulla; neither the facial nucleus nor facial nerve fibers were directly involved. We hypothesize that interruption of aberrant corticobulbar fibers in the medulla produced disinhibition of a rhythmic neural generator in the facial nucleus.