Facial myokymia in the course of a pontine tumor.

A patient with facial myokymia, suffering from an infiltrating grade II astrocytoma originating within the pons with vegetations invading the cerebellopontine angle, was studied clinically and electromyographically from 1973 to 1979. The myokymias started in the muscles of the right side of the face and later spread to the left side. The latter point is worth noting because the myokymias of the left side were detectable by EMG but not by inspection. They preceded clinical and instrumental evidence of a contralateral spread of tumoral damage to the brainstem. From the physiopathogenetic angle they point up the importance of a mechanism of hyperexcitability and release of the facial motoneuronal pool. The results of the EMG study suggest that the persistence of myokymia, its association with an ingravescent neurogenic impairment of the facial musculature and its polymorphism in the course of pontine tumors are more reliable features than their discontinuity and rhythmicity.