Familial cortical tremor with epilepsy.

We report here on a Japanese family in which five members in three generations developed non-progressive adult onset cortical tremor and epilepsy. Other than tremulous movements resembling essential tremor, the neurologic findings were unremarkable. Electrophysiologic studies revealed giant somatosensory evoked potentials (SEPs), enhanced long latency reflexes (C-reflex), and positive premovement cortical potentials, recorded by jerk-locked averaging, indicating cortical reflex myoclonus. The seizures were sporadic in nature and easily controlled by the anticonvulsants. The tremor also responded well to anticonvulsants such as clonazepam or sodium valproate, but not to beta-blockers. This dominantly inherited disorder should be considered in the differential diagnosis of essential tremor.