Cortical tremor (FCMTE: familial cortical myoclonic tremor with epilepsy).

For 15 years, 50 Japanese and European families with cortical myoclonic tremor and epilepsy were reported in the literature under various names. More recently, the acronym familial cortical myoclonic tremor with epilepsy (FCMTE) has been proposed for this new clinical entity based on both clinical and electrophysiological criteria: irregular postural myoclonic tremor of the distal limbs, familial history of epilepsy, autosomal dominant inheritance, and a rather benign outcome. The diagnosis is confirmed by electrophysiological features favoring cortical reflex myoclonus (enhanced C reflex at rest, giant somatosensory evoked potentials (SEPs), premyoclonus cortical spikes detected by the jerk-locked back-averaging method), and a good response to antiepileptic drugs. The genetic analysis of these families shows heterogeneity with a linkage to chromosome 8q24 for Japanese families, a linkage to chromosome 2p for Italian families, the exclusion of 8q24 locus for a Spanish family, and the exclusion of both loci for a Dutch family. The similarities of this syndrome with the group of myoclonic epilepsy suggest an abnormality of a gene encoding ion channels.