Clinical and neurophysiological features of familial cortical myoclonic tremor with epilepsy

ABSTRACT Objective Familial cortical myoclonic tremor with epilepsy is a rare epilepsy syndrome. Herein, we report on nine Chinese familial cortical myoclonic tremor with epilepsy pedigrees to delineate its clinical and neurophysiological features. Methods Detailed clinical and neurophysiological data were obtained. Somatosensory evoked potential amplitudes and clinical profile were analyzed using multilevel statistical models. Age‐at‐onset anticipation was analyzed using Kaplan‐Meier survival analysis. Results Fifty‐five patients were interviewed directly, whose mean age at onset of cortical tremor and generalized tonic‐clonic seizures were 31.0 ± 8.3 and 36.0 ± 7.9 years. Giant somatosensory evoked potential was detected in 87.5% (28 of 32) of patients, and long‐latency cortical reflex was detected in 93.5% (29 of 31). Cortical tremor severity was significantly higher in patients with longer disease duration of cortical tremor (P = 0.0061). Somatosensory evoked potential amplitudes were significant higher in patients with higher level of cortical tremor severity (P = 0.0003) and those using antiepileptic drugs (P = 0.0150). Age‐at‐onset anticipation of cortical tremor with paternal transmission was found with statistical significance (P = 0.022). Conclusion We provided the clinical and neurophysiological features of familial cortical myoclonic tremor with epilepsy patients. This study is reported for the presentation of this rare disease in a Chinese population with the largest single report on familial cortical myoclonic tremor with epilepsy worldwide. Age‐at‐onset anticipation of cortical tremor with paternal transmission was statistically significant, which further confirmed a possibility of unstable expanding repeat in the genetic mechanism of familial cortical myoclonic tremor with epilepsy. © 2016 International Parkinson and Movement Disorder Society