Expression of praxis induction on cortical excitability in juvenile myoclonic epilepsy

Objective: This study aimed to evaluate the effects of praxis induction on sensorimotor cortical and transcallosal excitability in juvenile myoclonic epilepsy (JME). Methods: A total of 36 subjects (18-62 years) were included. The JME group was screened by video-electroencephalography neuropsychological protocol and divided into JME without praxis induction [JME-WI (n = 12)], JME with praxis-induced seizures or epileptiform discharges [JME-PI (n = 10)], and healthy controls (n = 14). Motor and somatosensory cortical excitability and transcallosal pathways were evaluated through single-pulse transcranial magnetic stimulation (sTMS) and somatosensory evoked potentials (SEPs). Results: Motor and transcallosal excitabilities tested with sTMS were not different in the motor-dominant or non-dominant hemisphere among groups. Significant differences were found in cortical SEP amplitudes in the P27 component of the non-dominant hemisphere (p = 0.03, Cohen's d = 0.98), N35 in the dominant hemisphere (p = 0.04, Cohen's d = 0.96), and P27-35 interpeak amplitude in both somatosensory cortices of the JME-PI group (p = 0.03, Cohen's d = 0.96; p = 0.02, Cohen's d = 1.05) when compared with healthy controls. Giant SEPs were observed in two (16.7%) and five (50%) patients of the JME-WI and JME-PI groups, respectively. Cortical latencies did not reveal differences. Conclusions: Praxis induction was associated with enhanced excitability in the somatosensory cortex of JME patients. Significance: These findings may help clarifying the less favorable therapeutic response in the JME-PI group and indicate identifying praxis induction as an important determinant in differentiating between JME patients. (C) 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.