Marcos Vidal-Dourado, Karlo Faria Nunes, Mirian Salvadori Bittar Guaranha, Lydia Maria Pereira Giuliano, Elza Márcia Targas Yacubian, Gilberto Mastrocola Manzano.

Clin Neurophysiol. 2016 Jul;127(7):2551-60.

doi: 10.1016/j.clinph.2016.03.028.

Abstract

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 (18-62years) 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.