Publication date: April 2016
Source:Clinical Neurophysiology, Volume 127, Issue 4
Author(s): F. Giovannelli, A. Borgheresi, L. Tramacere, S. Colon, E. Sirabella, M.P. Viggiano, G. Zaccara, M. Cincotta
The cortical silent period (CSP) following transcranial magnetic stimulation reflects GABAB-mediated inhibition in the primary motor cortex (M1), and could contribute to understand the pathophysiological substrates of epilepsies. Increased CSP duration has been reported in idiopathic generalized epilepsy (IGE) and in partial epilepsy (PE) involving the M1, although other studies yielded discordant findings. In this meta-analysis we systematically assessed the consistency of CSP changes in untreated epileptic patients. We searched for controlled studies evaluating the CSP in drug-naïve or drug-free patients with IGE or PE. The mean difference between CSP duration obtained in patients and controls was calculated. Fourteen studies (267 patients and 234 controls) were included. A significant mean difference was found, with longer CSP in patients than in controls. The difference was still greater if IGE patients only were analyzed. CSP modifications did not depend from differences in motor threshold between patients and controls. Meta-analysis confirms CSP modifications in epilepsies, with enhancement of this cortical inhibitory measure in most IGE patients. This provides a rationale for investigations aiming to verify the hypotheses that increased CSP reflects compensatory neural phenomena counteracting transition from the interictal to ictal state, and that CSP variability reflects the pathophysiological heterogeneity of epileptic syndromes.
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