The role of transcranial magnetic stimulation in evaluation of motor cortex excitability in Rett syndrome. (July 2016)

• Record Type: Journal Article
• Authors: Krajnc, Natalija; Zidar, Janez
• Is Part Of: European journal of paediatric neurology. Volume 20:Number 4(2016:Jul.)
• Page Start: 597
• Page End: 603
• Publication Date: 2016-07
• Subjects: Rett syndrome -- Transcranial magnetic stimulation -- Motor cortex -- Excitability -- Children; Pediatric neurology -- Periodicals; Nervous System Diseases -- Periodicals; Child -- Periodicals; Infant -- Periodicals; Neurologie pédiatrique -- Périodiques; Pediatric neurology; Electronic journals; Periodicals; Electronic journals; 618.928
• DOI: 10.1016/j.ejpn.2016.03.010
• Languages: English
• ISSNs: 1090-3798

Abstract

Abstract: Rett syndrome (RTT) is a frequent neurodevelopmental disorder confirmed by clinical criteria and supported by the methyl-CpG-binding protein 2 gene (MECP2) mutation. A short central motor conduction time (CMCT) was reported in transcranial magnetic stimulation (TMS) studies performed in RTT. This was attributed to hyperexcitability of the motor cortex and/or spinal motor neurons, but was not studied further. Aim: We performed TMS in RTT to evaluate motor cortex excitability by determining the cortical motor threshold (CMT) and motor cortex inhibition by the cortical silent period (CSP) besides measuring CMCT. Methods: Single-pulse TMS was performed in 17 Rett patients, diagnosed by clinical criteria and MECP2 mutation testing, and the same number of healthy controls. The outcome measures were compared between RTT groups with different antiepileptic drugs (AED) and those with and without the MECP2 mutation. Results: CMCT was shorter, but we found elevated CMT and shorter CSP, which suggests decreased excitatory and inhibitory motor cortical function. The outcome was independent of AED and the presence or absence of the MECP2 mutation. Interpretation: Decreased excitatory and inhibitory motor cortical function could explain the short CMCT, with higher stimulus intensities needed to excite pyramidal neurons. Highlights: Central motor conduction and motor cortex properties in Rett syndrome. Decreased motor cortical function as the underlying mechanism of the short central motor conduction time. Influence of antiepileptic drugs on cortical excitability.