TMS excitability study in essential tremor: Absence of gabaergic changes assessed by silent period recordings.

Faculty of Medicine

Assiut University

TMS excitability study in essential tremor: Absence of gabaergic changes assessed by silent period recordings.

Research Authors
Khedr EM1, El Fawal B2, Abdelwarith A2, Nasreldein A3, Rothwell JC4, Saber M2.
Research Department
Department of Neurology and Psychiatry
Research Journal
Neurophysiol Clin. doi: 10.1016/j.neucli.2019.05.065. Epub 2019 Jun 2.
Research Member
Ahmed Nasreldein Mohamed Ali
Research Publisher
Elsevier
Research Rank
1
Research Vol
Sep;49(4):309-315.
Research Website
pubmed
Research Year
2019
Research_Pages
309-315.
Research Abstract

Abstract
BACKGROUND:
Essential tremor (ET) is thought to emerge from activity in a distributed cerebello-thalamo-cortical network. It has been proposed that the network goes into oscillation because of abnormal GABAergic inhibitory transmission.

OBJECTIVE:
To test this idea by investigating GABAergic circuitry in motor cortex using transcranial magnetic stimulation (TMS).

METHODS:
Motor cortex excitability was examined using TMS in 21 patients with essential tremor and in 20 control subjects. Resting and active motor threshold (RMT, AMT) and input-output curves examined corticospinal excitability. Contralateral silent period (cSP) at a different range of stimulation intensities, and the ipsilateral silent period (iSP) using a stimulus intensity of 150% RMT were used as measures of GABAergic function.

RESULTS:
RMT and AMT were significantly lower in patients than controls and patients had a steeper I/O curve. However, there were no significant differences in either cSP at different intensities or in iSP.

CONCLUSION:
We found no evidence in favour of the GABA hypothesis in ET.

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