TMS for the Diagnosis and Treatment of Epilepsy

Abstract and Introduction

Abstract

Purpose of review: The aim is to critically review recent advances emerging from the application of transcranial magnetic stimulation (TMS) as a research and clinical tool in the field of epilepsy.

Recent findings: A number of TMS–electromyography (EMG) and TMS–electroencephalography (EEG) studies have identified distinct changes of cortical excitability associated with specific epilepsy syndromes and in asymptomatic siblings of patients with epilepsy. Pharmaco-TMS studies have shed additional light on the effects of traditional and recently introduced antiepileptic drugs on excitatory and inhibitory brain microcircuits as well as cortical plasticity mechanisms. In addition, stronger evidence has emerged that TMS may serve as a biomarker with prognostic (i.e. predicting response to pharmacologic or surgical interventions) and diagnostic potential (for instance aiding in the noninvasive localization of the epileptogenic zone). Finally, the role of repetitive TMS in the therapeutic management of drug-resistant epilepsies and refractory status epilepticus has been further defined and is expected to become more prominent by the optimization of the stimulation parameters.

Summary: TMS has provided important insight into the pathophysiological substrate of human epilepsies and emerges as a valuable tool with diagnostic, prognostic and therapeutic potential. The recent advent of TMS–EEG can be reasonably expected to contribute further significant advances to the field of epilepsy.

Introduction

Transcranial magnetic stimulation (TMS) was discovered in the mid-1980s and rapidly evolved from a simple technique for studying motor pathways to a cutting-edge technology in the field of neurosciences with diverse research, diagnostic and therapeutic applications.

With regard to epilepsy, the applications of TMS can be broadly classified into the following groups: noninvasive investigation of cortical excitability; determination of the effects of antiepileptic drugs (AEDs); noninvasive localization of the epileptogenic zone; and therapeutic management of drug-resistant epilepsies. Recent advances in these research areas are briefly outlined below following a brief methodological introduction.