Transcranial magnetic stimulation in patients with epilepsy

Area of Science:

• Neuroscience
• Epileptology
• Neuromodulation

Background:

• Epilepsy surgery evaluations require precise understanding of epileptic foci.
• Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique.
• The capacity of TMS to modulate epileptiform activity remains under investigation.

Purpose of the Study:

• To investigate the effects of transcranial magnetic stimulation (TMS) on electroencephalographic epileptiform activity in patients with epilepsy.
• To determine if TMS can specifically activate epileptic foci.
• To assess the risk of seizure induction with TMS.

Main Methods:

• Eight patients undergoing epilepsy surgery evaluation received TMS.
• Stimulation parameters included 8- to 25-Hz trains of stimuli.
• A round, water-cooled coil was used, placed over various International 10-20 System positions.

Main Results:

• No seizures or epileptiform discharges were induced from the epileptic focus in any patient.
• One patient with a temporal focus experienced a partial motor seizure from the contralateral hemisphere when stimulated at 100% maximal intensity.
• The study did not find evidence that TMS specifically activates epileptic foci.

Conclusions:

• TMS, under the tested protocols, did not activate epileptic foci in the studied patients.
• High-intensity TMS carries a risk of seizure induction, necessitating precautions.
• Current findings do not support TMS as a method for specifically activating epileptic foci.