Drie aspecten in transcraniele magnetische stimulatie: Geluidsmaskering, puls intensiteit en plaatsing van de spoel.

Rationale:

The diagnostic process in epilepsy is often time-consuming
due to the limited sensitivity and the nature of standard EEG recordings. TMS-EEG is a candidate tool to significantly improve the diagnostic efficiency in epilepsy. In this study, we will perform initial measurements in healthy volunteers and epilepsy patients.



Objective:

The main objective is to investigate 3 methodological issues
for TMS-EEG.



Study design:

Interventional study.



Study population:

1. 11 Healthy volunteers, age between 18 and 60 years,
who do not take pro-epileptogenic medication or drugs and without a personal history of epilepsy;

2. 10 Epilepsy patients who have focal
epilepsy.



Intervention:

Healthy subjects: three single-pulse TMS sessions during
one day. Epilepsy patients: one single-pulse TMS session on the first day and three single-pulse TMS sessions on a second day.



Main study parameters/endpoints:

Auditory evoked potential (amplitude), motor threshold (%), TMS-MEP response (amplitude, latency), TMS-EEG
response (amplitude, latency, frequency content).

Before we start with our research on assessing the diagnostic value of TMS-EEG in epilepsy, we perform this pilot study to investigate a number of methodological aspects. To be able to develop a sound protocol these aspects need to be explored in healthy subjects and in patients who already are diagnosed with epilepsy.

Healthy subjects: 1 half day of TMS measurements;

Epilepsy patients: 1 half day of TMS measurements. If they show abnormal responses, there will be a second half day of TMS measurements.

TMS (transcranial magnetic stimulation). The TMS equipment has a maximum output of 1.5 Tesla. The puls duration is 400 microsec. Pulses are given with a frequency of ~0.25 Hz (single pulse TMS).



First, the hot spot and motor threshold of the abductor digiti minimi muscle (ADM) are determined on both sides. In healthy subjects, we stimulate the hot spot in the left hemisphere, while applying 8 different types of noise masking. After that, we stimulate at 7 different intensities and at 8 locations surrounding the hot spot.



In patients, we stimulate 6 different brain areas (hot spot left/right, Brodmann area 19 left/right, epileptic focus ipsilateral/contralateral). If they show abnormal responses, patients return for a second day of measurements. On that day we stimulate at 7 different intensities and at 8 locations surrounding a specific target.