Trigeminal nerve stimulation does not acutely affect cortical excitability in healthy subjects.
BACKGROUND
Trigeminal nerve stimulation (TNS) has recently emerged as a new therapeutic option for patients with drug-resistant epilepsy but its potential mechanisms of action are not known. Since other antiepileptic treatments have been shown to alter cortical excitability, thereby reducing the liability to seizures, it has been suggested that cranial nerve stimulation such as TNS may act in the same way.


OBJECTIVE
To study whether TNS has the potential to alter cortical excitability in healthy subjects.


METHODS
An adaptive paired-pulse transcranial magnetic stimulation protocol stimulating the dominant hand motor area was used to measure resting motor threshold (rMT), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and long-interval intracortical inhibition (LICI) before, during, and after 40 min of 120 Hz bilateral external continuous trigeminal nerve stimulation. Neuronavigation was used for guidance.


RESULTS
TNS was well tolerated by all subjects. No significant changes were seen in the parameters studied.


CONCLUSIONS
Unlike for example anti-epileptic drugs and the ketogenic diet, trigeminal nerve stimulation does not seem to alter cortical excitability in healthy subjects. This is the first study on cortical excitability in relation to continuous trigeminal nerve stimulation. It still remains to be proven that TNS has the prerequisites to effectively counteract epileptic events in humans.
Department of Clinical Neurophysiology, Uppsala University, Uppsala S-751 85, Sweden.
Hans W
HW
Axelson
Department of Clinical Neurophysiology, Uppsala University, Uppsala S-751 85, Sweden.
Mattias
M
Isberg
Department of Clinical Neurophysiology, Uppsala University, Uppsala S-751 85, Sweden.
Roland
R
Flink
Department of Clinical Neurophysiology, Uppsala University, Uppsala S-751 85, Sweden. Electronic address: asa.amandusson@akademiska.se.
Asa
A
Amandusson
D000328:Adult; D004827:Epilepsy / Q000628:therapy; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006225:Hand / Q000294:innervation / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D038361:Neuronavigation; D050781:Transcranial Magnetic Stimulation; D014276:Trigeminal Nerve / Q000502:physiology*
Epilepsy; TNS; Transcranial magnetic stimulation; ppTMS