Aim: 

We have recently observed in a small sample of healthy subjects that short term trigeminal nerve stimulation (TNS) modulates EEG activity by decreasing the power spectra associated to the background activity, with a most relevant effect in the 10 s time off period. Based on these observations as well as previous data showing that chronic TNS induces a significant reduction of the frequency of the seizures in patients with drug resistant epilepsy, we investigated the effects induced on the EEG activity of patients with refractory partial epilepsy by TNS.

Methods: 

Ten patients (three men and seven women; aged 34–57), with no history of trigeminal neuralgia, participated in the study, after they had given informed consent. Digital EEG signal was acquired before, during and after unilateral and bilateral non-painful transcutaneous electrical stimulation of the supraorbital nerve (SON, n = 5) and of the infraorbital nerve (ION, n = 5) (trains of 120 Hz for 30 sec every 60 sec). EEG spectral analysis based on Fourier Transform was performed at baseline and for three consecutive EEG segments at 10–20–30 sec after TNS. Statistical analysis (ANOVA for repeated measures) was conducted to compare data before and after TNS.

Results: 

The general power spectra was significantly reduced following TNS in comparison to baseline recording. As for the temporal evolution of this reduction, the analysis showed that the most significant effect was at the early intervals of the TNS time off.

Conclusion: 

Short-term TNS modulates EEG activity in epileptic patients by inducing desyncrhonization in accordance with EEG effects induced by vagal nerve stimulation, which is widely used to treat refractory epilepsy. This novel finding opens new prospects in research of alternative non-pharmacological safe treatments for the drug resistant epilepsy.