Modifications of sleep EEG induced by chronic vagus nerve stimulation in patients affected by refractory epilepsy.
OBJECTIVE
The aim of this study was to evaluate the impact of chronic vagus nerve stimulation (VNS) on sleep/wake background EEG and interictal epileptiform activity (IEA) of patients with medically refractory epilepsy.


METHODS
From a broader sample of 10 patients subjected to baseline and treatment polysomnographies, spectral analysis and IEA count have been performed on 6 subjects' recordings, comparing the results by means of statistical analysis.


RESULTS
An overall increase in EEG total power after VNS has been observed, more marked in NREM sleep; collapsing EEG power spectra into 5 frequency bands, we have found a statistically significant increase in delta and theta in NREM sleep, and of alpha in wakefulness and REM sleep. The incidence of IEA is diminished, although not significantly; only the duration of discharges is significantly diminished.


CONCLUSIONS
Long-term VNS produces an enhancement in sleep EEG power of medically refractory epileptic patients. These results may be related to a better structured composition of EEG, and it is possible that chronic VNS may have a major role in enhancing the brain's ability to generate an electrical activity.
Rizzo
Pierpaolo
P
Sleep Medicine Center, DISMR, University of Genova, Genova, Italy.
Beelke
Manolo
M
De Carli
Fabrizio
F
Canovaro
Paola
P
Nobili
Lino
L
Robert
Alice
A
Fornaro
Pantaleo
P
Tanganelli
Paolo
P
Regesta
Giovanni
G
Ferrillo
Franco
F
D000328:Adult; D003700:Delta Rhythm; D004558:Electric Stimulation; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D012890:Sleep; D013826:Theta Rhythm; D014630:Vagus Nerve / Q000503:physiopathology*; D014851:Wakefulness