title: Modifications of sleep EEG induced by chronic vagus nerve stimulation in patients affected by refractory epilepsy.
abstract: 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.
authors.affiliation: Sleep Medicine Center, DISMR, University of Genova, Genova, Italy.
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Rizzo
authors.forename: Manolo
authors.initials: M
authors.lastname: Beelke
authors.forename: Fabrizio
authors.initials: F
authors.lastname: De Carli
authors.forename: Paola
authors.initials: P
authors.lastname: Canovaro
authors.forename: Lino
authors.initials: L
authors.lastname: Nobili
authors.forename: Alice
authors.initials: A
authors.lastname: Robert
authors.forename: Pantaleo
authors.initials: P
authors.lastname: Fornaro
authors.forename: Paolo
authors.initials: P
authors.lastname: Tanganelli
authors.forename: Giovanni
authors.initials: G
authors.lastname: Regesta
authors.forename: Franco
authors.initials: F
authors.lastname: Ferrillo
mesh_terms: 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