title: Increase of brain-stem high-frequency SEP subcomponents during light sleep in seizure-free epileptic patients.
abstract: OBJECTIVE
  Three hertz spike-and-wave (SW) occurrence is caused by the abnormal functioning of the same thalamo-cortical loop generating sleep spindles. In fact, SW preferably occurs during light sleep and transitional phases of the vigilance status. Since high-frequency somatosensory evoked potentials (HF-SEPs) are powerfully modulated by sleep and arousal, we verified whether they can reveal abnormalities of arousal-related structures in two patients having showed sporadic SW discharges during light sleep.
  
  
  METHODS
  We recorded right median nerve SEPs in two adult patients who suffered since the infancy from childhood absence epilepsy (CAE). Sleep stage-related changes of HF-SEPs were compared to those observed in five healthy volunteers.
  
  
  RESULTS
  HF-SEPs decreased during sleep in controls. By contrast, the amplitude of the subcortical component dramatically increased in CAE patients during phase II NREM sleep. Simultaneous EEG showed normally represented sleep spindles, but not SW discharges.
  
  
  CONCLUSIONS
  HF-SEP increase probably reflects the hyperactivation of brain-stem arousal-related structures. During such a hyperactivation no EEG abnormalities were observed.
  
  
  CONCLUSIONS
  We hypothesize that HF-SEP increase might reflect a protective mechanism against seizure occurrence during light sleep.
authors: Department of Neurosciences, Catholic University, Policlinico A. Gemelli, Largo A. Gemelli 8, 00168 Rome, Italy. drestuccia@rm.unicatt.it
authors: Domenico
authors: D
authors: Restuccia
authors: Marco
authors: M
authors: Rubino
authors: Massimiliano
authors: M
authors: Valeriani
authors: Giacomo
authors: G
authors: Della Marca
mesh_terms: D000328:Adult; D001143:Arousal; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012640:Seizures / Q000503:physiopathology*; D012890:Sleep / Q000502:physiology*