title: Circadian variation in heart-rate variability in localization-related epilepsy.
abstract: OBJECTIVE
  Case-control studies of sudden unexpected death in epilepsy (SUDEP) have reported that SUDEP is more likely to occur during sleep and thus presumably during night hours. The circadian variation of heart-rate variability (HRV) might be of relevance to this risk. We examined night versus daytime HRV in patients with newly diagnosed and refractory localization-related epilepsy, assessing the effects of drug treatment and epilepsy surgery on the night/daytime HRV ratio.
  
  
  METHODS
  We used spectral analysis to assess HRV and calculated the night-time (00.00-05.00)/daytime (07.30-21.30) ratio of HRV in 14 patients with newly diagnosed localization-related epilepsy before and during carbamazepine (CBZ) treatment and in 21 patients with temporal lobe epilepsy before and after epilepsy surgery. Both groups were compared with age- and sex-matched controls.
  
  
  RESULTS
  No significant differences were found from controls in the night/daytime ratios of HRV whether compared before or after initiation of treatment with CBZ in newly diagnosed epilepsy patients. When patients were used as their own controls, night/daytime ratios of standard deviation of RR intervals (p = 0.04) and total power (p = 0.04) were significantly lower during treatment than before. Compared with those of controls, the night/daytime ratios were lower in epilepsy surgery patients before surgery [low-frequency power (p = 0.04); high-frequency power (p = 0.04)]. Night/daytime ratios did not change significantly after surgery.
  
  
  CONCLUSIONS
  The HRV of the patients was more affected during night-time when the risk of SUDEP seems to be highest in such patients.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden. hakan.persson@karolinska.se
authors.forename: Håkan
authors.initials: H
authors.lastname: Persson
authors.forename: Eva
authors.initials: E
authors.lastname: Kumlien
authors.forename: Mats
authors.initials: M
authors.lastname: Ericson
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Tomson
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use; D002220:Carbamazepine / Q000627:therapeutic use; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology*; D035061:Control Groups; D003645:Death, Sudden / Q000453:epidemiology; D015716:Electrocardiography, Ambulatory / Q000706:statistics & numerical data*; D004828:Epilepsies, Partial / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D000927:Anticonvulsants; D002220:Carbamazepine