title: Brief bursts of pulse stimulation terminate afterdischarges caused by cortical stimulation.
abstract: OBJECTIVE
  To determine whether cortical electrical stimulation can terminate bursts of epileptiform activity in humans, we used afterdischarges (ADs) as a model of epileptiform activity.
  
  
  METHODS
  Cortical stimulation was performed for clinical localization purposes using subdural electrodes implanted in patients undergoing preresection evaluations for treatment of medically intractable seizures. We used 0.3-millisecond pulses of alternating polarity, repeated at 50 pulses/second. When stimulation produced AD, we often applied short additional brief bursts of pulse stimulation (BPS). We examined the effectiveness of BPS in aborting ADs in 17 patients using survival analysis.
  
  
  RESULTS
  With BPS, ADs stopped within 2 seconds in 115 cases, 2 to 5 seconds in 22 cases, and in more than 5 seconds in 89 cases. Without BPS, ADs stopped within 2 seconds in 21 cases, 2 to 5 seconds in 114 cases, and in more than 5 seconds in 340 cases. BPS was an effective method to abort ADs (Cox proportional hazards model: p<0.0001). At any time during the course of ADs, the instantaneous rate of stopping ADs within 2 seconds after BPS was applied was 4.6 times greater than when BPS was not applied (95% CI = 3.7, 5.7). In eight cases, ADs progressed to the occurrence of clinical seizures, always when BPS was not applied.
  
  
  CONCLUSIONS
  Afterdischarges significantly decreased in duration after we applied brief bursts of pulse stimulation. Although afterdischarges are not identical to spontaneous epileptiform activity, these results support the idea that electrical stimulation, applied in an appropriate manner at seizure onset, could abort seizures in humans.
authors.affiliation: Department of Neurology, the Zanvyl Krieger Mind/Brain Institute, The Johns Hopkins University, Baltimore, MD 21287-7247, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Lesser
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: L
authors.initials: L
authors.lastname: Beyderman
authors.forename: D L
authors.initials: DL
authors.lastname: Miglioretti
authors.forename: W R
authors.initials: WR
authors.lastname: Webber
authors.forename: M
authors.initials: M
authors.lastname: Bare
authors.forename: B
authors.initials: B
authors.lastname: Cysyk
authors.forename: G
authors.initials: G
authors.lastname: Krauss
authors.forename: B
authors.initials: B
authors.lastname: Gordon
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology* / Q000601:surgery; D002648:Child; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology; D016019:Survival Analysis; D016896:Treatment Outcome