title: Risk factors for complications during intracranial electrode recording in presurgical evaluation of drug resistant partial epilepsy.
abstract: BACKGROUND
  Intracranial electrode monitoring is still required in epilepsy surgery; however, it is associated with significant morbidity.
  
  
  OBJECTIVE
  To identify risk factors associated with complications during invasive intracranial EEG monitoring.
  
  
  METHODS
  Retrospective study of all patients undergoing invasive monitoring at Westmead between 1988-2004. From detailed chart reviews, the following variables were recorded: duration of intracranial monitoring, the site of grid implantation, number of grids and electrodes, seizure frequency, postoperative complications and seizure outcome.
  
  
  RESULTS
  Seventy-one patients (median age: 24 years) underwent subdural electrode implantation; 62% had extratemporal lobe epilepsy and 46% were non-lesional. Of the 58 monitored patients who had cortical resections, 45 had good seizure outcomes. Complications related to subdural electrode implantation included transient complications requiring no treatment (12.7%), transient complications requiring treatment (9.9%) and two deaths (2.8%). Specific complications included subdural haemorrhage, transient neurological deficit, infarction and osteomyelitis. The two deaths occurred within 48 h of implantation were related to raised intracranial pressure (one venous infarction, one unexplained). Complications were associated with maximal size of grid (p < 0.001), greater number of electrodes (p < 0.001), electrode density per cortical surface implanted (p < 0.001), right central surface implantation (p = 0.003) and left central surface implantation (p = 0.013). Multiple logistic regression identified larger size grids and right central surface implantation as independent predictors of complications.
  
  
  CONCLUSIONS
  There are significant complications during intracranial EEG evaluations but the majority of these are transient. We found a relationship between the size of the electrode arrays and the incidence of complications. The results of this study have been used to modify our implantation and monitoring protocols.
authors.affiliation: Westmead Hospital, Darcy Road, Westmead, New South Wales 2145, Australia.
authors.forename: Chong H
authors.initials: CH
authors.lastname: Wong
authors.forename: Julie
authors.initials: J
authors.lastname: Birkett
authors.forename: Karen
authors.initials: K
authors.lastname: Byth
authors.forename: Mark
authors.initials: M
authors.lastname: Dexter
authors.forename: Ernest
authors.initials: E
authors.lastname: Somerville
authors.forename: Deepak
authors.initials: D
authors.lastname: Gill
authors.forename: Ray
authors.initials: R
authors.lastname: Chaseling
authors.forename: Michael
authors.initials: M
authors.lastname: Fearnside
authors.forename: Andrew
authors.initials: A
authors.lastname: Bleasel
mesh_terms: D000293:Adolescent; D000328:Adult; D020520:Brain Infarction / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D002540:Cerebral Cortex / Q000503:physiopathology / Q000601:surgery; D004351:Drug Resistance / Q000502:physiology; D004567:Electrodes, Implanted / Q000009:adverse effects / Q000592:standards; D004569:Electroencephalography / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D004828:Epilepsies, Partial / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D004866:Equipment Contamination / Q000517:prevention & control / Q000706:statistics & numerical data; D005260:Female; D006408:Hematoma, Subdural / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D019635:Neurosurgical Procedures / Q000706:statistics & numerical data; D010019:Osteomyelitis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D011183:Postoperative Complications / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D011300:Preoperative Care / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D013530:Surgical Wound Infection / Q000503:physiopathology / Q000517:prevention & control; D016896:Treatment Outcome; D055815:Young Adult