title: Decision analysis of intracranial monitoring in non-lesional epilepsy.
abstract: OBJECTIVE
  Up to one third of epilepsy patients develop pharmacoresistant seizures and many benefit from resective surgery. However, patients with non-lesional focal epilepsy often require intracranial monitoring to localize the seizure focus. Intracranial monitoring carries operative morbidity risk and does not always succeed in localizing the seizures, making the benefit of this approach less certain. We performed a decision analysis comparing three strategies for patients with non-lesional focal epilepsy: (1) intracranial monitoring, (2) vagal nerve stimulator (VNS) implantation and (3) medical management to determine which strategy maximizes the expected quality-adjusted life years (QALYs) for our base cases.
  
  
  METHODS
  We constructed two base cases using parameters reported in the medical literature: (1) a young, otherwise healthy patient and (2) an elderly, otherwise healthy patient. We constructed a decision tree comprising strategies for the treatment of non-lesional epilepsy and two clinical outcomes: seizure freedom and no seizure freedom. Sensitivity analyses of probabilities at each branch were guided by data from the medical literature to define decision thresholds across plausible parameter ranges.
  
  
  RESULTS
  Intracranial monitoring maximizes the expected QALYs for both base cases. The sensitivity analyses provide estimates of the values of key variables, such as the surgical risk or the chance of localizing the focus, at which intracranial monitoring is no longer favored.
  
  
  CONCLUSIONS
  Intracranial monitoring is favored over VNS and medical management in young and elderly patients over a wide, clinically-relevant range of pertinent model variables such as the chance of localizing the seizure focus and the surgical morbidity rate.
authors.affiliation: Massachusetts Institute of Technology Department of Brain and Cognitive Sciences, Cambridge, MA, USA.
authors.forename: G C
authors.initials: GC
authors.lastname: Hotan
authors.affiliation: Massachusetts General Hospital Department of Neurology, Boston, MA, USA. Electronic address: astruck@mgh.harvard.edu.
authors.forename: A F
authors.initials: AF
authors.lastname: Struck
authors.affiliation: Massachusetts General Hospital Department of Neurology, Boston, MA, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Bianchi
authors.affiliation: Massachusetts General Hospital Department of Neurosurgery, Boston, MA, USA.
authors.forename: E N
authors.initials: EN
authors.lastname: Eskandar
authors.affiliation: Massachusetts General Hospital Department of Neurology, Boston, MA, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Cole
authors.affiliation: Massachusetts General Hospital Department of Neurology, Boston, MA, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Westover
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000627:therapeutic use*; D003661:Decision Support Techniques; D000069279:Drug Resistant Epilepsy / Q000175:diagnosis* / Q000628:therapy*; D000069280:Electrocorticography / Q000009:adverse effects / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D019057:Quality-Adjusted Life Years; D012680:Sensitivity and Specificity; D055536:Vagus Nerve Stimulation / Q000009:adverse effects / Q000592:standards* / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D000927:Anticonvulsants
keywords: Decision Analysis; Epilepsy Surgery; Intracranial EEG; Non-lesional Epilepsy