title: Intracranial electroencephalogram to evaluate refractory temporal and frontal lobe epilepsy.
abstract: OBJECTIVE
  We undertook a collaborative study in a multidisciplinary team to channel refractory epilepsy patients to test a hypothesis about placement of intracranial electroencephalography arrays.
  
  
  METHODS
  This was a descriptive case series. Prospective non-invasive presurgical evaluations were based on clinical semiology, magnetic resonance imaging, video-electroencephalography findings and neuropsychological assessments. If the results were discordant, a hypothesis was generated using individualised combinations of positron emission tomography, single-photon emission computed tomography, functional magnetic resonance imaging and Wada tests. The indications for intracranial electroencephalography were: (a) focal magnetic resonance imaging, ictal/interictal scalp electroencephalography with variable results (group A); (b) multi-focal magnetic resonance imaging, focal/multi-focal ictal scalp electroencephalography (group B); (c) non-lesional magnetic resonance imaging, focal/multi-focal ictal scalp electroencephalography (group C). We evaluated whether the seizure-onset zones and eloquent areas were delineated, surgical outcomes (if operated on), and pathology results.
  
  
  METHODS
  A tertiary referral centre for neurology in Hong Kong.
  
  
  METHODS
  A total of 105 refractory epilepsy patients completed non-invasive presurgical evaluations over the period 2007 to 2009. Thirty-two patients were eligible for direct resective surgery, and another 25 patients had a testing hypothesis formulated. Of these 25 patients, 10 were eligible for intracranial electroencephalography based on technical/financial considerations.
  
  
  RESULTS
  All 10 patients (group A=2, group B=4, group C=4) had their epileptogenic zones defined. Six patients underwent functional mapping, all of whom had their eloquent areas defined. Seven of the 10 patients underwent resective surgery; four of them achieved Engel class I/II outcomes. The dichotomised outcomes were 100% (group A), 50% (group B), and 33% (group C) achieving Engel class I/II. Two patients had asymptomatic subdural haematoma. There was no intracranial infection or operative mortality. In five (71%) of seven of the patients, a histological diagnosis was established.
  
  
  CONCLUSIONS
  Proper deployment of intracranial electroencephalography is useful in the presurgical evaluation of patients with refractory epilepsy. This modality of management is potentially of benefit for patients with refractory epilepsy, but is underutilised locally.
authors.affiliation: Division of Neurology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: Lisa
authors.initials: L
authors.lastname: Au
authors.forename: Howan
authors.initials: H
authors.lastname: Leung
authors.forename: Patrick
authors.initials: P
authors.lastname: Kwan
authors.forename: X L
authors.initials: XL
authors.lastname: Zhu
authors.forename: Danny T M
authors.initials: DT
authors.lastname: Chan
authors.forename: H T
authors.initials: HT
authors.lastname: Wong
authors.forename: W S
authors.initials: WS
authors.lastname: Poon
authors.forename: Venus Y H
authors.initials: VY
authors.lastname: Tang
authors.forename: Sam K S
authors.initials: SK
authors.lastname: Ng
authors.forename: Deyond
authors.initials: D
authors.lastname: Siu
authors.forename: Tom C Y
authors.initials: TC
authors.lastname: Cheung
authors.forename: P T
authors.initials: PT
authors.lastname: Choi
authors.forename: K S
authors.initials: KS
authors.lastname: Wong
mesh_terms: D000328:Adult; D004569:Electroencephalography / Q000379:methods*; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012640:Seizures / Q000517:prevention & control; D015899:Tomography, Emission-Computed, Single-Photon