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Epilepsy Surgery Candidacy: Comprehensive Presurgical Evaluation Framework

Epilepsy surgery offers seizure freedom for carefully selected patients with drug-resistant focal epilepsy. Candidacy determination requires a structured, multidisciplinary evaluation.

Inclusion Criteria (All Required)

  1. Drug-Resistant Epilepsy (DRE): Failure of ≥2 appropriately chosen, tolerated AEDs (mono- or polytherapy) to achieve sustained seizure freedom (ILAE definition).
  2. Focal Epilepsy: Seizures arise from a discrete, identifiable network (not generalized).
  3. Concordant Localization: Non-invasive data converge on a single resectable zone.
  4. Resectable Eloquence: Seizure focus can be removed/disconnected without unacceptable neurologic deficit (language, motor, vision, memory).
  5. Favorable Risk-Benefit: Probability of seizure freedom > risk of permanent deficit.

Phase 1: Non-Invasive Evaluation

ModalityPurpose
3T MRI (Epilepsy Protocol)Structural lesion: HS, FCD, tumor, cavernoma, encephalomalacia
Video-EEG Monitoring (EMU)Capture habitual seizures; ictal onset localization; semiology
Neuropsychological TestingBaseline cognition, memory, language lateralization (Wada/fMRI alternative)
FDG-PET (Interictal)Hypometabolism in seizure focus (esp. if MRI-negative)
SPECT (Ictal > Interictal)Hyperperfusion at onset zone
MEG (Magnetoencephalography)Non-invasive dipole modeling of interictal spikes

Phase 2: Invasive Monitoring (If Phase 1 Discordant or Eloquent Cortex)

  • Stereo-EEG (SEEG): Depth electrodes; minimal morbidity; 3D sampling; preferred.
  • Subdural Grids/Strips: Surface coverage; cortical mapping; higher infection risk.
  • Goal: Define epileptogenic zone (EZ) vs. irritative zone; functional mapping (stimulation).

Surgical Options

  • Resective: ATL (anterior temporal lobectomy), lesionectomy, multilobar, hemispherotomy.
  • Disconnective: Corpus callosotomy (drop attacks), multiple subpial transections.
  • Neuromodulation (if not resectable): RNS (responsive neurostimulation), DBS (anterior nucleus), VNS.

Outcome Metrics

  • Engel Class I (seizure-free): 60–70% for temporal lobe; 40–50% extratemporal.
  • Complication rate: ~3–5% permanent deficit (visual field, memory, language).
  • Mortality: <0.5%.

Multidisciplinary Team (MDT) Conference

Neurologists, neurosurgeons, neuropsychologists, neuroradiologists, nurses, social workers review all data → consensus recommendation → informed consent with patient/family.

Surgery is not a last resort—it's a targeted therapy for the right patient at the right time. Early referral for DRE improves lifelong outcomes.

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