Epilepsy Surgery Outcome Scales


The Engel Epilepsy Surgery Outcome Scale arose out of the 1992 Palm Desert Conference on Epilepsy Surgery and is widely used to classify outcome after surgical treatment for medically refractory outcome.

Engel Outcome Scale

Class I: Free of disabling seizures

  • IA: Completely seizure-free since surgery
  • IB: Non disabling simple partial seizures only since surgery
  • IC: Some disabling seizures after surgery, but free of disabline seizures for at least 2 years
  • ID: Generalized convulsions with antiepileptic drug withdrawal only

Class II: Rare disabling seizures (“almost seizure-free”)

  • IIA: Initially free of disabling seizures but has rare seizures now
  • IIB: Rare disabling seizures since surgery
  • IIC: More than rare disabling seiuzres after surgery, but rare seizures for at least 2 years
  • IID: Nocturnal seizures only

Class III: Worthwhile improvement

  • IIIA: Worthwhile seiuzre reduction
  • IIIB: Prolonged seiuzre-free intervals amounting to greater than half the follow-up period, but not less than 2 years
  • Class IV: No worthwhile improvement
    • IVA: Significant seizure reduction
    • IVB: No appreciable change
    • IVC: Seizures worse
  • From: Surgical Treatment of Epilepsies, 2nd Edition. Engel J., Editor. Raven Press, 1993. Page 615.

ILAE Outcome Scale

  • Class 1: Completely seizure free; no auras
  • Class 2: Only auras; no other seizures
  • Class 3: 1 to 3 seizure days per year; ± auras
  • Class 4: 4 seizure days per year to 50% reduction of baseline seizure days; ± auras
  • Class 5: Less than 50% reduction of baseline seizure days; ± auras
  • Class 6: More than 100% increase of baseline seizure days; ± auras