A classification system for verifying the long-term efficacy of resective surgery for drug-resistant seizures

• Published in: Epilepsy research 2018-03, Vol.141, p.23-30
• Main Authors: Mihara, Tadahiro, Usui, Naotaka, Matsuda, Kazumi, Tottori, Takayasu, Kondo, Akihiko, Terada, Kiyohito, Inoue, Yushi
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; AED (antiepileptic drug) withdrawal; Anticonvulsants - adverse effects; Child; Child, Preschool; Classification - methods; Cohort Studies; Disability Evaluation; Drug Resistant Epilepsy - surgery; Electroencephalography; Epilepsy surgery; Female; Humans; Infant; Late recurrence; Male; Middle Aged; Neurosurgery - methods; Outcome Assessment (Health Care) - classification; Outcome Assessment (Health Care) - methods; Running-down phenomenon; Seizure outcome classification; Treatment Outcome; Young Adult
• ISSN: 0920-1211; 1872-6844
• DOI: 10.1016/j.eplepsyres.2018.01.019

•To verify long-term efficacy of epilepsy surgery, we created a classification system.•The system’s basic components were patterns of postoperative seizure emergence.•We analyzed postoperative seizures in 646 patients with 8+ years of follow-up.•The results confirmed the validity and usefulness of our classification system.•Our system clarifies effectiveness of surgery more precisely than the Engel scale. To verify the long-term efficacy of resective surgery, we created a classification system in which strictly defined patterns of postoperative seizure emergence are incorporated as basic components and the seizure states throughout the entire follow-up period are assessed comprehensively. In our system, Class I has three subclasses (A–C); subclasses A and B are identical to Engel I-A and I-B, respectively. Subclass C comprises patients whose disabling seizures remit within the first 2 years postoperatively. Patients in Class II have only 1–3 days with disabling seizures throughout follow-up after the first 2 years. Patients in Class III have a maximum of 3 seizure days annually, and those in Class IV have ≥4 seizure days annually after the first 2 years. Classes II–IV each have 2 subclasses (A and B): subclass A, late recurrence (i.e., the first seizure occurs after 2 years postoperatively); and subclass B, early recurrence (i.e., first seizure within 2 years). In 646 patients who underwent resective surgery (temporal lobe resection, 74.6%) and were followed for at least 8 years (mean, 14.6 years), we analyzed three patterns of postoperative seizures: early remission, late recurrence, and occasional seizures. In addition, we investigated the differences between the long-term seizure outcomes of the cohort as determined according to our system and the Engel scale. Overall, 52.9% of the cohort experienced at least one disabling seizure postoperatively throughout the follow-up period; in 1/3 of these patients, the first seizure occurred after 2 years. In 73.8% of the 80 patients who manifested the running-down phenomenon, seizure remission occurred within the first 2 years. In addition, 36.7% of the 283 patients who had disabling seizures after 2 years experienced only 1–3 seizure days. Engel Class I-C included about 30% of the patients who had ≥4 seizure days after 2 years. The long-term seizure outcomes, determined according to our system, were: Class I, 56.2% (C, 9.1%) of the overall cohort; Class II, 16.1% (A, 11.0%); and Class III/IV, 27.7% (A, 6.6%). Ou