title: Timing of early and late seizure recurrence after temporal lobe epilepsy surgery.
abstract: OBJECTIVE
  Seizure recurrence after epilepsy surgery has been classified as either early or late depending on the recurrence time after operation. However, time of recurrence is variable and has been arbitrarily defined in the literature. We established a mathematical model for discriminating patients with early or late seizure recurrence, and examined differences between these two groups.
  
  
  METHODS
  A historical cohort of 247 consecutive patients treated surgically for temporal lobe epilepsy was identified. In patients who recurred, postoperative time until seizure recurrence was examined using an receiver-operating characteristic (ROC) curve to determine the best cutoff for predicting long-term prognosis, dividing patients in those with early and those with late seizure recurrence. We then compared the groups in terms of a number of clinical, electrophysiologic, and radiologic variables.
  
  
  RESULTS
  Seizures recurred in 107 patients (48.9%). The ROC curve demonstrated that 6 months was the ideal time for predicting long-term surgical outcome with best accuracy, (area under the curve [AUC] = 0.761; sensitivity = 78.8%; specificity = 72.1%). We observed that patients with seizure recurrence during the first 6 months started having seizures at younger age (odds ratio [OR] = 6.03; 95% confidence interval [CI] = 1.06-11.01; p = 0.018), had a worse outcome (OR = 6.85; 95% CI = 2.54-18.52; p = 0.001), needed a higher number of antiepileptic medications (OR = 2.07; 95% CI = 1.16-9.34; p = 0.013), and more frequently had repeat surgery (OR = 9.59; 95% CI = 1.18-77.88; p = 0.021). Patients with late relapse more frequently had seizures associated with trigger events (OR = 9.61; 95% CI = 3.52-26.31; p < 0.01).
  
  
  CONCLUSIONS
  Patients with early or late recurrence of seizures have different characteristics that might reflect diversity in the epileptogenic zone and epileptogenicity itself. These disparities might help explain variable patterns of seizure recurrence after epilepsy surgery.
authors.affiliation: Epilepsy Program, Department of Clinical Neurological Sciences, Western University, London Health Sciences Centre, London, Ontario, Canada; Hospital Mãe de Deus, Porto Alegre, Rio Grande do Sul, Brazil; Postgraduate Program in Medical Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Goellner
authors.forename: Marino M
authors.initials: MM
authors.lastname: Bianchin
authors.forename: Jorge G
authors.initials: JG
authors.lastname: Burneo
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Parrent
authors.forename: David A
authors.initials: DA
authors.lastname: Steven
mesh_terms: D000927:Anticonvulsants / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000188:drug therapy / Q000601:surgery*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011184:Postoperative Period; D055502:Secondary Prevention; D012640:Seizures / Q000188:drug therapy; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000927:Anticonvulsants
keywords: Epilepsy surgery; Recurrence; Temporal lobe epilepsy; Timing