Optimal timing and differential significance of postoperative awake and sleep EEG to predict seizure outcome after temporal lobectomy Chaturbhuj Rathore a,⇑,1 , Pandurang R. Wattamwar a,2 , Neeraj Baheti a,3 , Malcolm Jeyaraj a,4 , Gopal K. Dash a,5 , Sankara P. Sarma b , Kurupath Radhakrishnan a,6 a R. Madhavan Nayar Center for Comprehensive Epilepsy Care, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India b Achutha Menon Center for Health Science Studies, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India article info Article history: Accepted 24 June 2018 Available online 30 June 2018 Keywords: Postoperative EEG Epilepsy surgery Temporal lobectomy Seizure outcome Antiepileptic drug withdrawal highlights  EEG done on 7th day following temporal lobectomy is not useful in predicting seizure outcome.  EEG at 3 months and 1 year following surgery has significant value in predicting seizure outcome.  Sleep recording improves the sensitivity of postoperative EEG by 30% without compromising specificity. abstract Objective: To evaluate the prognostic value of postoperative EEGs to estimate post anterior temporal lobectomy (ATL) seizure outcome. Methods: We studied postoperative EEGs in 325 consecutive patients who had minimum five years of post-ATL followup. Interictal epileptiform discharges (IEDs) present only during sleep were classified as sleep IEDs. We defined favorable final-year outcome as no seizures during the final one year and favor- able absolute-postoperative outcome as no seizures during the entire postoperative period. Results: At mean follow-up of 7.3 ± 1.8 years, 281 (86.5%) patients had favorable final-year outcome while 161 (49.5%) had favorable absolute-postoperative outcome. IEDs on three months and one year EEG were associated with unfavorable outcomes while IEDs at 7th day had no association with outcomes. Sleep record increased the yield of IEDs by 30% at each time-point without compromising predictive value. EEG at one year predicted the risk of seizure recurrence on drug withdrawal. Conclusion: While EEG at three months and at one-year after ATL predicted seizure outcome, EEG at 7th day was not helpful. Sleep record increases the sensitivity of postoperative EEG without compromising specificity. Significance: Both awake and sleep EEG provide useful information in postoperative period following ATL. Ó 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved. https://doi.org/10.1016/j.clinph.2018.06.014 1388-2457/Ó 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved. Abbreviations: AEDs, antiepileptic drugs; ATL, anterior temporal lobectomy; EEG, electroencephalogram; IED, interictal epileptiform discharges; MRI, magnetic resonance imaging; MTLE, mesial temporal lobe epilepsy; MTS, mesial temporal sclerosis; VEEG, video–electroencephalography. ⇑ Corresponding author at: Department of Neurology, Smt B K Shah Medical Institute and Research Center, Sumandeep Vidyapeeth, Piparia, Waghodiya, Vadodara 391760, Gujarat, India. Fax: +91 02668 245292. E-mail address: cbrathore@rediffmail.com (C. Rathore). 1 Present address: Department of Neurology, Smt B K Shah Medical Institute and Research Center, Sumandeep Vidyapeeth, Vadodara, Gujarat, India. 2 Present address: Department of Neurology, United CIIGMA Hospital, Aurangabad, Maharashtra, India. 3 Present address: Department of Neurology, Central India Institute of Medical Sciences, Nagpur, Maharashtra, India. 4 Present address: Department of Neurology, Stanley Medical College, Chennai, Tamil Nadu, India. 5 Present address: Department of Neurology, Narayana Hrudayalaya Hospital, Bengaluru, Karnataka, India. 6 Present address: Amrita Advanced Epilepsy Center, Department of Neurology, Amrita Institute of Medical Sciences, Kochi, Kerala, India. Clinical Neurophysiology 129 (2018) 1907–1912 Contents lists available at ScienceDirect Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph