Clinical Article

Acta Neurochirurgica

, Volume 153, Issue 2, pp 209-219

First online:

Randomized controlled trial of 2.5-cm versus 3.5-cm mesial temporal resection in temporal lobe epilepsy—part 1: intent-to-treat analysis

  • Johannes SchrammAffiliated withDepartment of Neurosurgery, University of Bonn Email author 
  • , T. N. LehmannAffiliated withDepartment of Neurosurgery, Campus Virchow Klinikum, Charité Berlin
  • , J. ZentnerAffiliated withDepartment of Neurosurgery, University of Freiburg
  • , C. A. MuellerAffiliated withDepartment of Neurosurgery, University of Bonn
  • , J. ScorzinAffiliated withDepartment of Neurosurgery, University of Bonn
  • , R. FimmersAffiliated withInstitute of Medical Biometrics, Informatics and Epidemiology, University of Bonn
  • , H. J. MeenckeAffiliated withDepartment of Epileptology, Epilepsiezentrum Berlin Brandenburg and von Bodelschwinghsche Anstalten, Königin Elisabeth Hospital Herzberge
  • , A. Schulze-BonhageAffiliated withEpilepsy Center, University Hospital of Freiburg
  • , C. E. ElgerAffiliated withDepartment of Epileptology, University of Bonn

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Only one prospective randomized study on the extent of mesial resection in surgery for temporal lobe epilepsy (TLE) exists. This randomized controlled trial (RCT) examines whether 3.5-cm mesial resection is leading to a better seizure outcome than a 2.5-cm resection.


Three epilepsy surgery centers using similar MRI protocols, neuropsychological tests, and resection types for TLE surgery included 207 patients in a RCT with pre- and postoperative volumetrics. One hundred and four patients were randomized into a 2.5-cm resection group and 103 patients into a 3.5-cm resection group, i.e., an intended minimum resection length of 25 versus 35 mm for the hippocampus and parahippocampus. Primary outcome measure was seizure freedom Engel class I throughout the first year. The study was powered to detect a 20% difference in class I outcome. Seizure outcome was available for 207 patients, complete volumetric results for 179 patients. Outcome analysis was restricted to control of successful randomization and an intent-to-treat analysis of seizure outcome.


The mean true resection volumes were significantly different for the 2.5-cm and 3.5-cm resection groups; thus, the randomization was successful. Median resection volume in the 2.5-cm group was 72.86% of initial volume and 83.44% in the 3.5-cm group. At 1 year, seizure outcome Engel class I was 74% in the 2.5-cm and 72.8% in the 3.5-cm resection group.


The primary intent-to-treat analysis did not show a different seizure freedom rate for the more posteriorly reaching 3.5-cm resection group. It appears possible that not maximal volume resection but adequate volume resection leads to good seizure freedom.


Temporal lobe epilepsy Epilepsy surgery Randomized controlled trial Amygdalohippocampectomy