Premium
High‐frequency oscillations, extent of surgical resection, and surgical outcome in drug‐resistant focal epilepsy
Author(s) -
Haegelen Claire,
Perucca Piero,
Châtillon ClaudeEdouard,
AndradeValença Luciana,
Zelmann Rina,
Jacobs Julia,
Collins D. Louis,
Dubeau François,
Olivier André,
Gotman Jean
Publication year - 2013
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.12075
Subject(s) - epilepsy , ictal , stereoelectroencephalography , epilepsy surgery , temporal lobe , magnetic resonance imaging , medicine , anterior temporal lobectomy , cohort , electroencephalography , drug resistant epilepsy , surgery , radiology , psychiatry
Summary Purpose Removal of areas generating high‐frequency oscillations ( HFO s) recorded from the intracerebral electroencephalography ( iEEG ) of patients with medically intractable epilepsy has been found to be correlated with improved surgical outcome. However, whether differences exist according to the type of epilepsy is largely unknown. We performed a comparative assessment of the impact of removing HFO ‐generating tissue on surgical outcome between temporal lobe epilepsy ( TLE ) and extratemporal lobe epilepsy ( ETLE ). We also assessed the relationship between the extent of surgical resection and surgical outcome. Methods We studied 30 patients with drug‐resistant focal epilepsy, 21 with TLE and 9 with ETLE . Two thirds of the patients were included in a previous report and for these, clinical and imaging data were updated and follow‐up was extended. All patients underwent iEEG investigations (500 Hz high‐pass filter and 2,000 Hz sampling rate), surgical resection, and postoperative magnetic resonance imaging ( MRI ). HFO s (ripples, 80–250 Hz; fast ripples, >250 Hz) were identified visually on a 5–10 min interictal iEEG sample. HFO rates inside versus outside the seizure‐onset zone ( SOZ ), in resected versus nonresected tissue, and their association with surgical outcome ( ILAE classification) were assessed in the entire cohort, and in the TLE and ETLE subgroups. We also tested the correlation of resected brain hippocampal and amygdala volumes (as measured on postoperative MRI s) with surgical outcome. Key Findings HFO rates were significantly higher inside the SOZ than outside in the entire cohort and TLE subgroup, but not in the ETLE subgroup. In all groups, HFO rates did not differ significantly between resected and nonresected tissue. Surgical outcome was better when higher HFO rates were included in the surgical resection in the entire cohort and TLE subgroup, but not in the ETLE subgroup. Resected brain hippocampal and amygdala volumes were not correlated with surgical outcome. Significance In TLE , removal of HFO ‐generating areas may lead to improved surgical outcome. Less consistent findings emerge from ETLE , but these may be related to sample size limitations of this study. Size of resection, a factor that was ignored and that could have affected results of earlier studies did not influence results.