The ILAE definition of drug resistant epilepsy and its clinical applicability compared with “older” established definitions


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Journal of Epileptology

Foundation of Epileptology

Subject: Medicine


eISSN: 2300-0147





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VOLUME 23 , ISSUE 1 (June 2015) > List of articles

The ILAE definition of drug resistant epilepsy and its clinical applicability compared with “older” established definitions

Alexandra Rohracher / Judith Dobesberger / Claudia A. Granbichler / Julia Höfler / Giorgi Kuchukhidze / Martin Ortler / Iris Unterberger / Gerald Walser / Aljoscha Thomschewski / Eugen Trinka *

Keywords : definitions of drug resistant epilepsy, epilepsy surgery

Citation Information : Journal of Epileptology. Volume 23, Issue 1, Pages 39-44, DOI:

License : (CC BY 4.0)

Received Date : 25-January-2015 / Accepted: 19-March-2015 / Published Online: 02-April-2015

Open Access article funded by Alexandra Rohracher received travel support from Eisai. Claudia A. Granbichler received travel suppo



Background. Early identification of potential epilepsy surgery candidates is essential to the treatment process.

Aim. To evaluate the clinical applicability of the ILAE definition of drug resistant epilepsy and its potential in identifying surgical candidates earlier compared to three established “older” definitions of drug resistant epilepsy.

Material and methods. Retrospective analysis of 174 patients who underwent epilepsy surgery between 1998 and 2009. Clinical factors and course of disease were extracted from patients' charts. Drug resistant epilepsy was classified according to four definitions and the time until fulfillment of criteria compared.

Results. Mean time to fulfillment of criteria of drug resistant epilepsy ranged from 11.8 (standard deviation (SD) 9.8) to 15.6 years (SD 11.3). Time to drug resistance was significantly longer applying the only definition, requiring failure of three antiepileptic drugs (AEDs) (Canada definition), whereas time to fulfillment of all other definitions did not differ. Fifty percent of all patients experienced a seizure free period of _1 year prior to being classified as drug resistant, 13% entered another 1-year remission after fulfilling any criteria for drug resistance.

Conclusion. We conclude that the ILAE definition identifies drug resistant epilepsy, with similar latency like two of three formerly used definitions. It is an easy applicable tool to minimize the delay of referral to a specialized center. Intermittent remissions delay assessment of drug resistance for all definitions and 13% of patients enter a remission despite established drug resistance.

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