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Prevalence of Nonlesional Focal Epilepsy in an Adult Epilepsy Clinic

  • Dang Khoa Nguyen (a1), Manuela Temgoua Mbacfou (a2), Dong Bach Nguyen (a1) and Maryse Lassonde (a3)

Abstract

Purpose:

To evaluate the prevalence of nonlesional focal epilepsy in an adult epilepsy clinic and its refractoriness to antiepileptic drug therapy.

Background:

Focal epilepsy is frequently, but not always, associated with structural epileptogenic lesions identifiable on magnetic resonance imaging (MRI).

Methods:

We analyzed the data from all patients evaluated at an adult epilepsy clinic from January 2002 to December 2011. Clinical and paraclinical findings were used to diagnose focal epilepsy. Magnetic resonance imaging were reviewed and classified as normal, with an epileptogenic lesion, or with a lesion of unclear epileptogenicity. Epileptogenic lesions were further categorized as tumours, vascular malformations, gliosis (including hippocampal atrophy/sclerosis), and malformations of cortical development. Our study group included patients with no lesions on MRI. Pharmacoresistance of patients with nonlesional focal epilepsy was assessed using the ILAE and Perucca's criterias.

Results:

Out of 1521 patients evaluated (mean age 44 years; range 14-93 years), 843 had focal epilepsy. Magnetic resonance imaging data, available for 806 (96%) subjects, showed epileptogenic lesions in 65%, no obvious epileptogenic lesions in 31% and lesions of unclear epileptogenicity in 4%. Magnetic resonance imaging-identified lesions included gliosis due to an acquired insult (52% including 17% of hippocampal atrophy or sclerosis), tumours (29%), vascular malformations (16%) and malformations of cortical development (10%). Fifty-two percent of nonlesional focal epileptic patients were drug-refractory.

Conclusion:

In a tertiary epilepsy clinic, close to a third of patients with focal epilepsy were found to be nonlesional, half of which were drug-resistant.

Résumé: Objectif:

Le but de l'étude était d'évaluer la prévalence de l'épilepsie focale non-lésionnelle dans une clinique d'épilepsie pour adultes et sa résistance au traitement par la médication antiépileptique.

Contexte:

L'épilepsie focale est souvent, mais pas toujours, associée à des lésions épileptogènes structurales identifiables à l'imagerie par résonance magnétique (IRM).

Méthode:

Nous avons analysé les données des dossiers de tous les patients évalués à une clinique d'épilepsie pour adultes de janvier 2002 à décembre 2011. Les observations cliniques et paracliniques ont été utilisées pour poser un diagnostic d'épilepsie focale. Nous avons révisé les observations d'IRM et nous les avons classifiées comme étant normales, mettant en évidence une lésion épileptogène ou démontrant une lésion dont l'épileptogénicité n'était pas claire. Les lésions épileptogènes étaient ensuite catégorisées comme étant des tumeurs, des malformations vasculaires, de la gliose (incluant l'atrophie ou la sclérose de l'hippocampe) et des malformations du développement cortical. Notre échantillon de patients comprenait des patients sans lésion à l'IRM. La pharmacorésistance des patients atteints d'une épilepsie focale sans lésion a été évaluée au moyen des critères de l'ILAE et de Perucca.

Résultats:

Parmi les 1 521 patients évalués, qui étaient âgés de 14 à 93 ans et dont l'âge moyen était de 44 ans, 843 avaient une épilepsie focale. Les données d'IRM, qui étaient disponibles pour 806 patients (96%), avaient démontré des lésions épileptogènes chez 65%, pas de lésion épileptogène évidente chez 31% et des lésions dont l'épileptogénicité était douteuse chez 4%. Les lésions identifiées à l'IRM étaient de la gliose due à une lésion acquise (52%, dont 17% d'atrophie ou de sclérose hippocampique), des tumeurs (29%), des malformations vasculaires (16%) et des malformations du développement cortical (10%). Cinquante-deux pour cent des patients atteints d'une épilepsie focale non reliée à une lésion étaient résistants au traitement pharmacologique.

Conclusion:

Dans une clinique de soins tertiaires de l'épilepsie, l'épilepsie n'était pas reliée à une lésion chez près du tiers des patients atteints d'une épilepsie focale et la moitié d'entre eux étaient pharmacorésistants.

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Copyright

Corresponding author

Service de Neurologie, Hôpital Notre-Dame du CHUM, 1560 rue Sherbrooke Est, Montréal, Québec, H2L 4M1, Canada. Email: d.nguyen@umontreal.ca.

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Prevalence of Nonlesional Focal Epilepsy in an Adult Epilepsy Clinic

  • Dang Khoa Nguyen (a1), Manuela Temgoua Mbacfou (a2), Dong Bach Nguyen (a1) and Maryse Lassonde (a3)

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