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Long-term follow-up of a large cohort with focal epilepsy of unknown cause: deciphering their clinical and prognostic characteristics

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Abstract

Background and purpose

Focal epilepsy of unknown cause (FEUC) is an under-investigated topic despite its remarkable frequency. We aimed to report the long-term follow-up findings along with the drug-response, 5 year remission rates and diagnostic changes to give an insight about the heterogeneous characteristics of FEUC.

Methods

Demographic, clinical, neurophysiological and imaging data of 196 patients diagnosed as FEUC according to ILAE criteria, with a minimum 5-year follow-up were evaluated in a tertiary epilepsy center. The drug resistance, 5 years of remission and relapse rates were investigated and the subgroups were compared statistically.

Results

The rate of drug resistance was 21.8% and status epilepticus (p < 0.001), abnormal neurological examination (p = 0.020), seizure onset before 10 years (p = 0.004) and a high initial seizure frequency (p = 0.006) were significant predictors of drug resistance. The rates of terminal 5-year remission, 5-year remission ever and relapse were 39.9%, 44.26% and 24.04%, respectively. There were 13 patients (6.6%) with a changed final diagnosis. Drug resistance (p = 0.004), pathological EEG (p = 0.034) and status epilepticus (p = 0.021) were negative variables for achieving remission. The lobar localization of seizures was not a predictor of remission or relapse. Onset after 10 years of age had a higher probability of achieving a 5-year remission according to Kaplan–Meier curves (p < 0.001).

Conclusions

Focal epilepsy of unknown cause has a benign electroclinical subgroup with favorable long-term course, lower drug resistance and higher 5 years of terminal remission and remission ever rates, when appropriately treated. Our findings might be valuable in terms of counseling and management of patients with FEUC at the first referral to epilepsy clinics.

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Change history

  • 26 December 2019

    The original version of this article unfortunately contained a mistake.

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Funding

This study was supported by the Istanbul University Research Fund (Project No: BAP-2018-31114).

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Authors and Affiliations

  1. Department of Neurology, Istanbul Education and Research Hospital, Org. Nafiz Gürman St. Fatih, Istanbul, Turkey

    Arife Çimen Atalar

  2. Department of Neurology, Koc University Hospital, Istanbul, Turkey

    Ebru Nur Vanlı-Yavuz

  3. Department of Nuclear Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey

    Ebru Yılmaz

  4. Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey

    Nerses Bebek & Betül Baykan

  5. Department of Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey

    Betül Baykan

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  1. Arife Çimen Atalar
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Correspondence to Arife Çimen Atalar.

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Atalar, A.Ç., Vanlı-Yavuz, E.N., Yılmaz, E. et al. Long-term follow-up of a large cohort with focal epilepsy of unknown cause: deciphering their clinical and prognostic characteristics. J Neurol 267, 838–847 (2020). https://doi.org/10.1007/s00415-019-09656-8

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  • DOI: https://doi.org/10.1007/s00415-019-09656-8

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