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

  • Arife Çimen AtalarEmail author
  • Ebru Nur Vanlı-Yavuz
  • Ebru Yılmaz
  • Nerses Bebek
  • Betül Baykan
Original Communication


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.


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.


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).


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.


Focal epilepsy with unknown cause Prognosis Cryptogenic epilepsy Long-term follow-up MRI-negative epilepsy Focal epilepsy 



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

Compliance with ethical standards

Conflicts of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Ethics approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of NeurologyIstanbul Education and Research HospitalIstanbulTurkey
  2. 2.Department of NeurologyKoc University HospitalIstanbulTurkey
  3. 3.Department of Nuclear Medicine, Istanbul Faculty of MedicineIstanbul UniversityIstanbulTurkey
  4. 4.Department of Neurology, Istanbul Faculty of MedicineIstanbul UniversityIstanbulTurkey
  5. 5.Department of Clinical Neurophysiology, Istanbul Faculty of MedicineIstanbul UniversityIstanbulTurkey

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