Ictal blinking in focal seizures: Insights from SEEG recordings

Abstract

Purpose: Ictal blinking may be observed in various forms of epilepsies. In the context of presurgical assessment of drug-resistant focal epilepsies, its semiological value is poorly understood. Our aims were to determine the prevalence and localizing value of ictal blinking.

Methods: We reviewed our cohort of more than 300 patients explored by SEEG, searching for ictal blinking. We defined seizure onset zone (SOZ) using visual analysis complemented by a quantified method (epileptogenicity index). We analysed the features of ictal blinking and the associated signs. We tested for statistically significant associations with the underlying SOZ.

Results: We found that about 8% of our patients exhibited ictal blinking, mostly bilateral. Ictal blinking was seen mostly in four types of SOZ: occipital, occipito-temporal, temporal mesial, and insulo-opercular. It was significantly over-represented in occipito-temporal and occipital SOZ. Eye blinking was fastest in insulo-opercular SOZ and slowest in temporal mesial SOZ. Nystagmus and tonic eye deviation were associated with SOZ involving the occipital lobe.

Conclusion: Ictal blinking is not uncommon in the population of patients with drug-resistant focal epilepsies. It is mostly associated with four types of SOZ: occipital, occipito-temporal, temporal mesial, and insulo-opercular. Some features of ictal blinking, as well as the analysis of the associated signs, allow to orient clinical hypotheses toward some specific SOZ.

Keywords: Blinking; Drug-resistant epilepsy; Epilepsy surgery; Focal epilepsy; SEEG; Semiology.