Ictal Blinking: Definition Criteria, Prevalence and Localizing Value
Saeideh Salehizadeh1, Suraj Thyagaraj1, Naiara Garcia Losarcos1, Hans Luders1
1Epilepsy Center, Neurological Institute, University Hospitals, Cleveland Medical Center
Objective:

We aim to establish definition criteria for Ictal blinking, estimate the prevalence of it in focal epilepsy and evaluate its localizing value.

Background:

Ictal Blinking (IB) is an undefined phenomenon in epilepsy that refers to the involuntary bilateral blinks during a seizure, at a higher frequency than the patient's baseline blinking, that is not associated with other facial motor manifestations. In most reports, the epileptogenic zone has been identified in the occipital or temporo-occipital regions.

Design/Methods:

We reviewed 45 patients with seizures originating from the temporal, occipito-parietal, and fronto-central regions (15 patients for each group) who underwent electroencephalography and electrooculography recordings. For each patient, we quantified the number of blinks per page (15-second windows) during the ictal phase and baseline as a control phase. For baseline measurements, the number of windows was chosen to achieve the same duration as ictal or 150 seconds, whichever was longer. We considered IB when the maximum ictal blinking was 1.5 times greater than the average baseline blinking in any window. We also calculated the ictal blinking ratio for each group (Maximum ictal blinking/average baseline blinking).

Results:
The overall average of baseline blinking (control period) was 4 blinks per page. The criteria for IB were met by 73% of patients with temporal seizures, while 60% of occipito-parietal and 47% of fronto-central seizures met the criteria. The ictal blinking ratio was estimated to be 5.6 for occipital epilepsy, 3.6 for temporal epilepsy patients, and 3.2 for fronto-central epilepsy.
Conclusions:

IB is a frequent phenomenon and does not seem to be associated with any specific epileptogenic zone. We hypothesize that a 1.5x increase in blinking during a seizure compared to baseline may help identify semiology as ictal blinking. Patients with occipital seizures who met the criteria for IB showed a significantly higher ictal blinking ratio, possibly provoked by a visual aura.

10.1212/WNL.0000000000205929