Understanding of Rapid Ictal Blinking: Definition Criteria, Prevalence, and Localizing Value

Ictal blinking is an undefined phenomenon of involuntary bilateral blinks during a seizure, at a higher frequency than baseline blinking that is not associated with other facial motor manifestations. In most reports, the epileptogenic zone has been identified in the occipital regions. The purpose of this study is to characterize ictal blinking and assess its potential localizing value.

EEG and EOG data from 45 patients with seizures from temporal, occipito-parietal, and fronto-central regions (15 per group) were analyzed. Blinks were quantified in 15-second epochs during ictal and baseline phases. Baseline duration matched the ictal phase or extended to 150 seconds. RIB is defined as the blinking rate at least 50% greater than the average baseline blinking during any ictal window. The ictal blinking rate ratio (BRR) was also calculated for each group, defined as the ratio of maximum ictal blinks to average baseline blinks. Ictal blink suppression (BS) was defined as no blinks in the first 30 seconds of a seizure.

The average blinking frequency during the baseline period was four blinks every 15-second page. The average ictal blinks for patients who met the criteria for RIB were seven per 15-second page. RIB occurs most frequently in temporal epilepsy (73%) and less commonly in frontal epilepsy (47%). Ictal BRR is highest (5.6) in occipital epilepsy. Ictal BS occurred in 22% of cohort.

RIB is a frequent ictal phenomenon without significant localizing value. Ictal BRR was significantly higher for patients with occipital seizures. Based on the findings, a practical definition for RIB was proposed: seven or more blinks in any 15-second epoch during seizure.