Ictal Blinking: Reappraisal of the Lateralization and Localization Value in Focal Seizures

Introduction. Although ictal blinking is significantly more frequent in generalized epilepsy, it has been reported as a rare but useful lateralizing sign in focal seizures when it is not associated with facial clonic twitching. This study aimed to raise awareness of eye blinking as a semiological lateralizing sign. Method. Our database over an 11-year period reviewed retrospectively to assess patients who had ictal blinking associated with focal seizures. Results. Among 632 patients, 14 (2.2%), who had 3 to 13 (7 ± 3) seizures during video-EEG monitoring, were included. Twenty-five percent of all 92 seizures displayed ictal blinking and each patient had one to five seizures with ictal blinking. Ictal blinking was unilateral in 17%, asymmetrical in 22% and symmetrical in 61%. The blinking appeared with a mean latency of 6.3 s (range 0-39) after the clinical seizure-onset, localized most often to fronto-temporal, then in frontal or occipital regions. Blinking was ipsilateral to ictal scalp EEG lateralization side in 83% (5/6) of the patients with unilateral/asymmetrical blinking. The exact lateralization and localization of ictal activity could not have been determined via EEG in most of the patients with symmetrical blinking, remarkably. Conclusions. Unilateral/asymmetrical blinking is one of the early components of the seizures and appears as a useful lateralizing sign, often associated with fronto-temporal seizure-onset. Symmetrical blinking, on the other hand, did not seem to be valuable in lateralization and localization of focal seizures. Future studies using invasive recordings and periocular electrodes are needed to evaluate the value of blinking in lateralization and localization.