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

Abstract

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.

Ictal Blinking in Hepatic Encephalopathy Pre- and Post-Liver Transplant: Report of Eight Patients

“…In this series IB constituted 2.2% of focal seizures. 9 In our patients IB was approximately 4.4% of all seizure cases. All eight patients except case 7 in this report had a routine 20 minutes EEG after 1 to 4 hours after noting IB.…”

“…The most recent publication on IB reported unilateral eye blinking was more useful localizing sign as compared with bilateral blinking which had no localizing value. 9 In unilateral blinking the localization was mostly in opposite frontotemporal region on EEG. In this series IB constituted 2.2% of focal seizures.…”

“…Poor localizing value of EEG abnormality in IB has already been reported previously, and this was also seen in our series. 2,[7][8][9][10]12 Tacrolimus is used in liver transplant patients as immunosuppressant to guard against rejection of the transplanted liver. 16 Tacrolimus has known neurotoxicity and known precipitant of seizures.…”

“…When it is unilateral blinking it is more specific lateralizing sign of partial seizures. 7 8 9 Isolated or pure blinking has been described in two children. 8 10 However, in one study of 61 adults with EM, the authors divided them into three groups based on history, seizure semiology, and EEG findings.…”

“…Poor localizing value of EEG abnormality in IB has already been reported previously, and this was also seen in our series. 2 7 8 9 10 12…”