Unilateral blinking: a lateralizing sign in partial seizures.

BACKGROUND

Despite lateralizing signs, clinical lateralization of partial seizures may be difficult. We evaluated the usefulness of ictal unilateral blinking as a new lateralizing sign.

METHODS

We retrospectively searched our seizure database over a 30-month period and collected videotapes of patients with ictal unilateral blinking. After initial review, we excluded patients in whom blinking was not clearly unilateral and those in whom it was accompanied by simultaneous facial clonic activity or mouth deviation. All patients underwent prolonged EEG-video monitoring.

RESULTS

We identified 14 patients who met the above criteria, for a frequency of 1.5%. Age ranged from 18 months to 50 years (mean, 21.6). There were 11 males and 3 females. Unilateral blinking occurred 0 to 37 seconds (mean, 10) after clinical onset and was visible for 1 to 37 seconds (mean, 17). In 10 patients, other lateralizing signs were present. All patients had partial epilepsy, localized by surface EEG in 10 and by additional invasive EEG in four--nine were left hemisphere (four temporal, four frontal, one not further localized), three right hemisphere (two temporal, one frontal), and two undetermined. Of the 12 patients whose epileptogenic zone was lateralized, blinking was ipsilateral in 10 and contralateral in two. The predictive value of unilateral blinking was 83% against EEG localization.

CONCLUSION

Unilateral blinking is a relatively uncommon but reliable lateralizing sign in partial seizures, usually indicating an ipsilateral epileptogenic zone.