Unilateral Blinking: Insights from Stereo-EEG and Tractography

Abstract

To study the neuroanatomical correlate of involuntary unilateral blinking in humans, using the example of patients with focal epilepsy. Patients with drug resistant focal epilepsy undergoing presurgical evaluation with stereotactically implanted EEG-electrodes (sEEG) were recruited from the local epilepsy monitoring unit. Only patients showing ictal unilateral blinking or unilateral blinking elicited by direct electrical stimulation were included (n = 16). MRI and CT data were used for visualization of the electrode positions. In two patients, probabilistic tractography with seeding from the respective electrodes was additionally performed. Three main findings were made: (1) involuntary unilateral blinking was associated with activation of the anterior temporal region, (2) tractography showed widespread projections to the ipsilateral frontal, pericentral, occipital, limbic and cerebellar regions and (3) blinking was observed predominantly in female patients with temporal lobe epilepsies. Unilateral blinking was found to be associated with an ipsilateral activation of the anterior temporal region. We suggest that the identified network is not part of the primary blinking control but might have modulating influence on ipsilateral blinking by integrating contextual information.

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

“…However, in this report, ictal phenomena of patients were not defined for previous seizures. 22 In one of our patients with asymmetrical blinking, a fast ictal rhythmic activity, recorded by a scalp EEG, raised from ipsilateral occipital region to the predominant blinking side. This ictal EEG pattern was first described by Saporito et al in 2017 and we could also confirm their hypothesis that epileptic discharges with an EEG pattern of a rapid ictal activity arising from occipital areas may lead to ictal blinking.…”