Elsevier

Epilepsy Research

Volume 125, September 2016, Pages 58-61
Epilepsy Research

Short communication
Ictal unilateral blinking is an unreliable lateralizing sign in tuberous sclerosis complex

https://doi.org/10.1016/j.eplepsyres.2016.06.006Get rights and content

Highlights

  • Unilateral blinking during focal seizures suggests an ipsilateral focus.

  • Unilateral blinking is not uncommon in focal seizures in children with TSC.

  • In TSC, ictal unilateral blinking may be ipsilateral or contralateral to the focus.

  • In TSC, unilateral blinking early in seizures is more often contralateral.

  • Seizure propagation and different mechanisms may cause the variable lateralization.

Abstract

Objective

Ictal unilateral blinking is an uncommon but reportedly reliable lateralizing sign, indicating an ipsilateral seizure focus. We aimed to determine its lateralizing utility in patients with tuberous sclerosis complex (TSC).

Methods

We reviewed the video-EEGs of 92 children with TSC and drug-resistant epilepsy. Eleven (12%) had seizures with unilateral blinking, of which 10 underwent epilepsy surgery. Lateralization of seizures was inferred from other semiology, ictal scalp EEG and outcome following tuberectomy.

Results

Seizures manifesting with unilateral blinking were focal motor in four patients, focal motor evolving into epileptic spasms in six, and epileptic spasms with focal features in one. Associated unilateral facial contraction was seen in five patients and arm jerking in four. Lateralized scalp ictal rhythms were seen in seven patients. Following tuberectomies, seven patients are seizure free and two had >90% reduction. Overall lateralization of seizures with unilateral blinking was contralateral in six patients and ipsilateral in four. When unilateral blinking was early in seizures, overall lateralization was more often contralateral (6/7 patients, PPV 85%).

Significance

Ictal unilateral blinking is not infrequent but unreliable in lateralizing seizures in TSC. Unrecognized seizure propagation to contralateral symptomatogenic regions and potentially different mechanisms may account for the variable lateralization.

Introduction

Ictal unilateral blinking is an uncommon but reportedly reliable sign, indicating an ipsilateral focus (Benbadis et al., 1996). Having observed unilateral blinking often during seizures in children with tuberous sclerosis complex (TSC), we sought to determine its utility in TSC.

Section snippets

Methods

We reviewed the clinical, EEG, MRI and surgical data in children with TSC and drug-resistant epilepsy evaluated at our center between 1997 and 2013. Videos of patients whose video-EEG monitoring (VEM) reported ‘blinking’, ‘eyelid/eye blinks’ or ‘eyelid twitching’ were reviewed, blind to localization of their EEG, tubers and surgery. Only patients with clear ictal unilateral blinking were included. Other focal motor semiology, ictal scalp EEG and post-operative seizure outcome were used to infer

Results

Ictal blinking was reported in 20/92 TSC patients who underwent VEM. Eleven (12%) had clear unilateral ictal blinking, of whom 10 underwent tuberectomy and are the basis of this report.

The 10 patients (6 males) were aged 1.9–18 years (mean 10) during VEM. All had multiple bilateral tubers. Findings from VEM and surgery are summarized in Table 1.

Discussion

The frequency of ictal unilateral blinking in our TSC series was 12%, greater than the 1.5% reported in patients with focal epilepsy due to vascular malformations, neoplasms and heterotopias (Benbadis et al., 1996). Unilateral blinking seizures are reported to be mainly of temporal or frontal origin (Kalss et al., 2013, Pestana and Gupta, 2007, Henkel et al., 1999, Benbadis et al., 1996, Wada, 1980), as seemed to be the case in our series.

Wada originally reported unilateral blinking to be

Acknowledgement

None.

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Cited by (7)

  • Ictal blinking in focal seizures: Insights from SEEG recordings

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    The prevalence of bilateral ictal blinking in our population of SEEG-investigated patients was approximately 7% with an over-representation in occipital SOZ (prevalence of 57.1%) which is in accordance with existing literature on occipital epilepsy (prevalence ranging from 15 to 62.5%) [7,23–27]. The prevalence of unilateral ictal blinking in our cohort was approximately 1.3 %, that is consistent with previous studies (0.7-1,5%) [5,6,9], except in a series focusing on patients with tuberous sclerosis complex (12 %) [10]. Noteworthy, because we have excluded patients without optimal visualisation of both eyes, it is possible that we have a little underestimated the prevalence of ictal eye blinking in our cohort.

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