John Libbey Eurotext

Ipsilateral blinking: a rare lateralizing seizure phenomenon in temporal lobe epilepsy Volume 1, numéro 3, Septembre 1999

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  • Ipsilateral blinking: a rare lateralizing seizure phenomenon in temporal lobe epilepsy

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Several ictal lateralizing motor phenomena such as forced head and eye version [1], unilateral dystonic hand posturing [2], unilateral clonic seizures [3], and unilateral tonic seizures [4] occur contralateral to the seizure onset zone. Conversely, unilateral blinking has been described as a rare ipsilateral ictal phenomenon [5]. We reviewed the database of our epilepsy monitoring unit for ictal unilateral blinking and identified two patients. We report on these two patients, both of whom had temporal lobe epilepsy.

Methods

We reviewed the database of 239 consecutive patients with focal epilepsies who had been considered for epilepsy surgery. Unilateral blinking was defined as blinking of one eyelid which precedes eventual ipsilateral facial clonic activity or mouth deviation. All patients underwent prolonged, non-invasive EEG-video-monitoring and high resolution magnetic resonance imaging (MRI). In addition, 85% (n = 203) had interictal FDG-PET ([18F] fluoro-2-deoxy-d-glucose positron emission tomography) and 60% (n = 143) had ictal ECD-SPECT (99mTc-ethyl-cysteinate-dimer single photon emission computerized tomography). All ictal and interictal EEG and the seizures were classified at the time of the evaluation and entered into a database.

Results

The clinical data and the results of the investigations are summarized in table I. The seizure semiology of patient 1 consisted of abdominal auras which were followed by oral and manual automatisms and, eventually, generalized tonic-clonic seizures. Unilateral blinking occurred isolated, or followed abdominal auras and/or automotor seizures. The patient was conscious and able to describe unilateral blinking. The video shows isolated unilateral blinking of the right eye followed by ipsilateral facial cloni prompting the patient to press the seizure button. Patient 2 had seizures characterized by loss of consciousness and automatisms, which developed into generalized tonic-clonic seizures. The video demonstrates unresponsiveness to requests, as well as oral automatisms during blinking of the right eye. The patient was amnesic as regards his seizures.

In both patients, unilateral blinking was observed in all seizures, which could be adequately assessed on the video. Ictal EEG showed right temporal seizure patterns in all seizures of both patients (figure 1). Blinking started with a latency of 0-44 seconds (mean 13 sec) after clinical seizure onset, and 3-51 sec (mean 22 sec) after EEG onset. Mean duration of blinking was 12 sec (3-17 sec). No other lateralizing seizure phenomena were recorded in the patients.

Discussion

We found unilateral blinking as a rare ictal phenomenon in 2 (0.8%) of 239 patients, in whom EEG-video-monitoring was performed. The frequency in our series is similar to the frequency of 1.5% (14 of 914 patients) reported in the study of Benbadis et al. [5]. Contrary to the description of Benbadis et al. [5], eye blinking was more clonic than "wink-like" and eventually followed by twitching of the face or platysma in our patients. We did not find a preponderance for the left side.

Unilateral blinking was ipsilateral to the seizure focus in both of our patients. Benbadis et al. [5] calculated a positive predictive value (ppv) of 80% (4 of 5 patients) for an ipsilateral seizure onset in patients, in whom the seizure focus could be confirmed by surgery. Wada [6] described unilateral blinking ipsilateral to the ictal seizure activity in all 5 patients examined.

Unilateral blinking occurs in different focal epilepsy syndromes. Wada [6] described ipsilateral blinking exclusively during temporal seizure activity. Half of the patients of Benbadis et al. [5] had extratemporal epilepsies. Our two patients had temporal lobe epilepsy.

The symptomatogenic zone generating ipsilateral blinking is still unclear. It is well known, that the upper part of the facial motricity depends on both contralateral and ipsilateral motor cortical control mainly originating from the lower precentral gyrus [7]. Our observation of facial twitching following eyeblinking suggests the involvement of the precentral gyrus. On the other hand, lesions of the lower postcentral region resulted in abnormal ipsilateral corneal reflex latencies, so that this area was thought to have facilitating influences on the ipsilateral blinking reflex [8]. Lesser et al. [9] reported on the occasional presence of ipsilateral motor responses during stimulation by subdural electrodes and speculated, that the ipsilateral motor response is due to electrical activation of pial fibers to the facial nucleus or trigeminal-facial connections in the brainstem. Similarly, stimulation of the "second sensory area" can provoke ipsilateral sensations [7].

CONCLUSION

Unilateral blinking is a rare, but reliably lateralizing ipsilateral ictal phenomenon that occurs in temporal and extratemporal epilepsies. It is probably underappreciated because the patients may not be able to report it and because it is often not easily observed with the aid of the video technique.

Acknowledgements:

We are grateful to Mrs. R. Grossmann, E. Scherbaum, B. Schüssler, E. Sincini, S. Weiser and Mr O. Klein for excellent technical assistance in the EEG-video-monitoring and to Mrs. J. Benson for copy-editing the manuscript.