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Frontal lobe epilepsy manifesting with seizures consisting of isolated vocalization Volume 8, numéro 4, December 2006

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  • Frontal Lobe epilepsy manifesting with seizure consisting of isolated vocalization

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Auteur(s) : Ricardo Rego1, Stephan Arnold2, Soheyl Noachtar2

1Neurology Service, Hospital Pedro Hispano, Matosinhos, Portugal
2Dept. of Neurology, University of Munich, München, Germany

Article reçu le 22 Février 2006, accepté le 2 Septembre 2006

The 52-year-old, right-handed male underwent video-EEG evaluation of paroxysmal episodes that had occurred several times a day since he was 14 years old. These episodes were characterized as an involuntary production of a “groaning” sound, which at times was preceded by a feeling of unspecific “inner tension” and “tingling” throughout his whole body. They had previously been attributed to “nervousness”, but after a diagnosis of epilepsy was suggested in recent years, the patient received anti-epileptic treatment. The patient’s prior medical history included a possibly relevant, perinatal hypoxia. Neurological examination disclosed no abnormalities. The patient had previously undergone a high-resolution brain MRI (1.5 Tesla, 2 mm slices) including T1-3D, T2 and FLAIR sequences, with normal results.Video-EEG monitoring was performed after the withdrawal of anti-epileptic drugs (carbamazepine, sodium valproate, gabapentin, and levetiracetam). Interictal recordings showed a normal background rhythm with intermittent generalized slow activity; no interictal epileptiform discharges were recorded. Four identical seizures, recorded during one night, occurred during stage I sleep. They consisted of an arousal, followed by a monotonous vocalization lasting four to seven seconds (see video sequence). Upon testing, the patient was fully responsive. He reported having had his usual aura (diffuse “inner tingling”) immediately before the vocalization. A seizure pattern (fast rhythmical activity) was consistently recorded over the left frontal region, starting two to four seconds before the vocalization and lasting three to five seconds ( (figure 1) ).Further investigations, such as invasive EEG or functional imaging, were not performed since epilepsy surgery was not contemplated (seizure control was satisfactory under medical treatment).

Discussion

Pure ictal vocalizations have been recently defined as audible sounds that lack speech quality and do not accompany apnea or clonic or generalized tonic-clonic seizures (Janszky et al. 2000). In a review of 27 patients with frontal lobe epilepsy, confirmed by pre-surgical evaluation and seizure-freedom after frontal lobe resections, ictal vocalizations occurred during different seizure types (more frequently tonic) in 11 patients. Those patients with left-sided frontal foci, as the ictal EEG suggests in our case, had ictal vocalizations significantly more often than patients with right-sided foci (75% versus 13%). Another report on a series of frontal lobe epilepsy patients, who underwent resective epilepsy surgery (Laskowitz et al. 1995), noted ictal vocalizations (less stringently defined as a “phonation of any kind”) during the seizures of approximately two-thirds of the patients; however, an association between vocalization and lateralization was not found.

In a study of the different speech manifestations during seizures that arise from temporal regions, Gabr et al. (1989) observed ictal vocalizations, defined as sustained or interrupted sounds with no speech quality, during the seizures of almost half of the patients. There was a non-statistically significant trend toward seizures originating in the dominant temporal lobe. Ictal speech however, and positictal aphasia showed a significant association with seizure-onset in the non-dominant and dominant hemisphere, respectively (Gabr et al. 1989).

Although the gold standard for focal epilepsy classification is post-surgical seizure-freedom after a focal resection, we feel that a diagnosis of frontal lobe epilepsy in our patient is supported by the clear left frontal ictal EEG and by the clinical features. He had clusters of brief seizures arising from sleep, with preserved responsiveness, as is frequently seen in frontal lobe epilepsies; furthermore, auras with a diffuse “tingling” or “tension” sensation and tonic vocalizations are common during the early phase of seizures originating or spreading to the supplementary sensorimotor area, which may then evolve rapidly into a bilateral asymmetric tonic seizure (Kellinghaus and Lüders, 2004).

In our patient, ictal vocalizations repeatedly occurred as the single objective manifestation of epileptic seizures arising from the left frontal lobe. To the best of our knowledge a similar finding has not yet been reported.

Acknowledgements

The authors wish to thank the EEG-technicians of the Epilepsy Monitoring Unit of the University of Munich hospital for their skill and support as well as Mrs. Judy Benson for copy editing the manuscript.