Are ictal vocalisations related to the lateralisation of frontal lobe epilepsy?

The purpose was to analyse whether nonspeech vocalisations in seizures orig inating in the frontal lobe do have lateralising value. Patients were inclu ded who had undergone presurgical evaluation with ictal video-EEG monitorin g at the Epilepsy Centre, had had resective epilepsy surgery involving the frontal lobe, and who had remained seizure free>1 year postoperatively. Twe nty seven patients aged 1-42 years (mean 18) met the inclusion criteria. Ag e at epilepsy onset ranged from 1 month to 41 years (mean 7.1 years). All s elected patients had a unilateral MRI detected lesion within the frontal lo be. Fifteen patients had right sided, 12 patients had left sided epileptoge nic zones. Seizures recorded during EEG-video monitoring were re-evaluated to identify the occurrence of ictal vocalisations. Pure ictal vocalisations were distinguished from ictal sound productions due to motor or vegetative seizure activity (for example, cloni or respiratory sounds). Pure ictal vo calisation occurred in 11 patients of whom nine had a left frontal epilepto genic zone (p<0.01). It is concluded that ictal vocalisation could be an ad ditional lateralising sign in frontal lobe epilepsy. The results suggest th at not only speech, but vocalisation at a subverbal level also shows a left hemispheric dominance in humans.