Awake Craniotomy Language Mapping in Children With Drug-Resistant Epilepsy due to Focal Cortical Dysplasia.

BACKGROUND: Language mapping during awake craniotomy can allow for precise resection of epileptogenic lesions, while reducing the risk of damage to eloquent cortex. There are few reports in the literature of language mapping during awake craniotomy in children with epilepsy. Some centers may avoid awake craniotomy in the pediatric age group due to concerns that children are unable to cooperate with such procedures. METHODS: We reviewed pediatric patients from our center with drug-resistant focal epilepsy who underwent language mapping during awake craniotomy and subsequent resection of the epileptogenic lesion. RESULTS: Two patients were identified, both female, aged 17 years and 11 years at the time of surgery. Both patients had frequent and disabling focal seizures despite trials of multiple antiseizure medications. Both patients had resection of their epileptogenic lesions with the aid of intraoperative language mapping; in both cases pathology was consistent with focal cortical dysplasia. Both patients had transient language difficulties in the immediate postoperative period but no deficits at six-month follow-up. Both patients are now seizure-free. CONCLUSIONS: Awake craniotomy should be considered in pediatric patients with drug-resistant epilepsy in whom the suspected epileptogenic lesion is in close proximity to cortical language areas.

Verbal memory and verbal fluency tasks used for language localization and lateralization during magnetoencephalography.

OBJECTIVE: The aim of this study was to develop a presurgical magnetoencephalography (MEG) protocol to localize and lateralize expressive and receptive language function as well as verbal memory in patients with epilepsy. Two simple language tasks and a different analytical procedure were developed. METHODS: Ten healthy participants and 13 epileptic patients completed two language tasks during MEG recording: a verbal memory task and a verbal fluency task. As a first step, principal component analyses (PCA) were performed on source data from the group of healthy participants to identify spatiotemporal factors that were relevant to these paradigms. Averaged source data were used to localize areas activated during each task and a laterality index (LI) was computed on an individual basis for both groups, healthy participants and patients, using sensor data. RESULTS: PCA revealed activation in the left temporal lobe (300 ms) during the verbal memory task, and from the frontal lobe (210 ms) to the temporal lobe (500 ms) during the verbal fluency task in healthy participants. Averaged source data showed activity in the left hemisphere (250-750 ms), in Wernicke's area, for all participants. Left hemisphere dominance was demonstrated better using the verbal memory task than the verbal fluency task (F1,19=4.41, p=0.049). Cohen's kappa statistic revealed 93% agreement (k=0.67, p=0.002) between LIs obtained from MEG sensor data and fMRI, the IAT, electrical cortical stimulation or handedness with the verbal memory task for all participants. At 74%, agreement results for the verbal fluency task did not reach statistical significance. SIGNIFICANCE: Analysis procedures yielded interesting findings with both tasks and localized language-related activation. However, based on source localization and laterality indices, the verbal memory task yielded better results in the context of the presurgical evaluation of epileptic patients. The verbal fluency task did not add any further information to the verbal memory task as regards language localization and lateralization for most patients and healthy participants that would facilitate decision making prior to surgery.

Language tasks used for the presurgical assessment of epileptic patients with MEG.

Determining the language dominant hemisphere and the intrahemispheric localization of this function are imperative in the planning of neurosurgical procedures in epileptic patients. New noninvasive diagnostic techniques are being developed to reduce the risks associated with more invasive techniques. The aim of this paper is to review the different protocols for lateralizing and/or localizing language functions using magnetoencephalography (MEG), a noninvasive technique. The reviewed studies include control and patient populations using various protocols which employ different expressive and receptive language tasks. The overall findings reveal high concordance between MEG and the intracarotid amobarbital test (IAT). Moreover, MEG allows intrahemispheric localization of receptive and expressive language functions. However, the different language tasks used with MEG, whether receptive or expressive, appear to activate the left temporal more than frontal areas. The best task to assess language comprehension in both adults and children appears to be a word recognition task. A verbal fluency task could be used to test language production in children and a verb generation task in adults.