Abstracts

Rationale:Electrical stimulation is a useful method to difine eloquent cortex before resection of epileptogenic areas and lesions. We studied language localization and quantitative evaluations in various language tasks using chronically intracranial electrodes stimulation in patients with partial epilepsy. Methods: We implanted subdural grid elctrodes in 37 patients. The mean age was 28 years of age. Stimulation parameters were following, 0.2msec, 50Hz alternative electric currents with intensity of 1-10 mA and duration of 2 to 5 seconds. Language-associated positive and negative motor responses during stimulation were excluded. Language deficits that were consistently reproducible in repetitive trials were considered positive findings. We tested six type of language tasks, spontaneous speech (SS), picture naming (PN), auditory comprehension (AC), responsive naming (RN), reading words and sentenses aloud, and repetition. Results: Anterior language areas were recognized in 15 patients with 61 elcetrodes. No language areas were located at the Broca's area in three patients (20%). At 31% of electrodes, language function was affected in SS tasks, and 72% in PN, 74% in AC, and 52% in RN tasks. Twelve electrodes (20%) were not impaired in both SS and PN tasks, and impaired in AC and/or RN tasks in 7 of 15 patients (47%). Posterior language areas were detected in 21 patients with 133 elcetrodes. Language areas were not demonstrated at the Wernicke's area in five patients (24%) . At 38% of electrodes, language function was affected in SS tasks, and 63% in PN, 73% in AC, and 70% in RN tasks. There is a statistically significance of impairment in RN task between anterior and posterior language areas (p=0.02). Twenty-seven electrodes (21%) were not affected in both SS and PN tasks, and affected in AC and/or RN tasks in 11 of 20 patients (55%). Discussion: Language production and comprehension was affected not only in the anterior but also posterior language areas during cortical stimulation. To differentiate two language areas, responsive naming, which tested auditory comprehension and speech production simultaneously, is useful.