Cortical localization in epilepsy

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Project Summary/Abstract The ability to produce the correct words while speaking is critical for normal social, academic and occupational functioning. Unfortunately, for many children with uncontrolled epilepsy, surgical treatment for seizure control can place these vital language skills at risk. Extensive research in adults with refractory epilepsy has shown significant risk to word production or “naming” ability that can be predicted before surgery based on clinical factors and, in some cases, prevented using preoperative language mapping. In marked contrast, we are currently unable to predict risk to expressive language in children, and the mapping techniques currently utilized have failed to reliably identify and protect language cortex in children. This represents a serious gap in clinical care, as prediction and protection of language are critical during development. A key problem has been the approach to naming in children, both in behavioral assessment and in preoperative language mapping. Significant advances in the neuroscience of naming have shown that traditional methods, which rely solely on visual object naming without regard to speed of response and other cognitive features of naming, can miss true naming deficits in assessment, and fail to identify essential naming areas in cortical language mapping. In adults, the addition of auditory description naming to preoperative assessment has assisted in lateralization of dysfunction related to epileptogenic cortex, and has improved mapping efficacy by identifying critical language cortex that otherwise remained undetected. We recently developed pediatric auditory naming and complementary visual naming measures that showed significant sensitivity to lateralized epilepsy-related dysfunction in preoperative children with refractory epilepsy. These measures now enable accurate and detailed assessment of naming in children. This project will use these recently developed tests, pre and postoperatively, and in cortical language mapping to: 1) identify the factors that predict both short- and long- term postoperative decline, 2) determine when decline is global or limited to one modality, and 3) determine whether modality-based naming can more effectively identify and protect language cortex in children. Results promise empirically based knowledge of risk to postoperative verbal skills in children with refractory epilepsy, improved language mapping in children, and advances in the cognitive neuroscience of language development and recovery. With increasing numbers of children undergoing epilepsy surgery, we can expect a growing need for accurate prediction, protection and measurement of pediatric language outcome.