Reorganization and stability for motor and language areas using cortical stimulation: case example and review of the literature.

Sandra Serafini,Mohamad Mikati,Jordan Komisarow,Michael Haglund,Peter Kranz,Gerald Grant,Melanie Bonner,William Gallentine

doi:10.3390/brainsci3041597

Abstract

The cerebral organization of language in epilepsy patients has been studied with invasive procedures such as Wada testing and electrical cortical stimulation mapping and more recently with noninvasive neuroimaging techniques, such as functional MRI. In the setting of a chronic seizure disorder, clinical variables have been shown to contribute to cerebral language reorganization underscoring the need for language lateralization and localization procedures. We present a 14-year-old pediatric patient with a refractory epilepsy disorder who underwent two neurosurgical resections of a left frontal epileptic focus separated by a year. He was mapped extraoperatively through a subdural grid using cortical stimulation to preserve motor and language functions. The clinical history and extensive workup prior to surgery is discussed as well as the opportunity to compare the cortical maps for language, motor, and sensory function before each resection. Reorganization in cortical tongue sensory areas was seen concomitant with a new zone of ictal and interictal activity in the previous tongue sensory area. Detailed neuropsychological data is presented before and after any surgical intervention to hypothesize about the extent of reorganization between epochs. We conclude that intrahemispheric cortical plasticity does occur following frontal lobe resective surgery in a teenager with medically refractory seizures.

Highlights

Refractory epilepsy in children may lead to resective surgery if the epileptogenic zone can be localized
We report the case of a pediatric patient who underwent two surgical resections of a left frontal seizure focus at the ages of 12 and 13 and four serial neuropsychological assessments at the ages of 6, 10, 13 and 14
Speech arrest and hesitations in this area are associated more with a speech-motor function than a frontal language function. This is consistent with visual naming deficits being relatively rare in frontal lobe epilepsy pediatric patients [35] and the location of visual naming errors during cortical stimulation found more superiorly in the MFG [4], likely as a result of terminations of the arcuate fasciculus, which is implicated in various aspects of language [25,36]

Summary

Introduction

Refractory epilepsy in children may lead to resective surgery if the epileptogenic zone can be localized. A subdural grid array is surgically placed on the brain to better delineate the margins of the epileptogenic zone and to perform extraoperative electrical cortical stimulation (ECS) Together, these localization techniques provide information to pinpoint the epileptic focus that should be removed as well as identify the areas for motor, sensory, and language function so they can be avoided to minimize post-operative functional deficits. Resections of language areas in pediatric patients that result in either expressive or receptive language deficits in the early postoperative period are able to reorganize intrahemispherically [4] This intrahemispheric cortical plasticity and postlesional functional reorganization is thought to depend on the preservation of white matter tracts, and so far it appears that damage to white matter precludes structural plasticity [5]. Reorganization is discussed in a context of possible age-related changes versus changes induced by pathology or surgically-induced functional changes in frontal areas

History and Neurological Examination

Neuropssychologicaal Assessmeents

Grid Mapping 1

Fiber Tracking

Conclusions