Reorganization and Stability for Motor and Language Areas Using Cortical Stimulation: Case Example and Review of the Literature

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.

Chronic ambulatory electrocorticography from human speech cortex

“…The opportunity to record iEEG also occurs frequently arises when patients with drug-resistant epilepsy are implanted with intracranial electrodes to localize seizures prior to surgical treatment (Shah and Mittal, 2014). In this context, there are several limitations to iEEG: (1) Experimental sessions are limited by the occurrence of seizures, effects of medication changes, and suboptimal patient participation due to pain, fatigue, and other factors related to the inpatient environment (Hill et al, 2012); (2) Recordings to localize the seizure onset zone rarely extend beyond 1–2 weeks due to infection risk, degradation of signal quality, inability to perform recordings outside the hospital setting, and achievement of clinical goals (Shah and Mittal, 2014); (3) Serial iEEG investigations over time are uncommon, electrode coverage cannot be precisely reproduced during subsequent implantations, and ongoing seizures can distort functional organization in sensory cortex (Serafini et al, 2013). …”

Neuroplasticity and Epilepsy Surgery in Brain Eloquent Areas: Case Report

“…CSM has long been used to identify eloquent areas in the presurgical study and to demarcate epileptogenic sites. CSM has also confirmed the plastic potential of brains in childhood and adolescence ( 7 , 8 ). There has been abundant research on the application of CSM in animal models of neuronal plasticity modification ( 9 – 11 ).…”

Semiotic Principles in Cognitive Neuroscience

“…This technique was developed in order to identify areas related to important functions of production (motor) and comprehension (sensory) in language(s) and has proven successful in preserving these functions in surgeries that require removal of tissue. Dr. Ojemann has published over 170 papers of CSM data with important conclusions about neural mappings of language and languages [29][30][31][32][33][34][35][36][37][38][39][40][41].…”