Noninvasive Localization of Language Cortex in an Awake 4-Year-Old Child with Rasmussen Encephalitis: A Case Report

Abstract

BACKGROUND AND IMPORTANCE Presurgical mapping of eloquent cortex in young patients undergoing neurosurgery is critical for timely intervention, surgical planning, and minimizing postoperative deficits. However, invasive direct cortical stimulation has limited success in young children and noninvasive modalities, such as magnetoencephalography and functional MRI, require sedation, often precluding localization of critical language cortices. Transcranial magnetic stimulation (TMS), a noninvasive brain stimulation technique, is well suited to evaluate language areas in young children because it does not require the patient to remain still during mapping. CLINICAL PRESENTATION A 4-yr and 11-mo-old female patient diagnosed with epilepsia partialis continua of the right arm and face and right-sided weakness was evaluated at our institution. MRI findings and clinical examination led to the diagnosis of Rasmussen encephalitis involving left frontal lobe and insula. Language cortices were successfully identified in both hemispheres using TMS. The TMS findings aided in discussing with the family the risks of postsurgical deficits of left functional hemispherectomy, the definitive treatment for Rasmussen encephalitis. Postoperatively, the patient had intact speech and was seizure free. CONCLUSION We illustrate the feasibility and utility of TMS as a noninvasive functional mapping tool in this young child. The preoperative demonstration of bilateral language organization indicated a greater likelihood of preserved language functions postsurgery. We demonstrate that TMS is a safe and noninvasive tool to map language cortices in young children with serious epilepsy syndromes.

Clinical Utility of Transcranial Magnetic Stimulation (TMS) in the Presurgical Evaluation of Motor, Speech, and Language Functions in Young Children With Refractory Epilepsy or Brain Tumor: Preliminary Evidence

“…The color-naming task was used in eight children (see Figure 1B for example) and an object-naming task was used in five children. We have previously shown that young and developmentally delayed children who could not consistently name objects could still name colors accurately and have successfully used the color-naming task to successfully map speech and language in this cohort (32,45). In other children, pictures of objects included in the NexSpeech module was used (46).…”

“…We have previously reported a small case-series of six children under the age of 3 years who underwent TMS motor mapping at our institution ( 20 ) and on the utility of TMS motor mapping in an infant with cortical dysplasia ( 31 ). We have also reported a case study of a 4-year 11-month-old child who underwent successful TMS language mapping ( 32 ). In this paper we aim to further assess whether reliable motor maps can be derived in very young children with neurological disorders and evaluate the safety and tolerability of TMS in a larger cohort of children younger than 3 years.…”