TMS as a Tool for Mapping the Dynamic Properties of Language in the Brain
Lateralization and localization of language in the brain is a critical component of surgical planning for patients with epilepsy or brain tumors who require neurosurgical intervention. Accurate language mapping allows the surgeon to conduct the most aggressive surgery possible, enhancing the chance for cure, while avoiding regions critical for language function; striking this balance is critical for maximizing the patient’s quality of life. A range of invasive and non-invasive language mapping techniques are available. This chapter provides a comparative analysis of these techniques and offers a detailed discussion on a newer, non-invasive method called transcranial magnetic stimulation (TMS). Using a superficial coil placed on the scalp, TMS generates a magnetic field that creates a temporary “virtual lesion” in the brain, thereby delineating eloquent cortex. TMS is a safe and well-tolerated procedure for both pediatric and adult populations which closely mimics the “gold-standard” invasive mapping techniques. TMS is becoming an integral component of neurosurgical planning and also shows promise as a research tool for studying typical language development and function in healthy populations.
