Image-guided TMS is safe in a predominately pediatric clinical population.

OBJECTIVE: The safety of transcranial magnetic stimulation (TMS) has been previously evaluated in healthy volunteers and clinical adult populations. We sought to fill the gap in safety of TMS functional mapping in a clinical, predominately pediatric cohort. METHODS: In a retrospective chart review, we assessed TMS motor and language mapping studies in persons with epilepsy or brain tumor for adverse events and safety of TMS, and in patients with cranial metal. RESULTS: Out of 500 TMS sessions attempted in 429 individual patients (51% males, 82% ≤ 18 y), seizures occurred in 29 sessions (5.8%) during or after TMS with semiology consistent with their typical presentation and 53 patients (10.6%) experienced pain during stimulation. TMS was completed safely in 276 patients with cranial metal. CONCLUSIONS: Most TMS-related adverse events were benign and transient; the most serious safety events were seizures that could not be conclusively attributed to TMS. However, useful mapping results were obtained in almost all patients. Presence of cranial metal did not adversely affect TMS mapping. We show that TMS functional mapping is safe in a largely pediatric clinical cohort. SIGNIFICANCE: This study demonstrates the safety of TMS functional mapping in patients with refractory epilepsy, brain tumor or cranial metal and fills a gap in knowledge for TMS safety in pediatric clinical population.

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.

Accurate presurgical mapping of motor, speech, and language cortices, while crucial for neurosurgical planning and minimizing post-operative functional deficits, is challenging in young children with neurological disease. In such children, both invasive (cortical stimulation mapping) and non-invasive functional mapping imaging methods (MEG, fMRI) have limited success, often leading to delayed surgery or adverse post-surgical outcomes. We therefore examined the clinical utility of transcranial magnetic stimulation (TMS) in young children who require functional mapping. In a retrospective chart review of TMS studies performed on children with refractory epilepsy or a brain tumor, at our institution, we identified 47 mapping sessions in 36 children 3 years of age or younger, in whom upper and lower extremity motor mapping was attempted; and 13 children 5-6 years old in whom language mapping, using a naming paradigm, was attempted. The primary hand motor cortex was identified in at least one hemisphere in 33 of 36 patients, and in both hemispheres in 27 children. In 17 children, primary leg motor cortex was also successfully identified. The language cortices in temporal regions were successfully mapped in 11 of 13 patients, and in six of them language cortices in frontal regions were also mapped, with most children (n = 5) showing right hemisphere dominance for expressive language. Ten children had a seizure that was consistent with their clinical semiology during or immediately following TMS, none of which required intervention or impeded completion of mapping. Using TMS, both normal motor, speech, and language developmental patterns and apparent disease induced reorganization were demonstrated in this young cohort. The successful localization of motor, speech, and language cortices in young children improved the understanding of the risk-benefit ratio prior to surgery and facilitated surgical planning aimed at preserving motor, speech, and language functions. Post-operatively, motor function was preserved or improved in nine out of 11 children who underwent surgery, as was language function in all seven children who had surgery for lesions near eloquent cortices. We provide feasibility data that TMS is a safe, reliable, and effective tool to map eloquent cortices in young children.