Abstract
BackgroundLanguage mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is used for resection planning in patients suffering from brain lesions within regions known to be involved in language function. Yet we also need data that show whether patients benefit clinically from preoperative rTMS for language mapping.MethodsWe enrolled 25 patients with language eloquently located brain lesions undergoing preoperative rTMS language mapping (GROUP 1, 2011–2013), with the mapping results not being available for the surgeon, and we matched these patients with 25 subjects who also underwent preoperative rTMS (GROUP 2, 2013–2014), but the mapping results were taken into account during tumor resection. Additionally, cortical language maps were generated by analyzing preoperative rTMS and intraoperative direct cortical stimulation (DCS) data.ResultsMean anterior-posterior (ap) craniotomy extents and overall craniotomy sizes were significantly smaller for the patients in GROUP 2 (Ap: p = 0.0117; overall size: p = 0.0373), and postoperative language deficits were found significantly more frequently for the patients in GROUP 1 (p = 0.0153), although the preoperative language status did not differ between groups (p = 0.7576). Additionally, there was a trend towards fewer unexpected tumor residuals, shorter surgery duration, less peri- or postoperative complications, shorter inpatient stay, and higher postoperative Karnofsky performance status scale (KPS) for the patients in GROUP 2.ConclusionsThe present study provides a first hint that the clinical course of patients suffering from brain tumors might be improved by preoperative rTMS language mapping. However, a significant difference between both groups was only found for craniotomy extents and postoperative deficits, but not for other clinical parameters, which only showed a trend toward better results in GROUP 2. Therefore, multicenter trials with higher sample sizes are needed to further investigate the distinct impact of rTMS language mapping on the clinical course of brain tumor patients.
Highlights
Language mapping by repetitive navigated transcranial magnetic stimulation is used for resection planning in patients suffering from brain lesions within regions known to be involved in language function
Characteristics of patients and lesions Subject-related characteristics including age, gender, lesion histology, lesion diameter, initial Karnofsky performance status scale (KPS) scores, and preoperative language function status are provided in Table 1 for both patient groups
Pre- and intraoperative language mapping Preoperative mapping by repetitive navigated transcranial magnetic stimulation (rTMS) In general, all enrolled patients successfully underwent language mapping by rTMS, and clear no-response errors were detectable during video analysis
Summary
Language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is used for resection planning in patients suffering from brain lesions within regions known to be involved in language function. The induced electrical field is able to transiently modulate cortical neuronal activation, and, when applied during an object naming task, this neuronal modulation can cause transient, audibly detectable impairment of language [4,8]. In selected cases, this approach was even superior to functional magnetic resonance imaging (fMRI) for detection of language-related cortical areas [2]. It is increasingly used for presurgical planning in neurosurgery, data about the impact of rTMS language mapping on the clinical course and outcome parameters are still lacking, and the potential of this comparatively new modality has not yet been under systematical investigation
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