Language mapping with navigated transcranial magnetic stimulation in pediatric and adult patients undergoing epilepsy surgery: Comparison with extraoperative direct cortical stimulation

Abstract

SummaryObjectiveNavigated transcranial magnetic stimulation (nTMS) is becoming increasingly popular in noninvasive preoperative language mapping, as its results correlate well enough with those obtained by direct cortical stimulation (DCS) during awake surgery in adult patients with tumor. Reports in the context of epilepsy surgery or extraoperative DCS in adults are, however, sparse, and validation of nTMS with DCS in children is lacking. Furthermore, little is known about the risk of inducing epileptic seizures with nTMS in pediatric epilepsy patients. We provide the largest validation study to date in an epilepsy surgery population.MethodsWe compared language mapping with nTMS and extraoperative DCS in 20 epilepsy surgery patients (age range 9‐32 years; 14 children and adolescents).ResultsIn comparison with DCS, sensitivity of nTMS was 68%, specificity 76%, positive predictive value 27%, and negative predictive value 95%. Age, location of ictal‐onset zone near or within DCS‐mapped language areas or severity of cognitive deficits had no significant effect on these values. None of our patients had seizures during nTMS.SignificanceOur study suggests that nTMS language mapping is clinically useful and safe in epilepsy surgery patients, including school‐aged children and patients with extensive cognitive dysfunction. Similar to in tumor surgery, mapping results in the frontal region are most reliable. False negative findings may be slightly more likely in epilepsy than in tumor surgery patients. Mapping results should always be verified by other methods in individual patients.

Comparing navigated transcranial magnetic stimulation mapping and “gold standard” direct cortical stimulation mapping in neurosurgery: a systematic review

“…No adverse events are mentioned in the studies. The nTMS language mapping was also well tolerated in pediatric patients according to Lehtinen et al [30]. In the study, 14 pediatric and adolescent patients were included, with an age ranging from 9 to 18 years.…”

“…Only Sollmann et al analyzed the correlation between the type of language error that could be evoked with nTMS mapping and the type of error found with DCS mapping [52]. Lehtinen et al give information about the percentage of true positive nTMS mapped types of language errors in relation to the DCS mapping outcome, which ranged between 14 and 76% [30].…”

“…nTMS mapping has been compared with fMRI mapping in several studies as well. For motor function localization, there is support that nTMS mapping is more accurate than fMRI [3,7,30] and, in addition, the distance between nTMS-and DCSmapped functional regions is smaller than the distance between nTMS-and fMRI-mapped functional regions [23][24][25]. Regarding mapping of language function, nTMS mapping is more sensitive, but less specific than fMRI [2,18].…”

Presurgical Functional Cortical Mapping Using Electromagnetic Source Imaging

“…Impaired memory performance is usually found in about 20–30 % of cases injected ipsilateral to the seizure onset zone and in 60–80% after contralateral injection (117–119). Based on these results, several authors consider IAT results as a prognostic tool to predict postsurgical declarative memory, although results on the predictive value of IAT are contradictory and controversial (120–123), and memory results on repeated IAT are much less robust than those of verbal language testing (15).…”

Impact of Priming on Effectiveness of TMS in Detecting Language-eloquent Brain Areas in Tumor Patients

“…True language-positive areas were considered if the nrTMS and DCS results were within 5 mm of each other. 53 The first patient (patient B1) was a 52-year-old man with a tumor located in the left fronto-temporo-insular region (►Table 2). He consulted because of sudden deafness.…”