Pre-operative transcranial magnetic stimulation useful for language mapping

Image: PD

1. When compared to gold standard direct intraoperative cortical stimulation (DCS), pre-operative navigational transcranial magnetic stimulation (nTMS) showed an overall sensitivity of 90.2% for detecting language areas. 

2. nTMS had a sensitivity of 100% for broca’s area when compared with DCS. 

Evidence Rating Level: 2 (Good) 

Study Rundown: nTMS is a cutting edge tool for pre-operative brain mapping that is gaining wider acceptance and utilization. It already has demonstrated efficacy in identification of the motor cortex when compared with the gold-standard DCS. This study demonstrates good overall correlation between repetitive nTMS and DCS for language areas. Given its high sensitivity for language areas, this technique is especially useful for generating negative response maps to help surgeons avoid language regions during craniotomies and resections. However, the technique also had low specificity for positively identifying language areas and further refinements are needed.

Click to read the study in Neurosurgery

Relevant Reading: Navigated transcranial magnetic stimulation for preoperative functional diagnostics in brain tumor surgery

In-Depth [prospective study]: This study was conducted on 20 consecutive patients with tumors in the vicinity of eloquent regions of the brain. Patients were examined with nTMS pre-operatively, then underwent intraoperative awake DCS. Results from both studies were compared to evaluate the accuracy of nTMS. Pre-operative nTMS maps demonstrated an overall sensitivity of 90.2% and overall specificity of 23.8% for language areas when compared to DCS. nTMS sensitivity for identifying the anatomy broca’s area was 100%. Ultimately, 7 out of the 20 patients still had some evidence of aphasia one week post-operatively.

By Allen Ho

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