The Impact of Diffusion Tensor Imaging Fiber Tracking of the Corticospinal Tract Based on Navigated Transcranial Magnetic Stimulation on Surgery of Motor-Eloquent Brain Lesions

BACKGROUND:Navigated transcranialmagnetic stimulation (nTMS) enables preoperativemapping of the motor cortex (M1). The combination of nTMSwith diffusion tensor imagingfiber tracking (DTI-FT) of the corticospinal tract (CST) has been described; however, itsimpact on surgery of motor-eloquent lesions has not been addressed.OBJECTIVE: To analyze the impact of nTMS-based mapping on surgery ofmotor-eloquentlesions.METHODS: In this retrospective case-control study, we reviewed the data of patientsoperated for suspected motor-eloquent lesions between 2012 and 2015. The patientsunderwent nTMS mapping of M1 and, from 2014, nTMS-based DTI-FT of the CST. Theimpact on the preoperative risk/benefit analysis, surgical strategy, craniotomy size, extentof resection (EOR), and outcome were compared with a control group.RESULTS: We included 35 patients who underwent nTMS mapping of M1 (group A), 35patients who also underwent nTMS-based DTI-FT of the CST (group B), and a control groupcomposed of 35 patients treated without nTMS (group C). The patients in groups A and Breceived smaller craniotomies (P = .01; P = .001), had less postoperative seizures (P = .02),and a better postoperativemotor performance (P=.04) and Karnofsky Performance Status(P=.009) than the controls. Group B exhibited an improved risk/benefit analysis (P=.006),an increased EOR of nTMS-negative lesions in absence of preoperative motor deficits(P = .01), and less motor and Karnofsky Performance Status worsening in case of preoperativemotor deficits (P = .02, P = .03) than group A.CONCLUSION: nTMS-based mapping enables a tailored surgical approach for motoreloquentlesions. It may improve the risk/benefit analysis, EOR and outcome, particularlywhen nTMS-based DTI-FT is performed.