Robot-assisted image-guided transcranial magnetic stimulation for somatotopic mapping of the motor cortex: a clinical pilot study.
OBJECTIVE
Shape and exact location of motor cortical areas varies among individuals. The exact knowledge of these locations is crucial for planning of neurosurgical procedures. In this study, we have used robot-assisted image-guided transcranial magnetic stimulation (Ri-TMS) to elicit MEP response recorded for individual muscles and reconstruct functional motor maps of the primary motor cortex.


METHODS
One healthy volunteer and five patients with intracranial tumors neighboring the precentral gyrus were selected for this pilot study. Conventional MRI and fMRI were obtained. Transcranial magnetic stimulation was performed using a MagPro X100 stimulator and a standard figure-of-eight coil positioned by an Adept Viper s850 robot. The fMRI activation/Ri-TMS response pattern were compared. In two cases, Ri-TMS was additionally compared to intraoperative direct electrical cortical stimulation.


RESULTS
Maximal MEP response of the m. abductor digiti minimi was located in an area corresponding to the "hand knob" of the precentral gyrus for both hemispheres. Repeated Ri-TMS measurements showed a high reproducibility. Simultaneous registration of the MEP response for m. brachioradialis, m. abductor pollicis brevis, and m. abductor digiti minimi demonstrated individual peak areas of maximal MEP response for the individual muscle groups. Ri-TMS mapping was compared to the corresponding fMRI studies. The areas of maximal MEP response localized within the "finger tapping" activated areas by fMRI in all six individuals.


CONCLUSIONS
Ri-TMS is suitable for high resolution non-invasive preoperative somatotopic mapping of the motor cortex. Ri-TMS may help in the planning of neurosurgical procedures and may be directly used in navigation systems.
Kantelhardt
Sven Rainer
SR
Department of Neurosurgery, Georg-August University of Göttingen, Robert-Koch-Strasse 40, 37075 Göttingen, Germany. sven.kantelhardt@med.uni-goettingen.de
Fadini
Tommaso
T
Finke
Markus
M
Kallenberg
Kai
K
Siemerkus
Jakob
J
Bockermann
Volker
V
Matthaeus
Lars
L
Paulus
Walter
W
Schweikard
Achim
A
Rohde
Veit
V
Giese
Alf
A
D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D038361:Neuronavigation / Q000295:instrumentation / Q000379:methods*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000295:instrumentation / Q000379:methods*; D012371:Robotics / Q000295:instrumentation / Q000379:methods*; D050781:Transcranial Magnetic Stimulation / Q000295:instrumentation / Q000379:methods*