Identification of the pyramidal tract by neuronavigation based on intraoperative magnetic resonance tractography: correlation with subcortical stimulation.
OBJECTIVE
To demonstrate the accuracy of magnetic resonance tractograpghy (MRT) in localizing the cortical spinal tract (CST) close to brain tumours by using intraoperative electric subcortical stimulation.


METHODS
Nine patients with intra-axial brain tumours underwent neurosurgery. Planning was based on analysis of the course of streamlines compatible with the CST. After tumour removal, intraoperative MRT was reacquired. Sites at various distance from the CST were repeatedly stimulated to assess whether registered motor evoked potential (MEP) could be elicited. All patients were assessed clinically both pre- and postoperatively.


RESULTS
The motor function was preserved in all patients. In all patients intraoperative MRT demonstrated shift of the bundle position caused by the surgical procedure. The distance between the estimated intraoperative CST and the point of elicited MEP was 1 cm or less in all nine patients. At distances greater than 2 cm, no patient reported positive MEP.


CONCLUSIONS
Intraoperative MRT is a reliable technique for localization of CST. In all patients MEP were elicited by direct subcortical electrical stimulation at a distance below 1 cm from the CST as represented by MRT. Brain shifting might impact this evaluation since CST position may change during surgery in the range of 8 mm.
Bozzao
Alessandro
A
Department of Neuroradiology, University of Rome Sapienza, Ospedale Sant'Andrea, Via di Grottarossa 1034, 00189, Rome, Italy. alessandro.bozzao@uniroma1.it
Romano
Andrea
A
Angelini
Albina
A
D'Andrea
Giancarlo
G
Calabria
Luigi Fausto
LF
Coppola
Valeria
V
Mastronardi
Luciano
L
Fantozzi
Luigi Maria
LM
Ferrante
Luigi
L
D000368:Aged; D001921:Brain / Q000473:pathology / Q000601:surgery; D001931:Brain Mapping / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods; D019635:Neurosurgical Procedures / Q000379:methods; D011712:Pyramidal Tracts / Q000473:pathology*; D015203:Reproducibility of Results
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