Comparison of functional MR imaging guidance to electrical cortical mapping for targeting selective motor cortex areas in neuropathic pain: a study based on intraoperative stereotactic navigation.
OBJECTIVE
To assess the concordance between data from functional MR imaging (fMRI) guidance and the intraoperative electrical cortical mapping (iCM) in targeting selective motor cortex areas in refractory neuropathic pain.


METHODS
Twenty-one patients (11 women and 10 men; mean age, 55.6 years) with refractory central (ischemic, 8 cases) and neuropathic pain (trigeminal neuropathy, 6 cases; syrinx/amputation/plexus trauma, 7 cases) underwent surgery for the implantation of an epidural electrode for chronic motor cortex stimulation (MCS) with general anesthesia and a frameless neuronavigation system used for the image-guided targeting procedure. All patients were studied by preoperative fMRI and epidural iCM with somatosensory evoked potentials and motor cortex stimulodetection. fMRI investigated systematically motor tasks of both hands and that related to the somatic area (foot or tongue) affected by pain. fMRI data were analyzed with the Statistical Parametric Mapping99 software (initial analysis threshold [AT] corresponding to P < .001), registered in the neuronavigation system and correlated intraoperatively with iCM. Matching of fMRI and iCM was specifically examined, focusing the study on hand mapping.


RESULTS
Concordance between contours of fMRI activation area and iCM in precentral gyrus (mean distance, 3.8 mm) was found in 20/21 patients (95%). Because precision of iCM was suboptimal in 7 patients, concordance for more restrictive values of the AT (P < .0001) was found in only 13 of these 20 patients. Concordance was not found in one patient, as result of image distortion and residual motion artifact.


CONCLUSIONS
In this study, fMRI guidance provides information that matches those of an independent functional method. These data illustrate the functional accuracy of fMRI guidance for the operative targeting of selective motor cortex areas in neuropathic pain.
Pirotte
Benoit
B
Department of Neurosurgery, Erasme Hospital, University of Brussels, Brussels, Belgium.
Neugroschl
Carine
C
Metens
Thierry
T
Wikler
David
D
Denolin
Vincent
V
Voordecker
Philippe
P
Joffroy
Alfred
A
Massager
Nicolas
N
Brotchi
Jacques
J
Levivier
Marc
M
Baleriaux
Danielle
D
D000328:Adult; D000368:Aged; D001931:Brain Mapping; D046690:Deep Brain Stimulation; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009422:Nervous System Diseases / Q000150:complications*; D038361:Neuronavigation; D010146:Pain / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery*; D013238:Stereotaxic Techniques