Frameless stereotactic cannulation of the foramen ovale for ablative treatment of trigeminal neuralgia.
OBJECTIVE
Ablative neurosurgical treatment of trigeminal neuralgia, including percutaneous radiofrequency thermocoagulation, requires cannulation of the foramen ovale. To maximize patient security and cannulation success, a frameless stereotactic system was evaluated in a phantom study, a cadaveric study, and a preliminary clinical trial.


METHODS
Frameless stereotaxy using an optical navigation system, an aiming device, and a noninvasive vacuum mouthpiece-based registration and patient fixation technique was used for the targeting of a test body based on 1-, 3-, and 5-mm axial computed tomographic slices and of the foramen ovale in three cadavers and 15 patients based on 3-mm axial computed tomographic slices.


RESULTS
The mean normal (x/y) localization accuracy/standard deviation (n = 360) was 1.31/0.67 mm (1-mm slices), 1.38/0.65 mm (3-mm slices), and 1.84/0.96 mm (5-mm slices). Significantly better results were achieved with 1- and 3-mm slices when compared with 5-mm slices (P < 0.001). The foramen ovale (3 x 6 mm) was successfully cannulated at the first attempt in all cadavers and patients, which indicates clinical localization accuracies better than 1.5 mm in the anteroposterior and 3 mm in the medial-lateral directions.


CONCLUSIONS
Based on the noninvasive Vogele-Bale-Hohner vacuum mouthpiece, there is no need for invasive head clamp fixation. Imaging, real laboratory simulation, and the actual surgical intervention can be separated in time and location. The presented data suggest that frameless stereotaxy is a predictable and reproducible procedure, which may enhance patient security and cannulation success independent of the surgeon's experience.
Bale
Reto J
RJ
Department of Radiology, Medical University Innsbruck, Innsbruck, Austria. reto.bale@uibk.ac.at
Laimer
Ilse
I
Martin
Arno
A
Schlager
Andreas
A
Mayr
Christoph
C
Rieger
Michael
M
Czermak
Benedikt V
BV
Kovacs
Peter
P
Widmann
Gerlig
G
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D002404:Catheterization / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006346:Heart Septum / Q000473:pathology* / Q000601:surgery; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D013238:Stereotaxic Techniques; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome; D014277:Trigeminal Neuralgia / Q000473:pathology / Q000601:surgery*