gms | German Medical Science

Objective: Neurovascular compression is characterized by a complex, three-dimensional neurovascular relationship at the root entry zones causing syndromes such as cranial nerve neuralgia (trigeminal, glossopharyngeal) and vertigo. Microneurovascular decompression requires 3D experience within the cisternal spaces to achieve sufficient clinical results. Indication was traditionally based on clinical decisions, only. New MR techniques have become available, and their chances and potential impact should be evaluated.

Method: We examined 14 recent consecutive patients with trigeminal neuralgia and one patient with chronic vertigo attacks regarding the details of the NVC sites with high resolution MRI in correlation to the intraoperative findings. 7 of 14 patients (50%) with TN and one patient with vertigo underwent 1.5T imaging with T2 fast spin echo. The other 7 patients with TN did not undergo preoperative MRI. The MRI data were retrospectively analyzed and compared to the intraoperative findings with the focus on the length of the cranial nerve and topography of the vascular compression site especially the distance of the location of the compression from the surface of the brainstem.

Results: The SCA was the most common causative vessel in 10 of 14 cases (71%), AICA in 3 of 14 cases (21%) and veins in 1 of 14 cases (7%). The cisternal length of the examined trigeminal nerve on MRI at the affected side ranged from 8,1mm-10,8mm and on the unaffected contralateral sides from 9,4mm-11,4mm; the vestibular nerve in one vertigo patient had an equal cisternal length of 18mm on either side, whereas the distance of the neurovascular conflict site was 8mm from the surface of the flocculus. The distance of the neurovascular conflict location site to the brainstem ranged from 1,4mm to 8,5mm on the reviewed MR image slices. One patient with vertigo showed an AICA loop in the MRI, which was confirmed intraoperatively. All causative vessels on the trigeminal nerve performed loops from cranial to caudal. Upon follow-up, 12 of 14 patients with TN were painfree (mean 2.5 years). 2 of 14 patients (14%) with TN showed pain recurrence. The patient with vertigo was symptom-free postoperatively.

Conclusions: We show that highly resoluted MRI provides reliable and detailed information on corresponding intraoperative anatomy. Especially in unusual cases, the application of such MR techniques and preoperative evaluation may contribute to indication, planning, and also for teaching purposes.