Microvascular decompression for trigeminal neuralgia: the importance of a noncompressive technique--Kaplan-Meier analysis in a consecutive series of 330 patients.

OBJECTIVE: Microvascular decompression, although a well-established procedure for treating primary trigeminal neuralgia, still has no standardized protocol. The practical consequences of having the implant keep the conflicting vessels apart, whether or not in contact with the root, is still in debate. The present work was undertaken to answer this question.
METHODS: Patients were segregated into 2 groups: Group I (260 patients) had a Teflon prosthesis implanted without contact to the root, and Group II (70 patients) had a similar implant with contact to the root. Cure rates in the 2 groups were compared at the latest follow-up (</=15 yr; average, 8.2 yr) using Kaplan-Meier analysis.
RESULTS: In Group I, the cure rate was 82% (214 of 260 patients), whereas in Group II, the cure rate was 67% (47 of 70 patients) (P = 0.01). Kaplan-Meier analysis of the follow-up period up to 15 years also shows a significant difference (P = 0.05).
CONCLUSION: These results strongly support the goal of performing the procedure without the implant in contact with the root. This is easier with the superior cerebellar artery, because of its laxity and small number of perforating branches, than with the anteroinferior cerebellar artery, which has perforators to the brainstem and labyrinthine artery arising from its cisternal portion. The significantly better long-term cure rate when the implant is not in contact with the root favors the "pure" decompressive effect of the microvascular decompression procedure, rather than a conduction block mechanism.