Studies on the operative outcomes and mechanisms of microvascular decompression in treating typical and atypical trigeminal neuralgia

Objective: To evaluate the operative outcomes and mechanisms of microvascular decompression in treating typical and atypical trigeminal neuralgia. Methods: A group of 45 patients with typical trigeminal neuralgia and 17 patients with atypical trigeminal neuralgia treated by microvascular decompression from 2000 to 2002 were reviewed, including their clinical presentations, operative findings, and outcomes. Results: Of 45 patients with typical trigeminal neuralgia, the mean duration was 3.1 years, and the mean age of pain onset was 60.3 years. Single trigeminal division was involved in 20 patients (44.4%), and 2 or 3 divisions were involved in the other 25 patients (55.6%). During the operation, artery compression was found in 39 patients (86.7%), and the combined artery and venous compression was found in 6 patients (13.3%). Postoperatively, complete pain relief was achieved in 44 patients (97.8%), and significant pain relief was achieved in 1 patient (2.2%). As for 17 patients with atypical trigeminal neuralgia, the mean duration and the mean age of pain onset was 8.7 years and 55.5 years, respectively. Two or 3 trigeminal divisions were involved in all of these patients. During operation, artery compression occurred in 10 patients (58.8%), and the combined artery and venous compression was found in 7 patients (41.2%). Postoperatively, complete pain relief was achieved in 5 patients (29.4%), and partial pain relief was achieved in 10 patients (58.8%), and 2 patients showed no response to microvascular decompression. Conclusions: The operative outcome of microvascular decompression in patients with typical trigeminal neuralgia was better than that of patients with atypical trigeminal neuralgia, which perhaps related to short duration, late onset of pain, limited distribution, artery compression, and complete operative decompression.