Arterial compression of nerve is the primary cause of trigeminal neuralgia.

Whether arterial or venous compression or arachnoid adhesions are primarily responsible for compression of the trigeminal nerve in patients with trigeminal neuralgia is unclear. The aim of this study was to determine the causes of trigeminal nerve compression in patients with trigeminal neuralgia. The surgical findings in patients with trigeminal neuralgia who were treated by micro vascular decompression were compared to those in patients with hemifacial spasm without any signs or symptoms of trigeminal neuralgia who were treated with microvascular decompression. The study included 99 patients with trigeminal neuralgia (median age, 57 years) and 101 patients with hemifacial spasm (median age, 47 years). There were significant differences between the groups in the relationship of artery to nerve (p < 0.001) and the presence of arachnoid adhesions (p < 0.001) but no significant difference in relationship of vein to nerve. After adjustment for age, gender, and other factors, patients with vein compression of nerve or with artery compression of nerve were more likely to have trigeminal neuralgia (OR = 5.21 and 42.54, p = 0.026 and p < 0.001, respectively). Patients with arachnoid adhesions were less likely to have trigeminal neuralgia (OR = 0.15, p = 0.038). Arterial compression of the trigeminal nerve is the primary cause of trigeminal neuralgia and therefore, decompression of veins need not be a priority when performing microvascular dissection in patients with trigeminal neuralgia.