Anatomical findings in microsurgical vascular decompression for trigeminal neuralgia. Correlations between topography of pain and site of the neuro-vascular conflict.

We here report on the anatomical findings in a series of 350 patients with trigeminal neuralgia (TN) and operated on using a microsurgical key-hole approach to the CPA. In 5.7% there was a tumour or a vascular malformation, in 2.3% a mega-vertebro-basilar-artery. Among the remaining 322 (= real idiopathic TN), only 3.1% had no visible compressive factor, whilst 96.9% had one (or several) conflicting vessel(s): SCA in 90%, AICA in 23.6%, a vein in 24.7%. In 35.7% of the patients, several neurovascular conflicts (NVC) were found. Beside the NVC(s), a global atrophy of the entire root was seen in 67% of the cases. Degree of severity of the NVC and its site along the root were studied. The site of the conflict was: anteriorly to the root when pain was in V1, anteriorly and superiorly when in V2, superiorly and posteriorly when in V3.