OBJECTIVES: The etiology of trigeminal neuralgia (TN) without neurovascular conflict (NVC) is undetermined and classic neurovascular decompression procedures are not applicable. We analyzed a potential etiology in patients operated for TN without NVC. MATERIAL: Clinical, radiological and treatment outcome data were retrospectively reviewed in a consecutive cohort of 37 patients afflicted with medically intractable TN without detectable NVC on preoperative 3T-MRI nor during surgery. All patients underwent endoscopic-assisted microsurgical trigeminal nerve release from tethering arachnoid between January 2019 and December 2023. Intraoperative findings were compared to those of a control group of 22 patients undergoing surgery for other pathologies within the cerebellopontine angle (CPA). RESULTS: Median age of the 24 women and 13 men with TN was 58 years (IQR 48-71). Mean preoperative pain intensity on the VAS scale and BNI was 9.5/10 and 5, respectively. Surgical exploration revealed an arachnoid-nerve conflict in all cases of TN (cohort group) and in only two patients of the control group (p<
0.001). Release of the trigeminal nerve from its anchoring arachnoid yielded in significant postoperative improvement of VAS (1.6/10, p<
0.001) and 84 % of the TN-patients achieved pain- and medication freedom (BNI 1) after a median postoperative follow-up of 24 months (IQR 7-46). CONCLUSIONS: An arachnoid-nerve conflict seems to play a pivotal role in the etiology of TN without NVC. Trigeminal nerve release from tethering arachnoid effectively achieves pain relief and medication independence.