Objective To explore the efficacy ofmicrovascular decompression (MVD) for trigeminal neuralgia and the anatomical characteristics of the responsible blood vessels.Methods In a study of using MVD for the treatment of 136 cases with trigeminal neuralgia,the origins of the responsible blood vessels and sites of compression at the trigeminal root were observed and determined, and the anatomical characteristics of the responsible blood vessels and their efficacy correlation were analyzed.Results The number of the responsible blood vessels of superior cerebellar artery (SCA) lateral branches compressing the upper surface of the trigeminal nerve was 80 sides (58.8%),which was mostly frequently observed;the number of anterior inferior cerebellar artery (AICA) branches compressing the lower surface of the trigeminal nerve was 20 sides (14.7%),which was not so frequently observed;the number of two arteries respectively compressing the upper and lower surfaces of the trigeminal nerve was 18 sides (13.2%);the number of sole veins compressing the trigeminal root was 12 sides (8.8%);and,the number with no vascular compression but evident increase in the thickness of the trigeminal-coated arachnoid mater was 6 sides (4.4%).In the 136 cases,neuralgia of 134 cases disappeared after decompression,namely,the curative rate was 98.5% and MVD failed in two cases.The follow-up study for the 112 cases,with the average of 4.3 year,found that neuralgia of 102 cases disappeared completely,of 4 cases,was partially alleviated and of the other 6 cases,recurred or made no progress at all.□Conclusion Compression of the adjacent blood vessels is one of the primary etiological factors for trigeminal neuralgia and microvascular compression is by far the most effective therapy for the treatment of this disease,the efficacy of which depending on the mastery of professional microsurgical anatomy knowledge and microsurgical techniques.The key to enhancing the efficacy and reducing postoperative complications is carefully searching and assuredly isolating all the responsible blood vessels,and protecting the nerves and blood vessels in adjacent areas.