The Effect of Microvascular Decompression in Trigeminal Neuralgia and Hemifacial Spasm

ABSTRACT

OBJECTIVE: Microvascular decompression(MVD) is an effective technique for the patients who have trigeminal neuralgia(TN) and hemifacial spasm(HS). But, the failed MVD cases have been reported in long term follow-up studies. We introduce our unique operative technique in MVD and analyze the effect of MVD through our modified operative technique, offending vessels in operative field, operative complications, and failed cases. PATIENTS AND METHODS: A series of 52 patients with intractable TN(32 cases) or HS(20 cases) were treated by MVD. Other 7 cases of TN were excluded because they were proved to have TNs secondary to other pathologies, such as nasopharyngeal carcionoma, trigeminal schwannoma, epidermoid tumors, postherpetic neuralgia. The follow-up time was from 3 months to 4 years. RESULT: All 52 patients were treated by retromastoid suboccipital approach. 28 patients of TN were treated with MVD only, and the other 4 patients, were treated with selective sensory root squeezing(1 case), partial sensory rhizotomy(PSR)(2 cases), and PSR with MVD(1 case). Among 20 patients of HS were treated with MVD, 3 patients were not relieved after first operation but were free of spasm after reoperation within 1 week. The degree of nerve root compression was classified as compression and contact and the final outcome compared each other. We used our uniquely designed horseshoe-shaped teflon ring to decompress the vessel from the nerve. In TN, the most common offending vessel was superior cerebellar artery(59.4%) and the final outcomes were as follows excellent, 87.5%(28 cases) good, 3.1%(1 case) poor, 9.4%(3 cases). In HS, the most common offending vessel was anterior inferior cerebellar artery(55%) and the final outcomes were as follows excellent, 85%(17 cases) good, 5%(1 case) poor, 10%(2 cases). CONCLUSION: In compressed group, the cure rate was 100%. However, in contact group the cure rate were 81.3% in TN and 75% in HS. RESULT: From the review of the literatures in failed MVD, the etiologies most commonly reported were inadequate decompression, new vessel compression, adhesion and lysis of prosthesis. Our specially designed horseshoe-shaped teflon ring has some advantages to prevent recurrence of symptom by dislodging or slippage of prosthesis or recompression by other vessels. The overall result of our unique MVD was excellent in patients with TN(87.5%) and HS(85%).