Microvascular decompression surgery MVD surgery aims to move the compressed artery or vein away from the nerve. For cases of trigeminal neuralgia, a posterior sigmoid sinus opening is used with the aim of exposing the cerebral pool segment of the trigeminal nerve, which emanates from the cerebral bridge and enters the Meckel’s cavity. The patient may be placed in prone, lateral, supine cephalolateral, or sitting position, depending on the experience or preference of the operator. A short straight or curved incision behind the mastoid process is used to make a small bone window opening (approximately 2.5 cm in diameter) within the transverse sigmoid sinus intersection angle. In order to reduce strain and to better expose the nerves, cerebrospinal fluid needs to be aspirated from the medullary pool of the cerebellum, which can relax the cerebellar hemispheres; there is a risk of serious complications (e.g., venous obstruction, cerebrovascular accident, etc.) if excessive strain is applied. In addition, auditory evoked potential monitoring is useful for early detection of signs of excessive strain on the cerebellum or brainstem. Ni Bing, Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University Once the nerve has been exposed, the responsible vessel is usually obvious. Once the vessel is located, the nerve needs to be carefully separated from the vessel. This operation requires gentle, blunt separation and occasionally requires microscissors to sharply separate the hyperplastic arachnoid adhesion zone. A small pad of Teflon cotton is placed between the vascular nerve to prevent spontaneous readhesion of the neurovascular. In some rare cases, the responsible vessel is long and tortuous, and some operators will separate the two by wrapping the vessel with a perforated aneurysm clip and suturing it to the dura. If no compressing vessel is found, some operators dissociate the thickened arachnoid around the nerve, place a small piece of Teflon cotton between the nerve and the brainstem, and then gently squeeze the nerve with the tip of a forceps with double-strike electrocoagulation, causing a slight neurological deficit. At least one group of studies has suggested that rigid neuroendoscopy (in their case, tilted at 30°) improves the detection rate of compressed vessels. Overall, MVD has a high success rate. In one definitive study, close to 3/4 of patients remained pain-free and off medication after 5 years of MVD treatment, and 2/3 of these patients remained pain-free without medication at follow-up to 20 years. Other results reported on long-term pain disappearance are similar. Although there is an initial inpatient neurosurgical expense with MVD, considering these long-term benefits, the procedure remains the therapy with the highest cost/benefit ratio.The results of MVD compared with a percutaneous approach to trigeminal neuralgia are shown in Table 103-1.Several factors are considered to predict a good outcome, namely immediate postoperative pain relief, male, arterial rather than venous compression (in the REZ), and preoperative history relatively short (<8 years). In addition, as with other complex neurosurgical operations, the safety of MVD is highly dependent on the experience of the operator (and the provider performing the procedure); neurological complications, including stroke, postoperative hemorrhage, facial palsy, and cerebrospinal fluid leakage, have a higher incidence for physicians with fewer surgical cases.