1.Anesthesia Intravenous compound general anesthesia can make the patient completely relaxed and ensure the safety of surgery. Vital signs should be as stable as possible during induction of anesthesia. 2.Surgical position The patient is placed in lateral position with the affected side upward, the upper body is elevated about 15 degrees, and the head is naturally lowered about 15 degrees, so that the mastoid process is located at the highest level of the head, and at the same time, it should be 5-10 cm above the level of the atrium, so that the intracranial venous sinus can maintain a lower pressure, which helps to avoid the rupture of the venous wall when the rock vein is treated by electrocoagulation. The affected shoulder is pulled towards the end of the bed with a shoulder strap to reduce the obstruction of the operative field by the shoulder. However, care must be taken not to overstretch the brachial plexus nerve causing injury. 3.Surgical incision The affected mastoid notch is used as the upper quarter point of the incision, and an oblique incision of about 4 cm in length is chosen according to the length of the neck and the thickness of the neck muscle. After local infiltration with epinephrine saline (1:200,000), the skin was incised and the skin edge was hemostatic with bipolar electrocoagulation. The occipital muscles are incised with an electric knife up to the skull, and the muscles are peeled and drawn away from the occipital bone. The posterior mastoid process is often connected to the sigmoid sinus by 1-2 conduit holes, which are electrocoagulated, and the bone holes are closed with bone wax. 4.Bone window Drill a hole in the occipital bone at the posterior edge of the mastoid process and enlarge it into an oblique oval bone window with a diameter of 2-2.5 cm with the upper end revealing the lower edge of the transverse sinus and the outer side revealing the posterior edge of the sigmoid sinus, and the angle of intersection of the venous sinuses is revealed at the angle of entrapment. In patients with large mastoid air spaces, it is often necessary to bite open the mastoid air space to obtain a satisfactory exposure, paying attention to carefully closing the mastoid air space with bone wax to avoid postoperative cerebrospinal fluid leakage. Before biting off the skull, the dura mater should be freed well and the dura mater and venous sinuses should not be injured. The guiding veins should be properly electrocoagulated to stop bleeding when encountered. The edge of the bone window should be closed with bone wax to stop bleeding, and the bleeding of the dura and sinus edge should be avoided by electrocoagulation and cauterization as much as possible, and gelatin sponge and cotton pad can be used to stop bleeding. 5.Dural incision Make an inverted “T”-shaped incision at the center of the intersection of the transverse and sigmoid sinuses, and suspend one needle for each of the two dura mater. The edges of the dural incision are protected with a wet cotton sheet. 6.Release cerebrospinal fluid Under direct microscopic view, the cerebellar hemispheres are gently pulled with a brain press in the direction of the mastoid tip, and the cerebrospinal fluid is slowly released until the arachnoid at the auditory nerve is fully exposed. Displacement of the cerebellum can cause the tiny arteries or veins between the cerebellum and the dura to be pulled off, and careful exploration is required to stop the bleeding. 7. Reveal the trigeminal nerve Use microscissors to cut the arachnoid membrane on the surface of the cerebellum at the auditory nerve, and gradually reveal and cut the arachnoid membrane around the trigeminal nerve root along the angle of intersection between the cerebellar curtain and the temporal bone rock toward the upper cerebellum until the entire trigeminal nerve is fully revealed. The arachnoid membrane covering the trigeminal nerve roots must be widely dissected to expose this area. Care must be taken to identify the tiny vessels and nerves beneath it to avoid injury. If there is bleeding in the exposure, the pontine vein between the upper cerebellum and the canopy may be torn, and this area should be explored to control the bleeding before continuing deeper. The supratentorial vein is a group of veins that drain the lateral cerebellum and pontine brain. It is highly variable and usually converges into one or two short thick trunks that merge into a Y-shape when approaching the dural sinus, penetrate the arachnoid and merge into the supratentorial sinus. If the superior petrosal vein obstructs exposure of the trigeminal nerve, it may be necessary to free cut the arachnoid membrane around the petrosal vein and then electrocoagulate and cut it. The trigeminal nerve root must be exposed and explored before dissection because the pontocerebral branch of the rock vein often crosses the angle between the trigeminal root and the pontocerebrum and is the vein that most often forms venous compression of the trigeminal nerve; dissection of the rock vein first may cause the compression vein to disappear, leading to false negative findings. In principle, as long as the available space can satisfactorily reveal the trigeminal nerve roots, the possibility of cerebellar venous infarction can be reduced by not cutting the rock vein and its branches as much or as little as possible and by preserving the reflux of the rock vein. When cutting off the rock vein by electrocoagulation, the bipolar electrocoagulation power should be low, and the vein should be cut off after repeated electrocoagulation to burn the vein completely, and an extra section of the burned vein should be left at one end of the supratentorial sinus. 9.Handling of the responsible vessel After dealing with the rock vein, probe along the back of the rock bone under the canopy, anteriorly and medially, and enter in front of the facial and auditory nerves, medially or laterally in the rock vein. Take care not to disturb the facial and auditory nerves and their surrounding arachnoid membrane during the exploration Jannetta and Rhoton had carefully studied the vascular distribution and variants near the trigeminal nerve root, and pointed out that the superior cerebellar artery and its branches, the pontocerebral branch of the basilar artery, the tortuous basilar artery itself, and the anterior inferior cerebellar artery could all form compression of the trigeminal nerve root into the pontocerebral region, with the compression of the branches of the superior cerebellar artery being the most The branch of the superior cerebellar artery is the most common. The vessels next to the distal segment of the trigeminal nerve are not the responsible vessels, because the myelin sheath formed by the peripheral nerve Shewan’s cells has a strong resistance to pressure, and the impact of the vessels usually does not lead to serious demyelination. Most commonly, the superior cerebellar artery forms a collaterally tortuous protrusion anterior to the nerve, which then forms a compression at the dorsal nerve root of the trigeminal nerve into the pontine brain. Arterial compression can usually form a distinct indentation at the root of the trigeminal nerve or anterior to the pontine brain. The more pronounced the indentation, the more pronounced the surgical result. It is important to open the arachnoid widely intraoperatively and to thoroughly examine the site of the trigeminal nerve root into the pontine brain, as there may be more than one responsible vessel. Extensive opening of the arachnoid membrane anterior to the nerve root is necessary to truly free and release the responsible vessel compressing the nerve, so that the Teflon cotton, which pads the vessel, has sufficient space and does not remain tightly attached to the nerve root to continue mediating the impact of the arterial pulsation or form adhesions with the nerve root, leading to pain recurrence. After the responsible artery is sufficiently free, the artery is padded away from the trigeminal nerve root with Teflon cotton. The padded cotton was positioned as far away from the nerve root as possible, and the padded vascular collaterals should not be folded into dead space. The small trophoblastic vessels on the nerve root and pontine surface are not relevant to trigeminal neuralgia and must not be damaged. The veins immediately on the pontocerebral surface of the trigeminal nerve roots may also form compression on the nerve and need to be carefully freed gently with a nerve stripper and then electrocoagulated and clipped. Only by clipping the constricted and occluded venous strips after electrocoagulation can the purpose of decompression be truly achieved. If, after careful examination, no vascular compression of the trigeminal nerve root is found, a selective trigeminal nerve root dissection is required, in which the posterior lateral 1/2 of the trigeminal nerve root is cut. Patients with partial cut of the sensory root of the trigeminal nerve will be left with hypoesthesia or loss of sensation in the lower 2/3 of the ipsilateral lateral surface and half of the anterior tongue. At this stage in China, the reason for vascular decompression surgery with partial trigeminal nerve sensory root severance is for those who are not suitable for secondary surgery due to economic and physical condition. 10.Closing the incision After the trigeminal nerve is treated and the bleeding is carefully stopped, the operative field is flushed with warm saline containing corticosteroids and vasodilators, and the operative cavity is filled to reduce postoperative intracranial pneumatization. After the items were counted correctly, a collagen sponge was padded inside the dural incision, the dural incision was tightly sutured, and the outside was then cemented with a piece of gum metan white sponge with biogel. The bone debris collected at the time of craniotomy was sterilized and cleaned and backfilled with the bone window, which was shaped and fixed with bioadhesive. The incision is not placed with drainage, and the muscle and subcutaneous are sutured in layers. The skin incision is cemented with bio-quick drying glue.