Microvascular decompression for trigeminal neuralgia refers to the application of microsurgical techniques to remove the blood vessels compressing the nerve and place decompression material between the nerve and the blood vessels to achieve the disappearance of postoperative facial pain. This decompressive surgery does not cut the nerve, preserves the integrity and physiological function of the trigeminal nerve, and preserves facial sensation after surgery. Therefore, it is said to be a more ideal treatment method for removing the cause of the disease, and is widely used in China and abroad. The purpose of this paper is to introduce the experience of decompression surgery through surgical treatment of 1014 cases of trigeminal neuralgia with good efficacy, and yet exaggerate the suspicion of flattery, and only introduce a few issues that put forward attention for discussion. Lv Fulin, Department of Neurosurgery, General Hospital of Jinan Military Region
Clinical data
1, of 1014 cases, 527 men, 487 women; age, 26-82 years; duration of disease 0.5-32 years; pain side, 504 on the right side, 439 on the left side; site, Ⅰ branch 75 cases, Ⅱ branch 166 cases, Ⅲ branch 150 cases, Ⅰ-Ⅱ branch 84 cases, Ⅱ-Ⅲ branch 358 cases, Ⅰ-Ⅲ 99 cases, 82 cases of bilateral sex.
2, Surgical method: A small cranial incision was made behind the mastoid process, and the vessels compressing the trigeminal nerve entry area were found in the paramedian area, which were separated, filled with septum and isolated for decompression.
3, Intraoperative findings, such as the indicated Vessels compressing the trigeminal nerve entry area
Vessel
Number of cases
Type of vascular compression
contact
compression
Adhesive encapsulation
penetration
Superior cerebellar artery
767 (75.64)
281
244
234
4
Anterior inferior cerebellar artery
76 (7.50)
30
26
20
Basilar artery
12 (1.18%)
10
2
Arterio-venous malformation
112 (11.05%)
40
37
35
Posterior inferior cerebellar artery
10 (0.99%))
9
3
Vein
37 (3.65%)
21
16
4, postoperative efficacy, among 1014 cases, 979 cases (96.55) had pain relief on the same day after surgery, 5 cases with hearing loss, 6 cases with cerebellar symptoms, 11 cases with recurrence, and 13 cases with facial muscle weakness, mild degree of low group cranial nerve and cerebrospinal night leakage and other symptoms.
Discussion
1. Selection of indications
(1) Those whose pain-relieving effect of long-term medication has been weakened or disappeared, or those who have side effects or allergic reactions to medication and cannot adhere to medication and are willing to receive surgical treatment.
(2) Those who have relapsed with alcoholic peripheral branch closure, avulsion or radiofrequency treatment of semilunar ganglion.
(3) Those with branch I pain or branch I, II or III pain, or bilateral trigeminal neuralgia, who apply this method in one stage or staged surgery.
(4) Trigeminal neuralgia with facial muscle twitching (called painful twitching). Especially in young patients.
(5) Those who have no serious diseases of important organs of the body and are under 70 years old and willing to operate; for those who are over 70 years old and in good general condition, they should also actively and cautiously consider surgical treatment.
2, decompression position: the head position is lateral, the affected side is upward, the head and neck exceed the top of the surgical bed, the head and face are rotated to the healthy side at an angle of 100, the median line of the head (sagittal line) is parallel to the bed surface, so that the head is tilted forward, the chin is about two cross fingers from the sternum, the shoulder is fixed with a bandage to the hip, so that the head, neck and shoulder angle is greater than 900 angles, the head frame is fixed, this head position exposes the nerve roots and also provides maximum space to facilitate This head position exposes the nerve roots and also provides maximum space to facilitate the surgery (Figure 1, a,b).
3. Incision design: The principle of designing the incision is to make a slightly shorter incision for a long and thin head and neck, and a slightly longer incision for a short and thick head and neck, and to set the angle at an oblique angle downward (Figure 2,a,b). Before designing the incision, bony occipital landmarks such as the mastoid process, the external occipital ridge, the superior and inferior lines of the collar, and the bicipital sulcus were determined. Usually, the intersection of the inferior collar line and the bicipital interosseous groove is the connection between the transverse and sigmoid sinuses. There are two types of incisions: (1) oblique incision for the short and thick head and neck type, which is made at an angle of 200~30 0 on the affected side of the mastoid process, two transverse fingers down to the midline. The transverse incision is used for the long and thin head and neck type, in which the two transverse fingers on the affected mastoid are cut parallel to the midline. The length of the incision is 3~5 cm.
4.Bone window: There are two types of bone windows, one is triangular and the other is circular. The drilling site should be chosen from below or below the lateral conduction vessel of the mastoid process, and the hole is generally drilled to enlarge the bone window by ≥ or Ì 2 cm. The top of the bone window is in the connection, and the sinus edge of the dura mater is reached on both sides.
5, dural incision: dural incision can be divided into triangular row or “risk” or flap-shaped 3 kinds of incision. Triangular incision, the top angle points to the connection, the dura is turned over to the base and fixed.
6.Probe the pontocerebellar paramedian area: this area refers to the area between the pontocerebellar paramedian area and the slope, in which there are mainly trigeminal nerve, arteries and veins. The method is to use the lateral superior cerebellar approach, pull the cerebellum to the posterior midline, release the cerebrospinal fluid, and see the rock vein and facial nerve to be protected. At the entrance of the rock vein, 0.5 cm below the anterior both see the trigeminal sensory roots, find the abnormal surrounding vessels in the nerve entry area (at the pontocerebellum), determine the relationship between the vessels and the nerve, and type them. Three points should be noted in the operation: ① the function of the cerebral pressure plate is not only to compress the cerebellum toward the midline, but also to slowly discharge the cerebrospinal night; ② release the cerebral pressure plate or retractor at the right time to reduce the compression or pulling injury to the cerebellum or nerve; ③ do not deal with or damage the rock vein and its branches, still if blocking when the line of sight needs to be dealt with, cut it twice or more with bipolar electrocoagulation to widen the operative field.
7, the relationship between the trigeminal nerve and blood vessels: the trigeminal nerve into the area mainly has the superior cerebellar artery, the anterior inferior cerebellar artery, the vertebral artery and its veins and branches. The relationship between the two is in the form of “ten” cross, oblique cross, a few wrapping twist and penetration. In order to express the basic pathologic and anatomical features of vascular pulsation and cross-wrap on nerve compression, it can be divided into four types: contact, compression, cohesive wrap, and penetration. The criteria for typing: ① contact type, the vessel is in contact with the nerve, but does not compress the nerve; ② compression type, the vessel compresses the nerve root, and there are concave traces of compression; ③ adhesion encirclement type, the vessel and the nerve are encircled together by adhesion tape, and there is nerve displacement and deformation; ④ penetration type: the vessel penetrates and compresses the nerve. The purpose of mastering the typing is to facilitate surgical decision making. The treatment is divided into different categories. For contact or compression type, a small cotton pad can be used to sharply separate and push away the artery and vein wall; for artery and vein or smaller vein, electric vein can be cut to preserve the artery; for adhesion and encirclement type, sharply separate and loosen the adhesion and cut; for penetration type, a longitudinal incision should be made along the long axis of the nerve, and the nerve bundle should be cut to push the penetrating vessel to the curtain side, away from the nerve entry area. Points of attention for vascular treatment: ① electrocautery is strictly prohibited for arteries regardless of thickness and size, and silver clips are clamped to prevent brainstem ischemia; ② the thicker veins should be preserved as much as possible to keep the brainstem blood return flow smooth; ③ the vascular compression of multiple branches should not be missed, and only one of them should be treated, which can still have painful episodes after surgery.
8. Nerve decompression: Nerve decompression refers to the decompression of the trigeminal nerve entry area. It is divided into two types of decompression: isolation or envelope decompression. The nerve decompression refers to the removal of the blood vessels compressing the nerve, and the placement of decompression material in the neurovascular space and wrapping around the nerve to fix it. The nerve is no longer subjected to pulsatile stimulation and the pain can be stopped after surgery. Currently, decompression materials (minus the so-called septum), such as polyester sheets and Teffron cotton felt blocks, are commonly used. If the polyester sheet is autoclaved, it is cut into rectangular blocks of 0.5 x 1.0 cm2 shape and applied. Note that the decompression material should not be folded, loosely tightened and firmly fixed.
9, cranial closure: cranial closure is as important as cranial opening, in addition to routine hemostasis, flushing, cerebellar repositioning, suturing and disinfection. Points to note: ① the dura mater should be sutured with strict honey to ensure no leakage of cerebrospinal fluid; ② because of the lack of collar muscle coverage on the surface of the diastasis interosseous groove, sutured strictly according to the anatomical level, i.e. occipital muscle, muscle membrane, capitellar Jian membrane and scalp 4 layers, must do sutured capitellar tendon membrane, to cover the full length of the incision. ③The defective skull was fixed with metal mesh titanium plate repair.
10.Brainstem evoked potential monitoring: brainstem evoked potential can be detected in time, and the evoked potential caused by pulling or compressing the cerebellum and cranial nerves can be restored to normal range after adjusting the retractor or stopping the surgical operation for a period of time, and then operated. Because long-term pulling or compression can cause irreversible damage to nerves, such as hearing and facial sensory impairment. Therefore, the monitoring of brainstem evoked potentials is an indispensable tool to reduce or avoid surgical complications.
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