Spinal nerve roots are structurally distinctive: 1. Spinal nerve roots lack the bundle membrane and outer membrane of peripheral nerves, and their axons are surrounded only by a thin root sheath (endoneurium) and cerebrospinal fluid. There are no bundle branches in the spinal nerves, and the amount of collagen in the nerves is five times lower than in the peripheral nerves. The axons of the spinal nerve roots do not have the “Fontana striae” that are found in the axons of the peripheral nerves, and these striae are thought to be able to compensate for the pull of the nerves. 3. The arteriovenous network of spinal nerve roots is not as rich as that of peripheral nerves, and another significant feature of the difference between nerve root blood flow and peripheral nerve blood flow is the lack of vascular communication between nerve roots and peripheral ****. Due to the above characteristics, it is easy to see that the nerve root’s outer nerve membrane is extremely underdeveloped, with no elastic buffering effect and chemical barrier function, and is highly susceptible to external inflammatory attack. The ability to compensate for the pull is also lower than that of the peripheral nerves, which, combined with poor blood circulation, can easily incur mechanical and chemical injury. When local aseptic inflammation occurs, the metabolites cannot be excreted out of the body in time and the absorption of inflammation is affected. If inflammation persists for a long time, it leads to local fibrotic degeneration. Therefore, nerve root injury is extremely common in herniated discs. Anatomical features of the nerve root canal: The nerve root canal is the bony fiber canal through which the nerve roots leave the dura to the outer mouth of the intervertebral foramen, including two parts, namely the lateral saphenous fossa and the intervertebral foramen nerve root canal which extends from it to the front and bottom, wide inside and narrow outside, slightly flattened in front and back, like a funnel with a small mouth facing outward. The L5 nerve channel is almost twice as long as the L1 nerve. The angle between the nerve root and the dural sac decreases from 40 degrees to 22 degrees, which means that the more downward the nerve root is, the more pressure it has in the intervertebral foramen. 2, the outside of the lateral saphenous fossa is the arch root, the posterior wall is the top of the upper articular process, the vertebral plate and the yellow ligament together; the front is the bottom of the posterior and lateral parts of the upper and lower vertebral bodies and the adjacent intervertebral discs together. 3, the upper and lower boundaries of the intervertebral foramen are the posterior upper edge of the vertebral arch, and the top is formed by the ligamentum flavum, which is followed by the articular eminence joint. The intervertebral foramen not only passes through the nerve roots, but also has intervertebral arteries and veins passing through it, as well as the connective **** which protects the blood vessels, while there exists some fibrous compartments connected between the intervertebral disc fibrous ring and the articular eminence joints, dividing the intervertebral foramen into two canals, the upper and the lower. The upper canal passes through the lumbar nerve roots, the intravertebral branch of the lumbar artery and the superior branch of the intervertebral vein; the lower canal passes through the inferior limb of the intervertebral vein. The intervertebral foramen has another fibrous septum in the upper part of the external opening, which is connected to the intervertebral disc fibrous ring and the transverse process and intertransverse process ligament, dividing the external opening into upper and lower foramina, and the lumbar nerve roots pass through the lower foramen. In the upper lumbar vertebrae, the fibrous septum of the foramen is high and thin, but in the lower lumbar vertebrae it is low and thick and membrane-like, which closes most of the foramen. The area of the external foramen and the nerve root appear to be very different, especially in the longitudinal direction compared to the lateral direction, and there appears to be more room for movement. Therefore, the spinal nerve roots are affected by both the lateral saphenous fossa and the intervertebral foramen since they leave the dura to the foramen. The lateral saphenous fossa, although its external, posterior and anterior walls are bony structures, is lined with a soluble and rather large spinal canal. When the lateral saphenous fossa gradually narrows over time, the nerve root itself should have the ability to shift medially (within the spinal canal) and maintain smooth passage. Degeneration of the fibrous septum can prevent the nerve from moving medially (into the spinal canal) and can be compressed by the lateral saphenous fossa. The intervertebral foramen is adjacent to bone on all sides, with little effective space, and the nerve roots are held in place by the fibrous septum. When a disc herniation causes local pathological changes, in the inferior lumbar spine, the nerve roots passing between them are not able to protect themselves from inflammation because of the low and thick fibrous septum that holds the nerve roots in place. In addition, due to the above pathological changes, the fibrous compartment of the intervertebral disc fibrous annulus may develop fibrosis contracture, which may cause the nerves passing through this bony fibrous canal to become compressed and cause symptoms. This shows the clinical value of the special structure of the fibrous compartment in the intervertebral foramen in the symptoms of low back pain caused by lumbar disc herniation. I. Indications: (a) Posterior branch of lumbar spinal nerve entrapment syndrome 1. paravertebral pain, aggravated by rest position, no improvement after rest 2. restricted movement, pain aggravated by changing position 3. no radicular symptoms, may be accompanied by low back pain 4. normal neurological physical examination 5. auxiliary examination is dominated by spinal degeneration, with or without intravertebral canal lesions. (B) Post-herpetic neuralgia. (iii) Post-surgical pain, reflex sympathetic dystrophy, etc. II. Site selection: 1. Hip pain: search for pressure points on the transverse processes of the spine according to the distribution pattern of the posterior lateral branch of the lumbar spinal nerve in the hip. That is, the closer the pain site is to the lateral side of the hip, the higher the position of the pressure point, and the closer it is to the midline position, the lower the position of the pressure point. 2.For pain on the lumbosacral midline side, look for pressure points on the transverse processes of the three upper vertebrae. 3.Pain in the middle and lateral part of the iliac spine, look for pressure points on the transverse processes above L2 on the diseased side. 4, pain at the sacroiliac joint, find pressure points on the L5 transverse process. There are many treatment methods for posterior branch back pain, but they are all based on accurate localization. The posterior branch is the most easily damaged site anatomically and biomechanically, and only by blocking the conduction of the posterior branch at this site can the treatment purpose be achieved. Among the posterior branches of lumbar 1-4, the posterior branch of lumbar 2 is the most frequent site, and special attention should be paid to its positioning. The posterior branch of the lumbar spinal nerve is involved in the medial and lateral branches, or the posterior branch trunk itself is irritated. The posterior spinal nerve trunk is about 0.5 to 1 cm long, and the trunk of the posterior spinal nerve trunk of L1 to 3 spinal nerves is about 1.5 cm lateral to the intervertebral foramen, and the trunk of the posterior spinal nerve trunk of L1 to 3 spinal nerves is about 2 cm lateral to the intervertebral foramen from the division of the spinal nerve root. Body surface localization of the trunk: the upper edge of the transverse process of the inferior vertebral body, the lateral aspect of the superior articular process, and the dorsal superficial aspect of the intervertebral foramen. (1) The patient may be placed in a lateral or prone position. (2) The spinous processes of the lumbar spine are relatively flat and not significantly tilted, and the spinous processes are essentially at the same level as the co-located intervertebral foramina. Precise measurement of isometric lumbar frontal and lateral X-rays is required to determine the body surface positioning of the posterior branching trunk. (3) The general puncture point can be set at 3 to 3.5 cm lateral to the midpoint of the lumbar spinous process gap. (4) The skin is routinely disinfected, and a No. 7, 10-cm-long puncture needle with a core is punctured vertically, and the needle is slowly advanced straight to the dorsal surface of the transverse process at the proposed blocking stage. Usually the distance from the skin to the transverse process is about 3 to 4 cm. After the tip of the needle reaches the transverse process, the needle can be withdrawn a little to improve the needle direction and continue to enter the needle 25° upward and 20° inward to find the upper edge of the transverse process root. (5) Puncture response in place: patients often complain of mild radiating pain in the corresponding posterior branch area, at which point the puncture needle tip should be located at the upper edge of the transverse process root of the inferior vertebral body and lateral to the superior articular process of the intended nerve block phase. (6) After retraction without blood and cerebrospinal fluid, 8-10 ml of anti-inflammatory and analgesic solution can be injected slowly. (7) Caution: When puncturing and injecting drugs, the bevel of the puncture needle tip should be directed inward and not outward, which can reduce neurovascular injury and facilitate the diffusion of drugs to the posterior branch trunk. Note: Once the tip of the needle reaches the upper edge of the transverse process root, stop the needle. If the needle tip slips past the upper edge of the transverse process and continues to enter the needle for more than 1 to 1.5 cm, a block of the spinal nerve root (including the anterior and posterior branches) is formed. If multiple stages of the posterior branch trunk are to be blocked, the same method of puncture can be used. 2.Lumbar nerve root block under C-arm machine (1) Prone position method ①Patient is placed in prone position with a pillow on the lower abdomen so that the back is parallel to the X-ray operating table surface. ②Adjust the X-ray tube ball so that the end plates above and below the L5 vertebral body become parallel. ③The puncture point was chosen to be 4 cm lateral to the median collateral opening (near the tip of the transverse process) at the level of the inferior border of the vertebral arch. The skin is disinfected, the skin is penetrated with a No. 7 9-cm long puncture needle for local anesthesia, and the needle is retracted slightly under C-arm X-ray surveillance deep to the inferior border of the basal part of the transverse process, then the L5 nerve is targeted around the nerve root outside the spinal canal, and the nerve is driven caudally into the transverse process. When the nerve was entered, there was a sudden body movement of electrically discharged pain. ⑤ Inject 1 ml of contrast agent, and inject 2 ml of local anesthetic (containing dexamethasone 4 mg) into the film. (6) Quiet rest for 1h after the block before walking around. (2) oblique position method ① take the affected side on the upper oblique position, the affected side of the lower abdomen pillow, the healthy side of the lower limbs gently extended, the affected side (above) of the lower limbs gently bent semi-prone position, the angle with the X-ray table is 30 ~ 45 ° ② in the X-ray fluoroscopy into the target vertebral body under a caudal side of the vertebral body of the lateral edge of the supra-articular synapse accounted for 1/3 to 1/4 of the end plate of the whole semi-prone position, generally in cases of large supra-articular synapse hypertrophy accounted for the end plate The lateral 1/3 of the endplate is appropriate, and the lateral 1/4 of the case with small deformation is better. ③After determining the angle of the oblique position, the vertebral body endplate (lower edge of the vertebral body) is straightened. ④The puncture point is set at the lower part of the “dog’s jaw”, slightly lateral to the supra-articular process immediately below the arch, and on the cephalad side of the vertebral body endplate. ⑤Caution: The penetrating needle should be inserted in a direction consistent with the ball axis of the X-ray tube to reach the nerve root. If it does not reach the nerve root, change the direction of penetration slightly to the ventral or dorsal side, but do not change the direction of penetration to the caudal side, otherwise it will penetrate the intervertebral disc. In addition, if the tip of the needle is inserted in the direction of the intervertebral foramen, there may be a risk of entering the subarachnoid space, which should be noted. The procedure for injecting contrast and drugs is the same. However, it is difficult to determine the angle of the oblique position, and the patient should maintain the adjusted position, so a good pillow should be used. (6) Generally, the posterior branch of L5 is first, and the needle is inserted vertically in the anterior-posterior position by walking along the sacral wing and the superior articular process of S1. The posterior medial branch of L234 is selected for oblique puncture at an angle of 15-20 degrees on the affected side, and the target point is the root of the transverse process and the lateral edge of the small joint. Depth: The tip of the needle should not exceed the midpoint of the articular surface in the lateral view. The oblique film shows the tip of the L5 needle just above the sacral wing and the formation of the superior articular process of S1, because L5 blocks not the true posterior medial branch but the posterior branch. The lateral film is adjusted for depth and exceeds the midpoint of the articular surface, indicating that the needle tip position is too deep, as long as it is gently moved back, it is best to block both up and down for good results. 3. Operation of radiofrequency posterior spinal nerve block (1) The patient is placed in prone position with a pillow under the abdomen, the spinous process is palpated and marked, and the spinous process is opened about 2 cm laterally as the puncture point, and the towel is routinely disinfected and spread. (2) Use a lumbar puncture needle or a radiofrequency puncture needle to slowly enter the skin vertically from the entry point to reach the transverse process bone surface, and then slowly adjust the position of the needle tip until it is as close as possible to the root of the transverse process. (3) This anatomic positioning is more accurate if the needle tip is confirmed to be at the root of the transverse process in both orthogonal and oblique lateral positions when positioned under x-ray. (4) For more precise localization, it is also possible to connect radiofrequency electrodes and use motor and sensory tests. Generally speaking, if there is significant muscle throbbing or pain in the area innervated by the posterior spinal nerve branch within 0.5 V, it proves that the needle tip is very close to the posterior spinal nerve branch here, and there is no blood or cerebrospinal fluid in the retraction, then 3-5 ml of local anesthetic can be injected. (5) Generally, the block of the posterior spinal nerve branch should be about 2-3 up and down at the same time, because The branches of the posterior spinal nerve have the characteristic of cross distribution. (4) Complications There are generally no serious complications, and possible complications such as nerve injury may occur, so explain clearly to the patient beforehand. 1.Subarachnoid block, subdural block, epidural up block: subarachnoid block sometimes occurs when the needle enters the spinal canal through the intervertebral foramen. If blood pressure drops, fluids and oxygen should be administered, and if necessary, antihypertensive drugs should be injected. Subarachnoid injection with steroids should not occur. 2. Nerve injury Repeated puncture of the nerve has the possibility of occurring. Sensation is lost and muscle strength is reduced over a period of time. If the pain does not appear even after several punctures, the direction of X-ray fluoroscopy should be adjusted and frequent punctures should be avoided if possible. In addition, nerve damage may occur even if strong discharge pain is present, and the operation should be rescheduled in this case. For patients with diabetes mellitus, the hormones contained in the medication used for nerve root block may cause a rise in blood glucose within a few hours of injection, and may lead to hyperglycemic episodes, so it is necessary to reduce the amount of hormones used for diabetic patients or to check blood glucose. 4. Infection Except for patients with poorly controlled loose urine, infection generally does not occur when routine operations are adequately sterilized. If there are signs of infection at the puncture needle site, change to another site for the procedure. 5, bleeding Usual operation does not occur bleeding, but bleeding may occur in patients who are taking anticoagulants, when nerve root hematoma causes nerve injury, and detailed consultation should be made. 6.Pain The symptoms turn mild after nerve root block, but after several hours, it is more painful than before the block, which is due to mild injury to the nerve root, and usually occurs when the release pain is strong, and the patient is informed before the operation. V. Duration of treatment Once a week, 2 to 3 times as a course of treatment.