Abstract】Objective: To introduce the treatment of lumbar disc herniation with low-temperature plasma nucleus pulposus ablation and to explore the clinical application value of low-temperature plasma. METHODS: One hundred and sixty patients aged 16 to 82 years with lumbar disc herniation diagnosed by MRI and clinical manifestations were treated with percutaneous plasma nucleus pulposus ablation, and their efficacy was observed and analyzed using visual analog scoring (VAS) and Macnab scoring. RESULTS: All patients in the group were followed up from 3 months to 18 months, with an average of 10 months. 160 patients showed different degrees of symptom improvement, with an overall effective rate of 86.25%. The mean preoperative VAS score was (6.11 ± 0.32) and the mean postoperative VAS score was (1.71 ± 0.52) from 3 months to 18 months of follow-up. According to the modified Macnab efficacy assessment criteria, the treatment effect was excellent in 105 cases, good in 15 cases, acceptable in 18 cases, and poor in 22 cases, with an effective rate of 86.25%. None of the cases had serious complications. Conclusion: Under strict control of its indications, plasma nucleus pulposus ablation is an effective minimally invasive interventional procedure for the treatment of lumbar disc herniation with the characteristics of simple operation, safety, small trauma and excellent recent efficacy. Key words】myeloablation; lumbar disc herniation; minimally invasive Lumbar disc herniation is a disease in which the nucleus pulposus protrudes from the fissure due to degenerative changes of the intervertebral disc or rupture of the intervertebral disc due to trauma, and the spinal nerve root is irritated or compressed, followed by various symptoms and signs. Lumbar disc herniation is a common disease that is now facing a younger age. The traditional treatment is disc removal, which is an open surgery. Disc removal surgery is very traumatic and often results in a series of complications such as dural sac injury, nerve root injury or discitis, vascular injury, cerebrospinal fluid leakage, postoperative back pain, high risk and high cost. In recent years, disc decompression is considered a reliable and safe treatment for herniated discs, and low-temperature plasma nucleus pulposus ablation is a type of disc decompression. 10 years ago, this technique was applied to perform nucleoplasty for cervical disc herniation, and satisfactory results were obtained. The procedure is more suitable for patients with discogenic, spinal or neurogenic lumbar disc herniation who have poor results with conservative treatment and whose indications for surgery are not obvious or who are less willing to undergo surgery. One hundred and sixty patients aged 16 to 82 years with lumbar disc herniation treated with nucleus pulposus cryoablation from April 2010 to August 2011 were followed up and observed, and clinically satisfactory results were initially achieved, as reported below. Object and method 1, bed data, the group of 160 patients, 101 male, 59 female; age 16 to 82 years old, average 45 years old; disease duration of 3 months to 10 years; average 36 months. Those with poor results after three months of conservative treatment were included in this clinical study. 2.Operative instruments, American ArthroCare 2002 tissue vaporizer, C-arm X-ray machine, puncture needle. 3, surgical steps, surgical needle approach and puncture access: ① the patient is lying on the C-arm X-ray machine or CT machine, our hospital is C-arm X-ray machine, the patient’s affected side is on the top, the healthy side is on the bottom; ② C-arm X-ray machine fluoroscopy to locate the patient’s lesion of the intervertebral space, mark the needle point (8-10 cm above the affected side of the lumbar spinous process, the position parallel to the disc is the needle point; if L5-S1 (the highest point of the iliac crest is taken to be 6-8 cm away from the midline), and the towel is routinely disinfected; (3) 2% lidocaine 5 ml is used to locally infiltrate the puncture point, fascia, ligaments and intervertebral joints with local anesthesia (it is strictly forbidden to inject anesthetic in the intervertebral foramen near the nerve roots to avoid damage to the nerve roots); (4) the puncture needle is tilted at an angle of 45° to the lumbar dorsal plane, and the direction of the needle tip is adjusted to be parallel to the intervertebral disc space under fluoroscopy from the needle entry point. The tip of the puncture needle is located in the center of the upper and lower vertebral body, and the depth reaches the middle and posterior 1/3 of the intervertebral disc (lateral position), with the center slightly to the affected side (anterior-posterior position); if the puncture direction of L5-S1 is 45°-60° angle to the coronal plane and 35°-45° angle to the sagittal plane, the puncture needle is punctured obliquely to the sacrococcygeal region. After successful puncture, the puncture needle core is withdrawn and a special cryoablation tip connected to the ablation mainframe is placed under the guidance of the C-arm X-ray machine. Determine the exact position of the tip (about 3 mm from the posterior edge of the intervertebral disc), set the energy level to 3, and step on the thermal coagulation button for 0.5 to 1 second, if there are obvious irritation symptoms, stop immediately and reposition the tip. If there is no obvious irritation, continue to press the ablation button for 10-15 seconds, while slowly rotating the tip at a uniform speed of 360° for low-temperature plasma vaporization and ablation, and perform vaporization and thermal coagulation in the counterclockwise direction. Then the knife head was pulled out 3 mm together with the trocar needle and retreated to the center of this intervertebral disc and ablated once again as above. The patient is asked for autonomic sensation during and at the end of the procedure, and a second disc ablation can be performed if needed. After rotating out the tip, the puncture needle is withdrawn, the field is cleaned and disinfected, and a dressing is applied. 4.Post-operative precautions and care After the operation, wear a lumbar girth for four weeks, and take antibiotics routinely for one day (dexamethasone 50mg/d for three days if the pain is severe). Take care of yourself, sit as little as possible within 1 week, rest more in bed, gradually increase the amount of activity. In case of recurrent symptoms, anti-inflammatory and analgesic non-steroidal drugs and local physiotherapy were given. If the symptoms do not improve after 6 months of observation, and CT or MRI review shows no significant regression of the intervertebral disc, a second cryoplasty or traditional open surgery treatment can be considered. Efficacy and evaluation 1. Efficacy evaluation criteria ① Before surgery, 3 days after surgery and three months after surgery were used to score pain visual analog score (VAS): 0 indicates no pain, 10 indicates the most pain; 1 to 3 mild pain, 4 to 6 moderate pain, 7 to 10 moderate pain. ②Efficacy evaluation was performed by the modified Macnab scale at 3 days and 3 months after surgery, respectively, and the main judgment criteria were based on the improvement of clinical symptoms. Excellent: pain disappeared, no activity dysfunction, resumed normal work and activity; Good: pain disappeared, able to engage in light work; OK: symptoms improved, still have pain, unable to work; Poor: nerve compression performance, need to perform surgery. The results were recorded at the postoperative and follow-up periods, and the excellent rate of efficacy was counted. Statistical methods Data were processed according to statistical criteria; mean ± standard deviation, using statistical correlation software, and tested by paired t-test for before and after control, and P < 0.05 was considered significant. 2, The VAS pain score was (2.40 ± 0.87) at three days after treatment, and the mean VAS score was (1.71 ± 0.52) from 3 months to 18 months after surgery and (6.11 ± 0.32) before treatment, which was significantly lower after surgery compared with the preoperative period. the Macnab score efficacy rating at 3 days after surgery was excellent in 108 cases, good in 22 cases, acceptable in 20 cases and poor in 10 cases. The excellent rate was 81.25%, the effective rate was 93.75%, and the postoperative follow-up was from 3 months to 18 months. 105 cases had excellent treatment effect, 15 cases had good treatment effect, 18 cases had good treatment effect, 22 cases had poor treatment effect, and the effective rate was 86.25%. Discussion 1, the mechanism of disc herniation The lumbar intervertebral disc is composed of cartilage endplates, fibrous rings and the nucleus pulposus, of which the main components of the nucleus pulposus are collagen and proteoglycans, while the nutrients of the intervertebral disc cells depend on the periphery of the fibrous rings and the vascular supply in the vertebral body. When the intervertebral disc degenerates, the pressure inside the disc can reach about 24.07kpa, which seriously affects the blood supply from the annulus fibrosus to the central part of the disc, making the nutrition of the disc cells and matrix interrupted, followed by dehydration and fragmentation of the nucleus pulposus, while the tissue is dehydrated and fragmented, thus forming a fissure, which becomes a channel for the protrusion of the nucleus pulposus. The nucleus pulposus protrudes posteriorly to compress the spinal cord and nerves. The compression of the nerve root by the herniated disc and the consequent inflammatory reaction such as edema and exudation of the nerve root are the main reasons for the main clinical symptoms such as numbness and pain in the back and legs. Therefore, lifting the compression, removing the pain-causing medium around the nerve root or improving local microcirculation becomes the key to the treatment of lumbar disc herniation. 2.Theoretical basis of temperature plasma nucleus pulposus ablation Low temperature plasma radiofrequency nucleus pulposus ablation is a combination of tissue ablation and radiofrequency thermal coagulation, through the ablation and vaporization of the nucleus pulposus tissue of the intervertebral disc, so as to reduce the pressure in the intervertebral disc and play a role in relieving pain. The main principle is that the application of 100 kHz radiofrequency causes ions (potassium, sodium, etc.) in the tissue to form plasma, and accelerates the plasma, which breaks the peptide bonds in the nucleus pulposus tissue to form elemental molecules and low molecular gases (oxygen, hydrogen, carbon dioxide), which escape through the puncture channels, thereby relieving the pressure on the dura and nerve roots to achieve the purpose of treatment. This is why radiofrequency is also called plasma knife. The plasma knife head reaches the target disc nucleus pulposus tissue through the guidance of the puncture needle, which allows the nucleus pulposus to achieve decompression and decompression, a very small pressure reduction, which will significantly reduce the irritation of the lesion on the nerve root or nerve endings, thus relieving the symptoms also significantly. In addition, some of the intramedullary tissue is removed and the remodeling of the intradiscal nucleus pulposus is completed; at the same time, radiofrequency thermal coagulation causes the collagen of the disc nucleus pulposus to contract and solidify. Compared with other types of decompression surgery, low-temperature plasma nucleus pulposus ablation is characterized by simple operation (C-arm X-ray or CT machine guided puncture under local anesthesia); relatively small trauma (the diameter of the puncture hole is only 1 mm); safety (the instrument only generates a temperature of 40°C during operation and about 70°C when heated, with a temperature range of 40°C to 70°C, with little heat penetration and tissue (necrotic, only to the surrounding tissue within 2 mm); low-temperature plasma nucleus pulposus ablation only interrupts the molecular structure of the tissue and only changes the biochemical state of the disc, not the direct thermal degeneration of the disc. In cadaveric studies, it has been found that myeloablation decompresses the nucleus pulposus but does not cause necrosis, and that tissue vaporization and coagulation are confined to the nucleus pulposus, while the annulus fibrosus, endplate, and vertebral body are not affected, achieving volumetric removal of the disc without significant thermal or structural damage to the surrounding tissue. There is no effect on the stability of the spine. 3.Evidence Low temperature plasma nucleus pulposus ablation is less traumatic, more complete ablation and better efficacy compared with other minimally invasive procedures. Its temperature is lower and will not cause thermal damage to other surrounding tissues under proper operation. Conservative treatment within 3 months of first onset is preferred. In case of recurrence, it is the target of treatment. Good indications are as follows: (i) low back pain, with leg pain as the most important one, and positive straight leg raising test; (ii) manifestation of nerve root injury, such as abnormal superficial sensation, decreased muscle strength, abnormal reflexes, etc.; (iii) herniated or limited bulging disc confirmed by CT or MRI, and clinical symptoms and signs are consistent with the imaging diagnosis. Conservative treatment for 2 to 3 months is not effective in accordance with the above conditions. 4, contraindications ① bleeding body with serious cardiovascular and cerebrovascular diseases, pregnant women and patients with mental disorders; ② calcification or ossification of the herniated disc; ③ significant narrowing of the intervertebral disc space or spinal canal, slipped vertebral body; ④ obvious disc prolapse or free into the spinal canal; history of surgery (the same level) or chemical myelolysis; ⑤ with severe ankylosing spondylitis, rheumatoid arthritis; ⑥ intervertebral disc infection (7) those with spinal cord compression degeneration and cone bundle sign. (8) disc height reduction by 2/3 or severe degeneration or vacuum. 5, hair disease Overall, cryogenic plasma nucleus pulposus ablation is a safe and minimally invasive surgery. Only a few scholars have reported cases of postoperative bacterial discitis and dural fibrosis. If the puncture process causes transient radiating pain in the lower extremity, the needle needs to be slightly withdrawn and the direction and angle of needle entry changed, and the operation can be continued. A few people reported intraoperative tip fracture, but the fracture rate is not high. Consider the following factors: (1) the diameter of the cervical tip is thin about 1mm, which is not strong enough; (2) it is related to the incorrect intraoperative puncture route, which reduces the strength of repeated punctures; (3) the frequent swallowing action of the patient during the operation, which has a squeezing effect on the tip; (4) the tip is used several times. 6, matters of interest ① MRI shows severe disc degeneration cases should be excluded. Although the disc height is still normal, the ablation effect is not very satisfactory, which may be related to the decrease of disc water and serious degeneration in such patients, thus reducing the ablation effect of low-temperature plasma. In addition to preoperative instructions, good communication with the patient, and intraoperative cooperation between the operator and the patient are necessary to complete the surgery. ③The solid anatomical knowledge and standardized operation of the operator are the keys to improve the efficacy and reduce complications. Cryogenic plasma nucleus ablation is performed under local anesthesia, and the operation is fast, safe and effective. Compared with other minimally invasive surgeries, this procedure has a small puncture hole, and the puncture channel is basically bloodless, compared with percutaneous puncture and aspiration, the channel is significantly smaller, and the incision and aspiration are highly injurious, requiring a week of bed rest after surgery; compared with laser treatment, the local temperature of this procedure is low (about 40℃～70℃), with little thermal damage and mild pain, while the local temperature of laser is high (about 300℃～600℃), with great thermal damage and significant pain. The laser has high local temperature (about 300℃～600℃), high thermal damage and significant pain. The whole procedure of low-temperature plasma nucleus ablation only takes about 5-10 min, and there are no complications such as spinal cord, nerve and blood vessel damage after the operation.