Lumbar disc herniation is one of the more common disorders, mainly because the lumbar intervertebral disc parts (nucleus pulposus, fibrous ring and cartilage plate), especially the nucleus pulposus, have different degrees of degenerative changes, under the action of external factors, the fibrous ring of the disc ruptures, and the nucleus pulposus tissue protrudes (or prolapses) from the rupture in the posterior or vertebral canal, resulting in the adjacent spinal nerve roots suffer from irritation or compression, resulting in lumbar pain This results in a series of clinical symptoms, such as numbness and pain in one or both lower limbs. The incidence of lumbar disc herniation is highest in lumbar 4-5 and lumbar 5-sacral 1, accounting for about 95%. (A) Basic etiology 1, degenerative changes of the lumbar intervertebral disc is the basic factor The degeneration of the nucleus pulposus is mainly manifested by the reduction of water content, and can cause small-scale pathological changes such as vertebral joint instability and loosening due to water loss; the degeneration of the fibrous ring is mainly manifested by the reduction of the degree of toughness. 2, injury Long-term repeated external forces cause minor damage, which aggravates the degree of degeneration. 3, weakness of the disc’s own anatomical factors The intervertebral disc gradually lacks blood circulation and poor repair ability after adulthood. On the basis of the action of the above factors, some kind of triggering factor that can lead to a sudden increase in the pressure on the intervertebral disc, i.e., may cause the less elastic nucleus pulposus to pass through the fibrous ring that has become less tough, causing the nucleus pulposus to protrude. 4, genetic factors lumbar disc herniation has been reported to have familial onset, the incidence of this disease in people of color is low. 5, lumbosacral congenital anomalies, including lumbar sacralization, sacral lumbarization, hemivertebral deformity, small joint deformity and asymmetry of joint protrusion. The above factors can cause changes in the stress on the lower lumbar spine, thus constituting an increase in intradiscal pressure and susceptibility to degeneration and injury. (B) Triggering factors On the basis of degenerative disc degeneration, a certain factor that can induce a sudden increase in intervertebral disc pressure can cause nucleus pulposus herniation. Common predisposing factors include increased abdominal pressure, improper lumbar posture, sudden weight bearing, pregnancy, exposure to cold and moisture, etc. From the pathological changes and CT, MRI performance, combined with treatment methods can be made the following types. The nucleus pulposus is confined to the spinal canal due to pressure, but the surface is smooth. Most of this type can be relieved or cured by conservative treatment. 2.Protruding type The fiber ring is completely ruptured, the nucleus pulposus protrudes into the spinal canal, covered only by the posterior longitudinal ligament or a layer of fibrous membrane, the surface is uneven or cauliflower-shaped, often requiring surgical treatment. 3, prolapse free type rupture protruding disc tissue or fragments into the spinal canal or completely free. This type can not only cause nerve root symptoms, but also easily lead to cauda equina symptoms, and non-surgical treatment is often ineffective. 4.Schmorl’s node The nucleus pulposus enters the cancellous bone of the vertebral body through the fissure of the cartilage of the upper and lower end plates, and generally there is only low back pain without nerve root symptoms, and surgery is not required. (C) Clinical symptoms 1. Low back pain is the first symptom in most patients, with an incidence of about 91%. Due to the stimulation of the outer layer of the fibrous ring and the posterior longitudinal ligament by the nucleus pulposus, the lower lumbar induction pain is produced by the sinus nerve, and sometimes it can be accompanied by hip pain. 2. Lower limb radiating pain Although high lumbar disc herniation (lumbar 2 to 3, lumbar 3 to 4) can cause femoral neuralgia, it is rare clinically, less than 5%. The vast majority of patients are herniated from lumbar 4 to 5 and lumbar 5 to sacral 1 gap, which manifests as sciatica. Typical sciatica is radiating pain from the lower lumbar region to the buttocks, posterior thighs, and lateral calves up to the feet, and the pain increases in response to increased abdominal pressure such as sneezing and coughing. The radiating pain is mostly on one side of the limb, and only a very small number of people with central or paracentral herniated nucleus pulposus show symptoms in both lower limbs. There are three causes of sciatica: (1) chemical inflammation of the nerve root due to chemical stimulation and autoimmune reaction from the ruptured disc; (2) the herniated nucleus pulposus compresses or stretches the nerve root with inflammation, blocking its venous return and further aggravating edema, making it more sensitive to pain; (3) ischemia of the compressed nerve root. The above three factors are interrelated and are aggravating factors for each other. 3. Cauda equina symptoms The protruding nucleus pulposus or prolapsed, free disc tissue compresses the cauda equina nerve, which mainly manifests as obstruction of bowel movement and urination, abnormal perineum and perianal sensation. In severe cases, symptoms such as loss of control of urination and defecation and incomplete paralysis of both lower limbs may occur, which are rare in clinical practice. (D) Signs of lumbar disc herniation 1. General signs (1) Lumbar lordosis is a postural compensatory deformity to reduce pain. Depending on the relationship between the site of the herniated nucleus pulposus and the nerve root, the spine is curved to the healthy side or to the affected side. If the site of the herniated nucleus pulposus is located on the medial side of the spinal nerve root, the lumbar spine bends to the affected side because the spine bends to the affected side to reduce the tension of the spinal nerve root; conversely, if the herniated nucleus pulposus is located on the lateral side of the spinal nerve root, the lumbar spine bends to the healthy side. (2) Restriction of lumbar activities Most patients have varying degrees of restriction of lumbar activities, which is especially obvious in the acute stage, with the most obvious restriction in forward flexion, because forward flexion can further promote the nucleus pulposus to be displaced backward and increase the pull on the compressed nerve roots. (3) Pressure pain, percussion pain and spasm of sacrospinous muscle The site of pressure pain and percussion pain basically corresponds to the vertebral space of the lesion, and is positive in 80% to 90% of cases. The percussion pain was obvious at the spinous process, which was caused by percussion vibration of the lesion. The pressure point is mainly located at 1 cm of the paravertebral area, and radiating pain along the sciatic nerve may occur. About 1/3 of patients have lumbar sacral spasm. 2. Special signs (1) Straight leg raise test and strengthening test The patient lies supine, extends the knee and passively raises the affected limb. In normal people, the nerve root has 4mm sliding degree, and the lower limb is raised to 60°~70° before feeling discomfort in the N fossa. In patients with lumbar disc herniation, the nerve root compression or adhesion reduces or disappears the sliding degree, and sciatica can occur within 60° of elevation, which is called a positive straight leg elevation test. In positive patients, slowly lowering the height of the affected limb and waiting for the radiating pain to disappear, then passively flexing the affected ankle joint to induce radiating pain again is called a positive strengthening test. Sometimes, because of the large nucleus pulposus, elevating the lower limb on the healthy side can also pull the dura to induce radiating pain on the affected sciatic nerve. (2) Femoral nerve pull test The patient is placed in a prone position with the knee joint of the affected limb fully extended. The examiner elevates the straightened lower limb so that the hip joint is in hyperextension, and the test is positive when there is pain in the femoral nerve distribution area in front of the thigh when the hyperextension reaches a certain level. This test is mainly used to examine patients with lumbar 2 to 3 and lumbar 3 to 4 disc herniation. 3, neurological manifestations (1) sensory disorders Depending on the location of the involved spinal nerve roots, abnormal sensation in the innervated area of the nerve may occur. The positivity rate is more than 80%. In the early stage, the symptoms are mostly skin sensation, and gradually numbness, tingling and hyperalgesia appear. Because the affected nerve roots are mostly single-joint and unilateral, the scope of sensory impairment is small; however, if the cauda equina nerve is involved (central type and paracentral type), the scope of sensory impairment is more extensive. (2) Decreased muscle strength 70% to 75% of patients have decreased muscle strength. In case of lumbar 5 nerve root involvement, ankle and toe dorsiflexion is decreased, and in case of sacral 1 nerve root involvement, toe and foot plantarflexion is decreased. (3) Reflex changes are also one of the typical signs that are prone to occur in this disease. When the lumbar 4 nerve root is involved, the knee reflex may be impaired, which is active in the early stage and then rapidly becomes hyporeflexic. In sacral 1 nerve root involvement, the Achilles tendon reflex is impaired. Reflex changes are more significant for the localization of the involved nerve.