In the past five years since the opening of the pain clinic, we have encountered a large number of patients with lumbar disc herniation in the clinic, whose symptoms are different. What are the reasons for the symptoms? The causes of the symptoms of lumbar disc herniation are mainly due to several reasons: first, the stimulation of the nerve roots by the chemical products released from the rupture of the fibrous ring; second, the physical compression of the spinal nerve roots and the dural sac by the nucleus pulposus or the fibrous ring; third, the stimulation of the spinal cord by the narrowing of the spinal canal for various reasons; fourth, the stimulation of the nerve roots by the narrowing of the lateral saphenous fossa or intervertebral foramen for various reasons; and fifth, the stimulation of the nerve roots by the narrowing of the spinal canal for various reasons. The fifth is the irritation of nerve roots from various causes, resulting in pain, numbness, soreness and discomfort along the sciatic nerve; the sixth is the symptoms of various complications, such as pear-shaped muscle syndrome and damage to the superior gluteal nerve. Of these several causes, if a certain cause occupies a dominant role, the corresponding symptoms are manifested. Why some patients with lumbar disc herniation can only feel low back pain Patients who only have low back pain without lower limb radiating pain often have a small herniation that swells the fibrous ring, and there are rich nerve endings in the fibrous ring, which is the terminal branch of the posterior branch of the spinal nerve. The spinal nerve is mainly distributed in the low back, and after stimulation, it can be transmitted to the spinal cord along the posterior branch of the spinal nerve, and the human body feels it as low back pain. The common clinical low back pain can be divided into two types: one is the widespread dull pain of low back pain, which is slow in onset, aggravated by activity or long-term work in one posture, and reduced after rest or bed rest. The other type is low back pain with rapid onset, severe low back pain and muscle spasm in the low back, which restricts various activities due to low back pain and seriously affects life and work. This kind of low back pain is the heaviest in the first few days of onset, and then it gradually decreases, and with proper treatment, it can be relieved in a week or so. In these two kinds of back pain, the former mostly belongs to the intervertebral disc fibrous ring is still intact, while the latter mostly is a sudden rupture of all or most of the fibrous ring, making the nucleus pulposus protrude. Why do some patients with lumbar disc herniation only have leg pain but not lumbar pain? According to the statistics of Professor Hu Yougu of the Qing Medical College, the symptoms of sciatica in most patients occur after low back pain, and there is both low back pain and sciatica. A small number of patients usually have a history of chronic low back pain, but after the onset of sciatica, the low back pain is reduced or disappears. In these patients, the nucleus pulposus of the intervertebral disc mostly protrudes to one side, compressing and stimulating the unilateral nerve roots, and the compression of the dural sac is not obvious. After the nerve roots are compressed, ischemic edema occurs, followed by aseptic inflammatory infiltration. Therefore, sciatica mostly occurs gradually, starting with dull pain and gradually increasing, and the pain is mostly radiating, from the buttock, lateral thigh, lateral calf to the heel or dorsum of the foot, or in a few cases, from the foot, lateral calf, posterior lateral thigh to the buttock first. The pain worsens during coughing, sneezing, and defecation. Some patients adopt a lumbar forward flexion and hip flexion position in order to relieve the pain, so as to achieve the purpose of relaxing the tension of the sciatic nerve. When walking, they would like to take the forward position, and when resting in bed, they would like to take the bent-over side-lying flexed hip and flexed knee position, and in severe cases, they almost sleep by lying on their sides and holding their knees. The pain of such patients is reduced when riding a bicycle than when walking, also because the bicycle position is exactly the flexed hip and flexed knee position, and the nerve roots are relaxed. The nerve root pain is mainly caused by the stimulation of chemicals released by the rupture of the fibrous ring, while the numbness is caused by the physical compression of the nerve root. The sensation of a cold limb is due to a herniated disc that stimulates the sympathetic nerve fibers next to the vertebrae. Professor Ni Jiachao of the Pain Treatment Center of Beijing Xuanwu Hospital found that the skin temperature of the lower limbs increased to varying degrees by reversible blockade of the lumbar sympathetic nerve, proving that the sympathetic nerve has a regulatory role in the temperature of the lower limbs. The longitudinal distribution of sympathetic nerve chain next to the fibrous ring on both sides of the vertebral body, the expansion of the fibrous ring of the intervertebral disc to the periphery will stimulate the sympathetic nerve chain, which will reflexively cause the constriction of the blood vessels in the lower extremities and reduce the blood flow in the lower extremities. Numbness and cold sensations occur in young and middle-aged patients in the later stages of lumbar disc herniation or after a period of treatment, while in older patients numbness and coldness predominate at the beginning of the disease and pain is not obvious, which is related to the vasodilatory function in people of different age levels.