A lumbar disc herniation caused by trauma or degeneration and other causes and producing symptoms and signs consistent with the herniation is called lumbar disc herniation. Lumbar disc herniation is one of the common diseases causing lumbar pain, accounting for about 20% of lumbar pain; among them, L4/5 disc herniation is the most common, followed by L5S1 and L3/4 discs. Although lumbar disc herniation is common, its correct diagnosis is not easy and often leads to misdiagnosis and mistreatment, therefore, it is necessary to discuss the diagnosis of lumbar disc herniation from the following aspects. Symptoms 1. low back pain (lumbago): Because the herniated disc can stimulate the outer fibrous ring and the sinus nerve fibers of the posterior longitudinal ligament, patients with lumbar disc herniation often have low back pain. Low back pain can occur before, during, or after leg pain. Low back pain is widespread, mainly in the lower back or lumbosacral region, and the nature of the pain is mostly chronic and dull, but can also be acute and severe. Its incidence accounts for 96.5% in patients with lumbar disc herniation. 2. Sciatica: The incidence accounts for 82.6% of patients with lumbar disc herniation. Sciatica is common because lumbar disc herniation occurs mostly in the L4/5 or/and L5S1 spaces. The pain is mostly radiating from the buttocks, postero-lateral thigh, and postero-lateral calf to the outer ankle, dorsum of the foot, toes, heel, or sole of the foot. Very few patients may have pain radiating from the bottom to the top. Sciatica is usually unilateral, except for central herniation, which may cause bilateral sciatica or bilateral alternating sciatica. Sciatica is influenced by abdominal pressure and changes in position. The pain increases when coughing, sneezing, or straining to defecate; flexing the waist, hip, and knee increases the volume of the spinal canal and relaxes the sciatic nerve, thus reducing the pain. “Walking less than a few dozen meters, cycling dozens of miles” is a specific description of the characteristics of sciatica in patients with lumbar intervertebral disc herniation. First lumbar pain and then leg pain, and finally leg pain more than lumbar pain are the main symptom characteristics of patients with lumbar disc herniation. 3. lower abdomen or anterior medial thigh pain: high lumbar disc herniation causing L1, L2, L3 nerve root involvement may cause groin or anterior medial thigh pain in the corresponding nerve distribution area. l4/5 or L5S1 disc herniation may also cause entrapment pain in the groin area and perineum. Since 2/3 of the sinus nerve is composed of sympathetic nerves and 1/3 of the somatic nerves, the herniated L4/5 and L5S1 discs stimulate the sympathetic nerve fibers also causing pain in the lower abdomen, anterior medial thigh, and perineum as an explanation. 4, intermittent claudication (intermitent creep): patients walking a certain distance after feeling pain and numbness in the lumbar and leg aggravated, take a squatting or sitting position, the symptoms ease or disappear, this performance is called intermittent claudication. The explanation is: when walking, the venous plexus obstructed in the spinal canal gradually filled with blood, increasing the degree of congestion and pressure on the nerve root, so the symptoms increased; when taking a squatting or sitting position, the volume of the spinal canal expands, the venous return flow is smooth, and the symptoms are reduced. 5, numbness or coldness of the affected limb: the protruding disc tissue compresses or stimulates the proprioceptive and tactile fibers, causing numbness in the area of the affected nerve root distribution. The herniated disc tissue stimulates the sympathetic nerve fibers of the paravertebral nerve or the sympathetic nerve fibers of the sinus vertebral nerve, which reflexively causes vasoconstriction of the lower extremity, and the patient feels coldness in the affected extremity, a phenomenon also called cold sciatica. 6, neurological impairment: lower limb weakness or paralysis: protruding disc compression of nerve roots is severe and prolonged, which can cause weakness of the affected innervated muscles, or even paralysis. Sphincter and sexual dysfunction: central, giant or free type herniated discs, which compress the cauda equina nerve, can cause cauda equina syndrome, manifesting as anal and urethral sphincter and sexual dysfunction, such as constipation, urinary difficulty or incontinence, impotence, etc. Signs 1, forced position and abnormal gait: severe symptoms can be manifested as forced bending over the hip position and restrained or limping gait. 2. Lumbar spine morphology and mobility: Patients with severe symptoms of lumbar disc herniation often show changes in lumbar spine morphology and reduced mobility. For example, the physiological anterior convexity of the lumbar spine becomes shallow, disappears or becomes posteriorly convex, convex to the healthy side (the herniated disc is in the axillary part of the nerve root) or to the affected side (the herniated disc is in the shoulder part of the nerve root); the lumbar forward flexion, posterior extension, lateral flexion and rotation range is limited. Flexion to the affected side and simultaneous limitation of posterior extension are typical signs of lumbar disc herniation. 3.Pressure pain and radiating pain: When lumbar disc herniation is accompanied by radiculitis, there may be obvious pressure pain on the affected side of the spinal space of the lesion and radiation to the distribution area of the nerve. 4. Muscle atrophy and muscle weakness: muscle atrophy and muscle weakness can be caused by the herniated disc compressing the nerve root and the painful affected limb not daring to exert. For example, the involvement of L5 spinal nerve may cause weakness of thumb dorsiflexion, toe dorsiflexion and ankle dorsiflexion, while the involvement of S1 spinal nerve may cause weakness of mother flexor and ankle flexor. 5. Changes in skin sensation and tendon reflexes: Patients with lumbar disc herniation may have decreased superficial skin sensation and weakened or absent tendon reflexes in the nerve distribution area, such as weakened knee reflexes when the L4 nerve is involved, and weakened or absent Achilles tendon reflexes when the S1 nerve is involved. 6. Straight leg elevation test (Lasegue sign) and strengthening test (Bragard sign): When lumbar disc herniation involves nerve roots and causes radiculitis, it may show positive straight leg elevation test and strengthening test, or even positive healthy leg elevation (Fajersztajn sign, also known as cross test) and strengthening test. 7.Supine jacking test: The patient lies on his back with the occipital and heel support to lift the buttocks and back, and if there is radiating pain in the affected limb, it is positive. If there is no radiating pain, it is also positive if the patient maintains a coughing motion or holds his breath until his face turns red. Imaging A typical lumbar disc herniation may have imaging changes. 1. X-ray plain film: It shows indirect signs of lumbar disc herniation, such as shallowing, disappearance or retroflexion of the physiological anterior lumbar convexity, lumbar lateral convexity, narrowing of the lumbar intervertebral space with disc herniation, unequal width from left to right, equal width from front to back or even narrowing from front to back, sclerosis and lip-like hyperplasia of the relative margins, small intervertebral foramen and Schmorl’s node. The oblique film has no specific value, but can exclude lesions of the vertebral arch. 2.CT: It shows the direct signs of lumbar disc herniation, such as the location, size and nature of the disc herniation (with or without calcification), fullness of the lateral saphenous fossa, and thickening or submergence of the nerve roots. The accuracy of the diagnosis of lumbar disc herniation is 70%, and the main signs are: (1) posterior and/or lateral protrusion of the disc, with individual protrusion into the intervertebral foramen or outside the foramen. (2) Fullness of the lateral saphenous fossa, flooding of the nerve roots, or edema and thickening of the nerve roots stimulated by the compression of the herniated disc. (3) Loss of the anterior dural space and deformation of the dural sac by compression (Figure 7). (4) Dotted or/and mass-like high-density shadow may appear in the herniated disc, which is a manifestation of disc calcification. To accurately describe the size and location of the herniated disc, a three-dimensional, two-section, three-directional view can be used. Sagittal plane, showing the thickness of the herniated disc. There are three levels: Ⅰ, Ⅱ and Ⅲ: the Ⅰ level shows the disc level; the Ⅱ level shows the upper disc level, i.e., from the level of the inferior arch notch of the previous vertebral body to the level of the upper disc boundary; and the Ⅲ level shows the lower disc level, from the lower disc boundary to the level of the superior arch notch of the next vertebral body. The cross-section is oriented left and right, showing the extent (width) of the disc protrusion to the left and right. There are four zones: zone 1 is in the middle 1/3 of the spinal canal, zone 2 is in the left or right 1/3 of the spinal canal, zone 3 is in the intervertebral canal, and zone 4 is outside the external opening of the intervertebral canal. Anterior-posterior orientation, showing the degree of posterior protrusion of the disc (length). There are four domains: a, b, c, and d. The disc in domain a protrudes backward by 1/4 of the sagittal diameter of the spinal canal, in domain b by 1/2, in domain c by 3/4, and in domain d by 4/4. 3. MRI: MRI is feasible when there is a contradiction between clinical manifestations and CT signs. MRI can reflect the imaging characteristics of multiple lumbar vertebrae and discs in sagittal or coronal position, which is valuable for confirming the diagnosis of disc protrusion or excluding other pathologies such as tumor and tuberculosis. It is valuable to confirm the diagnosis of disc herniation or exclude other pathologies such as tumor and tuberculosis, with an accuracy of 90%. Diagnosis 1. Diagnostic basis of lumbar disc herniation Diagnosis of lumbar disc herniation must combine symptoms, signs and imaging data in a comprehensive consideration and analysis to ensure the consistency of the three, and the consistency is expressed in the following three aspects. (1) Lateral consistency: In most cases, the side of the lumbar disc protrusion on the image is consistent with the side of the symptoms and signs. For example, if CT shows that the disc protrudes to the left side, the patient should feel pain in the left leg, and physical examination reveals positive straight leg raising test and strengthening test on the left side, etc. (2) Consistent level: CT shows that the level (gap) of the herniated disc, the involved nerve and the lesioned nerve reflected by the chief complaint area and physical signs are consistent. (3) Degree consistency: generally the larger the imaging shows the herniation, the heavier the clinical performance symptoms and signs, but this is not absolute and is also influenced by the relationship between the location of the herniated disc and the affected nerve root. 2, the localization of lumbar disc herniation diagnosis (1) lumbar 1 to 3 disc herniation: the disc herniation between the thoracic 12 and lumbar 3 vertebrae is called high lumbar disc herniation, less common, compression of the lumbar 1 to 3 nerves consisting of the closed foraminal nerve and femoral nerve, because the lumbar 1 to 3 spinal nerves mostly do not have their own special signs, often jointly innervate the iliopsoas muscle or with the lumbar 4 nerve innervate the internal femoral retractor group and quadriceps muscle. Sensory disturbances in compression In compression of the lumbar 1 nerve, there is pain and numbness in the upper 1/3 of the oblique band from the groin to the knee. In compression of the lumbar 2 nerve, pain and numbness in the anterior 1/3 oblique band of the mid-thigh. Pain and numbness in the lower anterior 1/3 oblique band of the thigh with compression of the lumbar 3 nerve. Manifestations of dyskinesia when compression occurs Weakness of hip forward flexion caused by iliopsoas muscle involvement. When the internal femoral retractor muscle group innervated by the lumbar 2 to 4 spinal nerves is involved, the hip joint is weak in motion when it is internally retracted from the external booth. When the femoral nerve, which is composed of three spinal nerve fibers from lumbar 2 to 4 and innervates the quadriceps muscle, is involved, it shows atrophy of the quadriceps muscle, weakness of knee extension, and weakening or disappearance of knee reflex and testicular reflex. (2) Lumbar 3 to 4 disc herniation: compression of the lumbar 4 nerve root, the patient has pain and numbness in the back, lumbosacral region and lateral thigh, calf and medial foot. Weakness of dorsal extension and inversion movements of the foot. Because the lumbar 4 nerve is involved in the innervation of the quadriceps muscle, symptoms and signs such as weakness of quadriceps movement, weakness of knee extension, and weakened or absent knee reflex may also occur. (3) Lumbar 4-5 disc herniation: compression of the lumbar 5 nerve root. It mainly involves the tibialis anterior and extensor muscles, often with pain in the low back and lumbosacral region, and radiating pain and numbness to the back of the thigh and calf to the dorsum of the foot and toes, as well as weakness of the dorsal extension of the parent toe, and in severe cases, foot drop. (4) Lumbar 5 to sacral 1 disc herniation: compression of sacral 1 nerve roots, sensory disorders manifested as pain in the low back, sacrococcygeal region, buttocks, and radiating pain and numbness to the posterior side of the thigh and calf to the bottom of the foot, motor disorders mainly caused by the involvement of peroneus longus and shortus muscles at the same time, weakening or loss of foot external rotation muscle strength, and the involvement of the calf triceps muscle caused by the ankle joint, foot and mother toe flexion weakness, Achilles tendon Signs and symptoms such as reduced or absent reflexes. The above are the common symptoms and signs caused by the compression of nerve roots by the lateral herniation. The central herniation may compress the nerve roots one to two positions below the herniated space or even the entire cauda equina, causing pain and numbness in the lumbar region and/or both lower extremities, and in severe cases, it may lead to weakness or paralysis of the bladder and rectal sphincter, resulting in symptoms of cauda equina syndrome such as weakness or incontinence of defecation and signs such as weakening or disappearance of Achilles tendon reflex and testicular reflex. In contrast, foraminal and extreme lateral herniations can compress the nerve roots emanating from the same or even the previous interspace, causing the corresponding symptoms and signs. If there is only a herniated disc on the image without symptoms and signs consistent with the herniation, the diagnosis of lumbar disc herniation can only be made on the image, but not clinically. Differential diagnosis 1. Lumbar spondylolisthesis: sciatica is mostly bilateral. In the late stage, there is often numbness in the saddle area, weakness of the lower limbs and increased anterior protrusion of the lumbar spine. Lateral lumbar spine film shows lumbar spine slippage, and oblique lumbar spine film shows collapse of the vertebral arch. 2, spinal tumor: lumbar and leg pain is persistent, especially at night, and may be accompanied by symptoms and signs of the primary tumor. Laboratory tests mostly include increased blood sedimentation. Imaging examination shows that the vertebral body and arch root are destroyed, but the vertebral space is not narrow. 3, lumbar spine tuberculosis: lumbar pain is persistent. X-ray examination shows narrowing of the joint space and destruction of the vertebral body. There is occasionally a cold thick swelling shadow next to the lumbar spine. It is not difficult to differentiate according to symptoms and signs. The symptoms of lumbar spinal stenosis are often the main signs and symptoms of the disease. If necessary, myelography or CT examination should be performed to confirm the diagnosis. 5, lumbar myofascial pain syndrome: it is an extra-vertebral canal lesion with limited pressure points in the lumbar region, and the test that makes the volume of the spinal canal smaller (lumbar posterior extension test) is negative.