This symptom may be caused by lumbar disc bulging

Lumbar disc bulging is a common lumbar spinal disease. It is usually caused by external pressure that damages the lumbar bones and ruptures the lumbar nucleus pulposus tissue, causing lumbar disc bulging. The most obvious symptoms of lumbar disc bulging are low back pain, numbness in the lower limbs, and limited movement.

Clinical manifestations

1. Symptoms

1. Low back pain

It is the first symptom that occurs in most patients, with an incidence of about 91%. Because the outer layer of the annulus fibrosus and the posterior longitudinal ligament are stimulated by the nucleus pulposus, induced pain in the lower back is produced through the vertebral nerve, sometimes accompanied by buttocks pain.

2. Radiating pain in the lower limbs

Although high-level lumbar disc herniation (L2-3, L3-4) can cause femoral neuralgia, it is rare in clinical practice, accounting for less than 5%. The vast majority of patients have herniation between L4 and 5, or L5 and S1, and present with sciatica. Typical sciatica is pain that radiates from the lower back to the buttocks, back of the thigh, outer side of the calf to the foot. The pain is aggravated by increased abdominal pressure due to sneezing and coughing. The radiating pain is mostly on one side of the limbs, and only a very small number of patients with central or paracentral nucleus pulposus herniation show symptoms in both lower limbs. There are three causes of sciatica: ① The ruptured intervertebral disc produces chemical stimulation and autoimmune reactions, causing chemical inflammation of the nerve roots; ② The protruding nucleus pulposus compresses or stretches the inflamed nerve roots, blocking their venous return, further aggravating edema and increasing sensitivity to pain; ③ The compressed nerve roots are ischemic. The above three factors are interrelated and aggravate each other.

3. Cauda equina symptoms

The nucleus pulposus protruding to the rear or the prolapsed and free intervertebral disc tissue compresses the cauda equina, which mainly manifests as difficulty in defecation and urination, and abnormal sensation in the perineum and perianal area. In severe cases, symptoms such as incontinence and incomplete paralysis of both lower limbs may occur, which are rare in clinical practice.

(II) Physical signs

1. General signs

(1) Lumbar scoliosis is a postural compensatory deformity that relieves pain. Depending on the location of the nucleus pulposus protrusion and the relationship between the nerve roots, the spine may bend toward the healthy side or the affected side. If the protrusion of the nucleus pulposus is located on the inner side of the spinal nerve root, the lumbar vertebra will bend toward the affected side because bending the spine toward the affected side can reduce the tension of the spinal nerve root. Conversely, if the protrusion is located on the outer side of the spinal nerve root, the lumbar vertebra will mostly bend toward the healthy side.

(2) Limited lumbar movement Most patients have limited lumbar movement to varying degrees, which is particularly obvious in the acute phase. Among them, the most obvious is the limitation in flexion, because the flexion position can further promote the posterior displacement of the nucleus pulposus and increase the traction on the compressed nerve roots.

(3) Tenderness, percussion pain, and sacrospinal muscle spasm The location of tenderness and percussion pain is basically consistent with the intervertebral space of the lesion, and 80% to 90% of cases are positive. The percussion pain is most obvious at the spinous process, which is caused by the vibration of the diseased area caused by percussion. The tenderness point is mainly located 1 cm beside the vertebrae, and radiating pain may occur along the sciatic nerve. About 1/3 of patients have lumbar sacrospinal muscle spasm.

2. Special signs

(1) Straight-leg raising test and strengthening test The patient lies on his back with his knee extended and the affected limb passively raised. The normal nerve root has a sliding range of 4mm, and discomfort in the popliteal fossa is felt only when the lower limb is raised to 60° to 70°. In patients with lumbar disc herniation, the nerve roots are compressed or adhered, causing the sliding degree to be reduced or eliminated. Sciatica will occur if the nerve roots are raised within 60°, which is called a positive straight leg raising test. In positive patients, the height of the affected limb is slowly lowered until the radiating pain disappears. Then the affected ankle joint is passively flexed to induce radiating pain again, which is called a positive enhancement test. Sometimes, because the nucleus pulposus is large, raising the healthy lower limb can also pull the dura mater and induce radiating pain in the sciatic nerve on the affected side.

(2) Femoral nerve traction test: The patient lies prone with the knee joint of the affected limb fully extended. The examiner raises the straightened lower limb so that the hip joint is in a hyperextended position. When hyperextension to a certain extent causes pain in the femoral nerve distribution area in the front of the thigh, it is positive. This test is mainly used to examine patients with L2-3 and L3-4 intervertebral disc herniation.

3. Neurological manifestations

(1) Sensory impairment: Depending on the location of the affected spinal nerve root, sensory abnormalities may occur in the area innervated by the nerve. The positive rate is over 80%. In the early stages, it often manifests as skin hypersensitivity, which gradually leads to numbness, tingling and decreased sensation. Because the affected nerve roots are mostly single-segment and unilateral, the range of sensory impairment is relatively small; however, if the cauda equina is affected (central and paracentral types), the range of sensory impairment is more extensive.