From the Guidelines
Sciatica pain is primarily caused by irritation or compression of the sciatic nerve, often due to a herniated disc, spinal stenosis, or other mechanical issues. The sciatic nerve runs from the lower back through the hips and buttocks and down each leg, and its compression can lead to pain radiating down the leg, numbness, tingling, or muscle weakness in the affected leg. According to 1, sciatica is the most common symptom of lumbar radiculopathy, which involves dysfunction of a nerve root associated with pain, sensory impairment, weakness, or diminished deep tendon reflexes in a nerve root distribution.
Common Causes of Sciatica
- Herniated or slipped disc in the spine pressing on the nerve root
- Spinal stenosis (narrowing of the spinal canal)
- Piriformis syndrome (when the piriformis muscle in the buttock irritates the nerve)
- Spondylolisthesis (when one vertebra slips over another)
- Injury from trauma
- Bone spurs, tumors, or infections compressing the nerve
- Pregnancy causing temporary sciatica due to pressure on the nerve from the developing fetus
Diagnosis and Treatment
Diagnosis often involves a focused examination including straight-leg-raise testing and a neurologic examination to assess the presence and severity of nerve root dysfunction, as noted in 1. Treatment typically involves pain management with medications like NSAIDs, muscle relaxants, or prescription pain relievers, along with physical therapy to strengthen supporting muscles and improve flexibility, as suggested in 1.
Key Considerations
- A positive result on the straight-leg-raise test has a relatively high sensitivity but modest specificity for diagnosing herniated disc.
- The crossed straight-leg-raise test is more specific but less sensitive.
- Psychosocial factors and emotional distress should be assessed as they are strong predictors of low back pain outcomes.
- Age older than 65 years and certain symptoms like pseudoclaudication and radiating leg pain can be associated with lumbar spinal stenosis, although evidence is sparse and of variable quality, as discussed in 1 and 1.
From the Research
Causes of Sciatica Pain
The causes of sciatica pain can be diverse and complex. According to 2, pain along the sciatic nerve can be due to many causes, including:
- Radicular sciatica caused by compression of L5 or S1 root
- Truncular or peripheral sciatica
- Mechanical sciatica due to discal herniation in L4-L5 or L5-S1
- Inflammatory sciatica due to inflammatory processes around the disc and the nerve root
Radicular Sciatica
Radicular sciatica is divided into mechanical sciatica and inflammatory sciatica. As stated in 2, in the majority of cases, radicular pain is of mechanical origin and due to discal herniation. Additionally, 3 notes that radicular pain can be caused by herniation of the nucleus pulposus, spinal stenosis, or degenerative changes to the vertebrae.
Other Causes of Sciatica Pain
Other causes of sciatica pain include:
- Posterior intervertebral osteoarthritis and lumbar canal stenosis, as mentioned in 2
- Degenerative disc disease, which can lead to disc bulging and loss of nucleus pulposus and water content, resulting in chronic low back pain, as discussed in 4
- Truncular sciatica, which is much less frequent and should incite clinicians to investigate for pelvic tumoral infiltration, as noted in 2
- Peripheral sciatica, which is usually caused by suffering of the external popliteal nerve around the neck of the fibula, but may also be caused by compression of a ramus from the internal popliteal nerve, resulting in tarsal tunnel syndrome or Morton's syndrome, as stated in 2