Sciatica: Definition, Causes, and the Best Treatment

Sciatica is one of the most common causes of pain that travels from the lower back into the leg. Rather than being a diagnosis itself, sciatica is a symptom that occurs when the sciatic nerve becomes irritated, inflamed, or compressed. People with sciatica often experience pain that begins in the lower back or buttock and radiates down the back or side of the thigh, sometimes extending into the calf, ankle, or foot.

The sciatic nerve is the largest and longest nerve in the human body, extending from the lower spine through the buttocks and down each leg. Because it supplies sensation and muscle function to much of the lower extremity, irritation of this nerve can cause more than pain. Many people also experience numbness, tingling, muscle weakness, or difficulty walking, standing, or sitting comfortably for extended periods.

Sciatica is most commonly caused by conditions affecting the lumbar spine, including herniated discs, bulging discs, lumbar spinal stenosis, degenerative disc disease, osteoarthritis, and piriformis syndrome. Less commonly, muscle spasms, spondylolisthesis, or other conditions affecting the lower back or pelvis may also contribute to sciatic nerve irritation. Because several disorders can produce nearly identical symptoms, identifying the underlying cause is the most important step in choosing the most effective treatment.

Most cases of sciatica improve with conservative care, especially when treatment begins early. However, severe or progressive symptoms, particularly significant leg weakness or loss of bowel or bladder control, require immediate medical evaluation because they may indicate a medical emergency.