If you suddenly start feeling pain in your lower back or hip that radiates to the back of your thigh and into your leg, you may have a protruding (herniated) disk in your spinal column that is pressing on the roots of the sciatic nerve. This condition is known as sciatica.

Sciatica may feel like a bad leg cramp that lasts for weeks before it goes away. You may have pain, especially when you sit, sneeze, or cough. You may also have weakness, "pins and needles" numbness, or a burning or tingling sensation down your leg.

You are most likely to get sciatica between the ages of 30 and 50 years. It may happen as a result of the general wear and tear of aging, plus any sudden pressure on the disks that cushion the bones (vertebrae) of your lower spine.

Normal lumbar anatomy/cross-section

Herniated disk (side view and cross-section)

The gel-like center (nucleus) of a disk may protrude into or through the disk's outer lining. This herniated disk may press directly on the nerve roots that become the sciatic nerve. Nerve roots may also get inflamed and irritated by chemicals from the disk's nucleus.

Approximately 1 in every 50 people will experience a herniated disk at some point in their life. Of these, 10% to 25% have symptoms that last more than 6 weeks.

In rare cases, a herniated disk may press on nerves that cause you to lose control of your bladder or bowel. If this happens, you may also have numbness or tingling in your groin or genital area. This is an emergency situation that requires surgery. Phone your doctor immediately.

Diagnosis begins with a complete patient history. Your doctor will ask you to explain how your pain started, where it travels, and exactly what it feels like.

A physical examination may help pinpoint the irritated nerve root. Your doctor may ask you to squat and rise, walk on your heels and toes, or perform a straight-leg raising test or other tests.

Most patients with sciatica have compression of the L5 or S1 nerve roots. X-rays and other specialized imaging tools such as magnetic resonance imaging (MRI) may confirm your doctor's diagnosis of which nerve roots are affected.