Your sciatic nerve begins at your spinal cord, runs through your hips and buttocks, and then branches down each leg.
The sciatic nerve is your body’s longest nerve and one of the most important ones. It has a direct effect on your ability to control and feel your legs. When this nerve is irritated, you’ll experience sciatica.
Sciatica is a sensation that can manifest itself as a moderate to severe pain in your back, buttocks, and legs. You may also feel weakness or numbness in these areas.
Sciatica is a symptom caused by an underlying injury to your sciatic nerve or an area that affects the nerve, such as your vertebrae, which are the bones in your neck and back.
As many as 40 percent of people will get it at some point during their lives. It becomes more frequent as you age.

Sciatica is a very distinct type of symptom. If you’re experiencing pain that flows from your lower back through your buttock area and into your lower limbs, it’s typically sciatica.
Sciatica is the result of damage or injury to your sciatic nerve, so other symptoms of nerve damage are usually present with the pain. Other symptoms may include the following:
  • You may have pain that gets worse with movement.
  • You may have numbness or weakness in your legs or feet, which is usually felt along your sciatic nerve pathway. In severe cases, you may experience a loss of feeling or movement.
  • You may feel the sensation of pins and needles, which involves a painful tingling in your toes or feet.
  • You may experience incontinence, which is the inability to control your bladder or bowels. This is a rare symptom of cauda equina syndrome (CES), which is described below, and it calls for immediate emergency attention.

Sciatica can be caused by several conditions that involve your spine and can affect the nerves running along your back. It can also be caused by an injury, for example from falling, or spinal or sciatic nerve tumors.
Common conditions that can cause sciatica are described below.

Herniated disks

Your vertebrae, or spinal bones, are separated by pieces of cartilage. Cartilage is filled with a thick, clear material to ensure flexibility and cushioning while you move around. Herniated disks occur when the first layer of the cartilage rips.
The substance inside can compress your sciatic nerve, resulting in lower limb pain and numbness. It’s estimated that 1 to 5 percentTrusted Source of all people will have back pain caused by a slipped disk at some point in their lives.

Spinal stenosis

Spinal stenosis is also called lumbar spinal stenosis. It’s characterized by the abnormal narrowing of your lower spinal canal. This narrowing puts pressure on your spinal cord and your sciatic nerve roots.

Spondylolisthesis

Spondylolisthesis is one of the associated conditions of degenerative disk disorder. When one spinal bone, or vertebra, extends forward over another, the extended spinal bone can pinch nerves that make up your sciatic nerve.

Piriformis syndrome

Piriformis syndrome is a rare neuromuscular disorder in which your piriformis muscle involuntarily contracts or tightens, causing sciatica. Your piriformis muscle is the muscle that connects the lower portion of your spine to your thighbones.
When it tightens, it can put pressure on your sciatic nerve, leading to sciatica. Piriformis syndrome can worsen if you sit for long periods, fall, or experience a car crash.


Certain behaviors or factors can raise your risk of developing sciatica. The most common factors for developing sciatica include the following:
  • As your body ages, it becomes more likely that parts will wear out or break down.
  • Certain careers place a lot of strain on your back, especially those that involve lifting heavy objects, sitting for extended periods, or twisting movements.
  • Having diabetes can increase your risk of nerve damage.
  • Smoking can cause the outer layer of your spinal disks to break down.

Diagnosing sciatica

Sciatica is a symptom that varies from one person to another and depends on the condition that’s causing it. To diagnose sciatica, your doctor will first want to get your full medical history.
This includes whether you have had any recent injuries, where you feel the pain, and how the pain feels. They’ll want to know what makes it better, what makes it worse, and how and when it started.
The next step is a physical exam that’ll include testing your muscle strength and reflexes. Your doctor might also ask you to do some stretching and moving exercises to determine which activities cause more pain.
The next round of diagnosis is for people who have dealt with sciatica for longer than a month or have a major illness, such as cancer.
Nerve tests will allow your doctor to examine how nerve impulses are being conducted by your sciatic nerve and learn if there are any abnormalities. These tests may help locate the area involved and the degree to which the impulse is being slowed.
Imaging tests will allow your doctor to get a look at your spine, which will help them determine the cause of your sciatica.
The most common imaging tests used to diagnose sciatica and find its cause are spinal X-rays, MRIs, and CT scans. Normal X-rays will not be able to provide a view of sciatic nerve damage.
An MRI uses magnets and radio waves to create detailed images of your back. A CT scan uses radiation to create detailed images of your body.
Your doctor may order a CT myelogram. For this test, they’ll inject a special dye into your spine to help produce clearer pictures of your spinal cord and nerves.