What You Need to Know About Sciatica

The term sciatica describes the symptoms of leg pain—and possibly tingling, numbness, or weakness—that originate in the lower back and travel through the buttock and down the large sciatic nerve in the back of each leg.

Sciatica (pronounced sigh-at-eh-kah) is not a medical diagnosis in and of itself—it is a symptom of an underlying medical condition. Common lower back problems that can cause sciatica symptoms include a lumbar herniated disc, degenerative disc disease, spondylolisthesis, or spinal stenosis.

Sciatica Nerve Pain

Sciatica is often characterized by one or more of the following symptoms:

• Constant pain in only one side of the buttock or leg (rarely in both legs)
• Pain that is worse when sitting
• Leg pain that is often described as burning, tingling, or searing (versus a dull ache)
• Weakness, numbness, or difficulty moving the leg, foot, and/or toes
• A sharp pain that may make it difficult to stand up or walk
• Pain that radiates down the leg and possibly into the foot and toes (it rarely occurs only in the foot)

Sciatic pain can vary from infrequent and irritating to constant and incapacitating. Symptoms are usually based on the location of the pinched nerve.

While symptoms can be painful and potentially debilitating, it is rare that permanent sciatic nerve damage (tissue damage) will result, and spinal cord involvement is possible but rare.

See Sciatica Symptoms

The Sciatic Nerve and Sciatica

The sciatic nerve is the largest single nerve in the body and is made up of individual nerve roots that start by branching out from the spine in the lower back and then combine to form the “sciatic nerve.” Sciatica symptoms occur when the large sciatic nerve is irritated or compressed at or near its point of origin.

See Lumbar Spine Anatomy and Pain

• The sciatic nerve starts in the lower back, typically at lumbar segment 3 (L3).
• At each level of the lower spine a nerve root exits from the inside of the spinal canal, and each of these respective nerve roots then come together to form the large sciatic nerve.
• The sciatic nerve runs from the lower back, through the buttock, and down the back of each leg.
• Portions of the sciatic nerve then branch out in each leg to innervate certain parts of the leg—the thigh, calf, foot, and toes.

The specific sciatica symptoms—the leg pain, numbness, tingling, weakness, and possibly symptoms that radiate into the foot—largely depend on where the nerve is pinched. For example, a lumbar segment 5 (L5) nerve impingement can cause weakness in extension of the big toe and potentially in the ankle.

Watch Sciatic Nerve Anatomy Video

The Course of Sciatica Pain

Sciatica rarely occurs before age 20, and becomes more commonplace in middle age. It is most likely to develop around age 40 or 50.

Perhaps because the term sciatica is often used loosely to describe leg pain, estimates of its prevalence vary widely. Some researchers have estimated it will affect up to 43% of the population at some point.^{1, 2}

Often, a particular event or injury does not cause sciatica—rather it tends to develop over time.

The vast majority of people who experience sciatica get better within a few weeks or months and find pain relief with nonsurgical sciatica treatment.¹ For others, however, the leg pain from a pinched nerve can be severe and debilitating.

See Myths About Sciatica Treatment Options

Seeing a doctor for sciatica pain is advised, both for learning how to reduce the pain and to check for the possibility of a serious medical issue.

When Sciatica Is Serious

Certain sciatica symptoms, while rare, require immediate medical, and possibly surgical, intervention. These include, but are not limited to, progressive neurological symptoms (e.g. leg weakness) and/or bowel or bladder dysfunction (cauda equina syndrome). Infection or spinal tumors can also cause sciatica.

See When Back Pain May Be a Medical Emergency

Because sciatica is caused by an underlying medical condition, treatment is focused on addressing the cause of symptoms rather than just the symptoms. Treatment is usually self-care and/or nonsurgical, but for severe or intractable pain and dysfunction it may be advisable to consider surgery.

When discussing sciatica, it is important to understand the underlying medical cause, as effective treatment will focus on addressing the pain’s root cause as well as alleviating acute symptoms.

6 Most Common Causes of Sciatica

The following six lower back problems are the most common causes of sciatica:

• • Lumbar herniated disc
    A herniated disc occurs when the soft inner material of the disc leaks out, or herniates, through the fibrous outer core and irritates or pinches the contiguous nerve root.

Other terms used to refer to a herniated disc are slipped disc, ruptured disc, bulging disc, protruding disc, or a pinched nerve. Sciatica is the most common symptom of a lumbar herniated disc.

• • Degenerative disc disease
    While some level of disc degeneration is a natural process that occurs with aging, for some people one or more degenerated discs in the lower back can also irritate a nerve root and cause sciatica.

Degenerative disc disease is diagnosed when a weakened disc results in excessive micro-motion at that spinal level, and inflammatory proteins from inside the disc become exposed and irritate the nerve root(s) in the area.

Read more: Lumbar Degenerative Disc Disease (DDD)

Bone spurs, which may develop with spinal degeneration, also may press against a nerve, resulting in sciatica.

Read more: Bone Spurs (Osteophytes) and Back Pain

• • Isthmic spondylolisthesis
    This condition occurs when a small stress fracture allows one vertebral body to slip forward on another; for example, if the L5 vertebra slips forward over the S1 vertebra.

See All about L5-S1 (Lumbosacral Joint)

With a combination of disc space collapse, the fracture, and the vertebral body slipping forward, the nerve can get pinched and cause sciatica.

Read more: Isthmic Spondylolisthesis

• • Lumbar spinal stenosis
    This condition commonly causes sciatica due to a narrowing of the spinal canal. Lumbar spinal stenosis is related to natural aging in the spine and is relatively common in adults older than age 60.

The condition typically results from a combination of one or more of the following: enlarged facet joints, overgrowth of soft tissue, and a bulging disc placing pressure on the nerve roots, causing sciatica pain.

Lumbar spinal stenosis commonly occurs along with spinal arthritis, and arthritis can also cause or contribute to sciatica symptoms.

Read more: Lumbar Spinal Stenosis: A Definitive Guide

• • Piriformis syndrome
    The sciatic nerve can get irritated as it runs under the piriformis muscle in the buttock. If the piriformis muscle irritates or pinches a nerve root that comprises the sciatic nerve, it can cause sciatica-type pain.

This is not a true lumbar radiculopathy, which is the clinical definition of sciatica. However, because the leg pain can feel the same as sciatica or radiculopathy, it is sometimes referred to as sciatica.

Read more: What is Piriformis Syndrome?

• • Sacroiliac joint dysfunction
    Irritation of the sacroiliac joint—located at the bottom of the spine—can also irritate the L5 nerve, which lies on top of the sacroiliac joint, causing sciatica-type pain.

Again, this is not a true radiculopathy, but the leg pain can feel the same as sciatica caused by a nerve irritation.

Read more: Sacroiliac Joint Dysfunction (SI Joint Pain)

More Causes of Sciatica and Sciatica-Type Symptoms

In addition to the most common causes, a number of other conditions can cause sciatica, including:

• • Pregnancy. The changes the body goes through during pregnancy, including weight gain, a shift of one’s center of gravity, and hormonal changes, can cause sciatica during pregnancy.
  • Scar tissue. If scar tissue—also called epidural fibrosis—compresses to a lumbar nerve root, it can cause sciatica.
  • Muscle strain. In some cases, inflammation related to a lower muscle strain and/or muscle spasm can put pressure on a nerve root and cause sciatica pain.

Watch Video: What Is Your Back Muscle Spasm Telling You?

• Spinal tumor. In rare cases, a spinal tumor can impinge on a nerve root in the lower back and cause sciatica symptoms. It is possible for tumors to originate in the spine, but more commonly spinal tumors develop as cancer from a different part of the body metastasizes and spreads to the spine.
• Infection. While rare, an infection that occurs in the low back can affect the nerve root and cause sciatica.
• Fracture. If a fracture occurs in a lumbar vertebra, it is possible for symptoms to include sciatica. Most fractures occur because of a serious trauma (such as a car accident or a fall) or because the bone has become weak due to osteoporosis or another underlying condition or medication.
• Ankylosing spondylitis. This condition is characterized by chronic inflammation in and around the spine. Often symptoms first show up in the sacroiliac joints, causing sacroiliitis, and symptoms may include sciatica

• Risk Factors for Developing Sciatica

  Some research indicates that those who are overweight, obese, or who smoke are at added risk of developing sciatica and of requiring hospitalization for sciatica.^3,4 Tobacco use, or any type of nicotine intake, has been shown to contribute to disc degeneration.^5,6