What Causes Sciatica and Sciatic Nerve Pain?

Sciatica and Sciatic Nerve Pain

Written by Jeremy D. Earle, JD

September 4, 2022

What is Sciatic Nerve Pain?

Are you looking for a way to get rid of your sciatica? The first step is to ascertain the underlying reason. Continue reading to discover some of the most frequent causes of sciatica—and how to treat them.

You may be shocked to find that sciatica is not a disease but rather a term used to describe symptoms associated with various lower back disorders. You may also be unconcerned, since whatever the reason, sciatica is painful.

Sciatica is the term used to describe pain when anything compresses, irritates, or inflames the sciatic nerve or nerve roots that later form the sciatic nerve. Pain along the length of your leg—you may experience it anywhere from your buttocks to your ankle.

Are you looking for a way to get rid of your sciatica? The first step is to ascertain the underlying reason. Continue reading to discover some of the most frequent causes of sciatica—and how to treat them.

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What Is the Cause of Sciatica?

“Sciatica is a sign of a more serious underlying condition,” explains Brian R. Subach, MD, a neurosurgeon at National Spine and Pain in Maryland. Numerous spinal diseases may result in sciatic nerve compression. The six most frequent are as follows:

  • Bulging or herniated disc
  • Lumbar spinal stenosis
  • Spondylolisthesis
  • Spinal cord injury caused by trauma
  • Piriformis syndrome
  • Spinal tumor

While these conditions may cause sciatica, disc herniation is far and away from the most prevalent. Indeed, according to some studies, up to 90% of sciatica cases are caused by a herniated disc in the lumbar spine.

The most common cause of sciatica is a bulging or herniated lumbar disc.

The discs in the spine provide a variety of roles, including providing flexibility to the spine, functioning as cushions for the vertebrae, and uniformly distributing the weight put on the spine between the discs. Bulging and herniation of discs are more common in the lumbar spine simply because that region of the spine bears the full weight of the upper body and any things that may need to be picked up.

Bulging and herniated discs are similar but not identical. A bulging disc is a disc condition that occurs inside the disc. The disc’s gel-like core (nucleus pulposus) stays “contained” inside the disc’s tire-like outer wall (annulus fibrosus), but the outside wall may stretch enough to push on a neighboring nerve or nerve root.

When the disc’s nucleus ruptures through the annulus fibrosus, this is referred to as a herniated disc. This condition is referred to as non-contained disc disease. Whether a disc bulges or herniates, disc material may pressure fragile nerve tissue, resulting in sciatica. Compression of the sciatic nerve may occur on just one side, resulting in symptoms on only one side of the body, or it can occur on both sides, resulting in symptoms on both sides (bilateral sciatica).

In any case, the effects of a herniated disc are far severe. Not only does a herniated disc push the nerve root directly against the bony spinal canal’s interior, but the disc material itself

contains an acidic chemical irritant (hyaluronic acid) that promotes nerve inflammation. Stated, disc herniation is a two-for-one bargain that you do not want.

Compression Direct

The traditional sciatica mechanism is direct compression. When the jelly-like nucleus of the disc bulges or bursts through the tough annulus fibrosus, that portion of the disc often pushes on a neighboring nerve root branching off the spinal cord and leaving the vertebra. Herniated discs in the lumbar and sacral regions of the spine often compress one of the nerve roots that ultimately join to form the sciatic nerve in the buttocks, resulting in sciatica.

Inflammation Due to Chemicals

Direct compression does not resolve the problem of a herniated disc. The nucleus, the disc’s delicate inner layer, is primarily water and collagen, but it releases potent chemicals as it punches through the annulus. These substances promote inflammation in the local location, aggravating any compressed nerve roots.

Disc Degeneration is a common cause of sciatica.

Although disc degeneration is technically a risk factor for herniated discs rather than a cause of sciatica, it often results in sciatica that we would foolishly disregard.

Disc degeneration, or degenerative disc disease (DDD), is a prevalent and usually unavoidable element of aging. Intervertebral discs dry up over time—years and decades—a process termed disc desiccation. The discs’ water content decreases, making them weaker, more brittle, and prone to herniation.

Although DDD is extremely common and almost unavoidable, there are some lifestyle changes you can make to reduce your risk of or slow the progression of disc degeneration, including the following:

Using proper lifting mechanics

Maintaining a healthy weight

Avoiding smoking and limiting alcohol consumption

Sitting less and moving more

The third most common cause of sciatica is lumbar spinal stenosis.

Spinal nerve roots break out from the spinal cord through bone and ligament tunnels called neural foramina. Nerve roots travel through these holes, fuse to become nerves, and then expand to the rest of your body.

When spinal stenosis occurs, these foramina constrict or get blocked, compressing the nerves. The canal’s space is often reduced as a consequence of disc herniation. However, it may also be reduced due to other factors such as:

Spinal injuries, such as vertebral fractures or dislocations caused by trauma

Bone spurs—abnormal growth of bone—or spinal cancers

Strengthening of the ligaments that connect the spine Spondylolisthesis is a common cause of sciatica.

Spondylolisthesis is a condition that most often occurs in the lumbar spine. It happens when one vertebra slides forward and collides with another. When a vertebra slides and displaces, it exerts pressure on the nerves or nerve roots underneath it. This finally produces compression, which often manifests as sciatica pain.

Developmental spondylolisthesis is either present at birth or develops throughout infancy. On the other hand, acquired spondylolisthesis may be induced by:

Degenerative changes in the spine (spinal degeneration)

Physical stress from sports such as weightlifting or gymnastics

Trauma, such as a car accident

“During the physical examination, the patient often complains of greater back discomfort while arching into extension owing to facet joint irritation. “Frequently, the diagnosis may be

established with basic plain radiographs — such as an X-ray — taken in the standing position,” Dr. Subach explains.

#5: Trauma is a frequent cause of sciatica

In certain instances, trauma may be the direct cause of sciatica. Motor vehicle accidents (MVA’s), falls, and contact sports are examples (e.g., football). The impact may cause nerve damage, or bone shards may compress the nerves.

Along with high-energy traumas such as MVAs, other types of trauma may result in sciatica. These include pelvic fractures or hip dislocations (traction-induced sciatica), which cause surrounding hamstrings to tear and irritate the sciatic nerve. Additionally, it may be caused by items infiltrating the body and severing/tearing the nerve, such as a bullet or knife.

Common Cause #6 of Sciatica: Piriformis Syndrome

The term “piriformis syndrome” refers to the piriformis muscle and the discomfort when the muscle irritates the sciatic nerve. The piriformis muscle is located in the lower spine, attaches to the thighbone, and aids with hip rotation. The sciatic nerve is located just below the piriformis muscle.

Sciatica may be caused by piriformis syndrome when the muscle spasms or gets inflamed. Inflammation may cause the muscle to enlarge and compress the sciatic nerve. At the same time, muscular spasms can affect individuals whose sciatic nerve passes through the muscle since the sciatic nerve is pinched when the muscle contracts.

It’s worth mentioning that piriformis syndrome might be challenging to identify and treat owing to the absence of X-ray or magnetic resonance imaging results. “Having a competent neurosurgeon or orthopedist do your physical examination will make all the difference in the world, given the normal X-rays and MRI scans that frequently accompany this source of sciatic nerve irritation,” Dr. Subach observes.

The Seventh Most Common Cause of Sciatica: Spinal Tumors

Spinal tumors are benign or malignant abnormal growths (cancerous). Cancerous tumors are often metastatic, meaning they have moved to the spine from another location in the body.

The following benign growths in the spine may compress the sciatic nerve:

Aneurysmal bone cysts (ABC). ABCs are not tumors, as the name implies, but blood-filled cysts that tend to grow rapidly.

Tumors with giant cells (GCT). GCTs are aggressive bone tumors that often target bones adjacent to joints, posing a significant hazard for the spine’s 364 joints.

Osteoid osteomas are a kind of osteoma. These tumors are located in bone and are typically modest in size. Once developed, they do not grow bigger. They may, however, result in the formation of new, unwanted bone in the afflicted region or osteoid bone around the tumor. Sciatica may arise as a consequence of nerve compression when a spinal tumor develops in  the lumbar area. Fortunately, spinal cancers are quite uncommon. “If medicine, physical  therapy, or injections do not alleviate your sciatic nerve discomfort, propose an MRI scan to  your pain management specialist or surgeon. It may prevent the possibility of an intraspinal—  that is, inside the spinal canal or column—cause of your discomfort,” Dr. Subach explains.  

What Are Some Less Frequently Occurring Causes of Sciatica?

Several lesser-known causes of sciatica include the following:

Endometriosis, a condition in which uterine tissue grows outside the uterus and can accumulate in areas surrounding the sciatic nerve or on the sciatic nerve itself;

Infection in the spine or spinal column, which causes an abscess to form and press on the sciatic nerve or causes nerve damage;

Nerve damage caused by diabetes;

Fetal shifts or growth during pregnancy, which can result in nerve compression.

Medication-related side effects

“Another typical type of traumatic injury is direct peroneal nerve damage,” Dr. Subach explains. “This often occurs due to a dislocated knee or a lower leg fracture and manifests as numbness in the back of the calf or ankle weakness while pointing the toes toward the shin. It seldom occurs in postoperative knee or hip replacement patients. In such circumstances, it is critical to rule out a spinal cause.”

Sciatica Risk Factors

Along with all of these possible causes of sciatica, anatomical, genetic, and lifestyle factors might combine to make you more sensitive to sciatic nerve pain. Several of these sciatica risk factors include the following:

Age: As you age, your chance of developing herniated discs and degenerative disc disease rises, which are two of the most prevalent causes of sciatica.

Obesity: Carrying an excessive amount of excess weight puts additional strain on the spine and increases pressure on the discs, resulting in herniation or other damage.

Employment and activities: Certain tasks are tough and physically demanding, requiring much lifting and twisting. Lifting and twisting improperly might significantly increase the risk of sciatica. On the other hand, some vocations need prolonged sitting, which may stress your discs, particularly if the prolonged sitting results in weaker core muscles and, therefore, less protection for your spine and discs.

Spinal cord injury: Prior injury might deteriorate discs, making them more prone to herniation and damage.

Sciatica: How Is It Treated?

Sciatica may often be treated at home with self-care. Applying cold packs, taking over-the- counter pain relievers/inflammatory reducers, and doing mild stretches all assist in lessening inflammation in and around the sciatic nerve or whatever is compressing it.

Additionally, your doctor may:

Prescribe medication, such as a muscle relaxant or pain reliever;

Recommend physical therapy to help relieve pressure on the nerve;

Suggest spinal injections near the affected nerve to reduce inflammation; and

Suggest alternative methods of relieving symptoms, such as acupuncture or yoga. Sciatica surgery is uncommon, but the most often performed treatments are a microdiscectomy, which eliminates part of a herniated disc, and a laminectomy, which removes part of a vertebra to provide more space in the spinal canal.

That concludes the discussion. Understanding what causes your sciatica enables you to cure it effectively. Obtaining a diagnosis and elucidating the source of your sciatica is the first step toward feeling better.


What triggers a flare-up of sciatica?

Sciatica may be caused by various conditions that impinge on the sciatic nerve or nerve root. This comprises herniated discs, spinal stenosis, and spinal damage. Frequently, a patient would “overdo” a slightly difficult job, such as gardening or box lifting. Restriction of exercise, applying ice to the low back region, and using an over-the-counter anti- inflammatory drug will often alleviate symptoms. After a few days, if the discomfort persists, contact your doctor.

What is the source of sciatica during pregnancy?

The lumbosacral plexus, a bundle of nerves, may get compressed between the fetus and pelvic bones during pregnancy. Additionally, extended time spent in the lithotomy position (with the hips and knees flexed and supported by stirrups) might result in sciatica.

Which vertebrae are responsible for sciatica?

Sciatica may originate from as high as the L4 (lumbar) vertebrae or as low as the S1 (sacrum) vertebrae. Each vertebra, including L5, has a matching nerve root that supplies the sciatic

nerve; symptoms may radiate in somewhat different directions depending on which root is involved.

Can worry and stress contribute to sciatica?

According to some studies, when you are anxious, your brain limits oxygen to the nerves in your lower back, resulting in sciatic pains. Additionally, cortisol (a stress hormone) may aggravate sciatica and prolong its duration.

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