Sciatica / Radiating Leg Pain Explained:

Common Conditions We Treat (and Why They Happen)

Sciatica is not a diagnosis—it’s a symptom. It describes pain, numbness, tingling, or weakness that travels from the lower back or buttock down the leg, following the path of the sciatic nerve—the largest nerve in the body. True sciatica results from irritation or compression of the sciatic nerve or one of the nerve roots that forms it, and it can range from a mild, intermittent ache to a severe, debilitating burning or electric sensation that makes sitting, standing, or walking extremely difficult. Understanding the source of that irritation is what determines the most effective treatment.

Lumbar Disc Herniation as a Cause

The most common cause of true sciatica is a herniated disc in the lumbar spine—particularly at the L4-L5 or L5-S1 levels—where the extruded disc material presses against the nerve root that forms part of the sciatic nerve. The resulting inflammation and mechanical pressure produce the characteristic radiating symptoms. Disc-related sciatica is often worsened by sitting, forward bending, and activities that increase pressure within the disc, and may improve with walking or certain positional changes.

Piriformis Syndrome

The sciatic nerve passes through or directly beneath the piriformis muscle in the buttock region. When this muscle becomes tight, inflamed, or goes into spasm—from overuse, prolonged sitting, or trauma—it can compress the sciatic nerve and produce symptoms nearly identical to disc-related sciatica. This is an important distinction: piriformis syndrome is a soft tissue problem, not a spinal one, and it responds very differently to treatment. It’s also frequently misdiagnosed as a lumbar disc issue, particularly when imaging of the spine appears normal.

Lumbar Spinal Stenosis

Stenosis refers to a narrowing of the spinal canal or the openings through which nerve roots exit the spine. When this narrowing compresses the sciatic nerve roots, it produces neurogenic claudication—leg pain, heaviness, and fatigue that worsens with standing or walking and relieves with sitting or forward bending. Stenosis-related symptoms tend to be bilateral (affecting both legs) and are more common in older adults due to degenerative changes in the spine.

Sacroiliac Joint Referral

The sacroiliac joint can refer pain into the buttock and posterior thigh in a pattern that closely mimics sciatica, though true neurological symptoms (numbness, tingling, or weakness below the knee) are not typically produced by SI joint dysfunction alone. Distinguishing between SI joint referral and true nerve compression is important because the two conditions require fundamentally different approaches.

True Nerve Compression vs. Referred Pain: Why It Matters

Not all leg pain is sciatica, and not all sciatica comes from the same source. Referred pain from muscles, joints, or trigger points can travel into the leg without involving nerve compression at all—and it requires a completely different treatment strategy. True radiculopathy (nerve root compression) produces specific neurological symptoms: dermatomal numbness, myotomal weakness, and diminished reflexes in a predictable pattern that corresponds to the affected nerve level. Accurate differentiation between these presentations is one of the most clinically important assessments in low back and leg pain care.

The Bottom Line

Sciatica can be one of the most disabling pain patterns a person experiences, but the majority of cases—regardless of cause—respond well to conservative care when the source of nerve irritation is correctly identified. Chiropractic adjustments to reduce mechanical compression, soft tissue work to release muscular contributors like the piriformis, and specific nerve mobilization techniques can dramatically reduce symptoms and restore function. The goal is always to resolve the cause of nerve irritation, not simply manage the pain it produces.