Sciatica vs. Piriformis Syndrome: How to Tell the Difference

Two Conditions, One Nerve — Different Origins

Buttock pain that radiates down the leg is commonly labelled "sciatica," but sciatica is a symptom, not a diagnosis. The sciatic nerve can be irritated at multiple points along its path, and correctly identifying the source changes the treatment completely. Two of the most frequently confused conditions are true lumbar radiculopathy (spinal sciatica) and piriformis syndrome — and they are treated very differently.

Anatomy: Where the Nerve Gets Compressed

Lumbar sciatica (radiculopathy) originates where the nerve roots that form the sciatic nerve exit the spinal canal at L4, L5, or S1. Compression here is most commonly caused by a herniated disc or foraminal stenosis narrowing the bony canal through which the nerve passes.

Piriformis syndrome originates in the deep buttock, where the sciatic nerve passes through or adjacent to the piriformis muscle. When the piriformis is hypertrophied, inflamed, or in spasm, it compresses the sciatic nerve in the infragluteal space — completely bypassing the spine.

Distinguishing Features: A Clinical Comparison

Why Piriformis Syndrome Is Frequently Missed

Standard lumbar MRI does not visualise the piriformis or the infragluteal space in detail. If a clinician orders an MRI looking for disc herniation, finds one at L4–L5, and stops there, they may attribute the patient's symptoms to the disc when the disc finding is incidental and the real pain generator is the piriformis. Studies suggest 20–35% of adults have identifiable lumbar disc bulges on MRI with no symptoms — the disc is not automatically the culprit just because it is visible.

A thorough clinical examination that includes hip rotation testing, palpation of the greater sciatic notch, and the FAIR test is essential to avoid this diagnostic shortcut.

Structural Causes of Piriformis Syndrome

The piriformis does not spontaneously go into spasm without reason. Contributing structural factors include:

• Pelvic obliquity or sacroiliac joint dysfunction — alters the tension and resting position of the piriformis
• Leg length discrepancy — changes gait mechanics, overloading the hip on the longer-leg side
• Weak hip abductors and external rotators — shifts load to the piriformis as a compensatory stabiliser
• Prolonged sitting — compresses the piriformis directly and shortens hip external rotators

Treatment Implications

This distinction matters enormously for treatment:

Lumbar sciatica responds to lumbar traction and decompression, specific adjustments to the affected level, and exercises that reduce disc pressure (extension-based protocols for posterolateral herniations).

Piriformis syndrome responds to piriformis-specific stretching (the figure-four stretch is most effective), deep soft-tissue work to the piriformis and obturator muscles, and correction of the underlying pelvic or hip mechanics driving the problem.

Treating piriformis syndrome with lumbar protocols — or vice versa — produces weeks of frustrating non-response. An accurate structural diagnosis is the foundation of efficient recovery.