Piriformis Compression Test

Relevant Social Security Medical Listings

  • Listing 1.04      Disorders of the Spine (Adults)
  • Listing 101.04 Disorders of the Spine (Children)

Type

Subjective/Physical Examination (Sciatic Nerve)

Can SSA Purchase?

Yes, as part of physical examination.

Purpose

Diagnostic test for piriformis syndrome.

General

The sciatic nerve is the main nerve to the lower extremity, from which other nerves arise. The piriformis muscle lies very close to the sciatic nerve in the pelvis where they both pass through a bony opening called the greater sciatic foramen. Whereas the sciatic nerve branches down the leg, the piriformis muscle has one end attached to the upper, outer part of the femur.

Technique

In a supine position, the patient is evaluated in regard to a Straight Leg Raising (SLR) test, as well as other motions of the lower extremities: leg movement toward the midline of the body (adduction), away from the midline (abduction), internal rotation, and external rotation (see Range of Motion (ROM) Tests). These motions are to be tested passively, i.e., without effort or resistance on the part of the patient.

Interpretation

Sciatic nerve irritation can cause pain (sciatica). Sciatica caused by pressure on the sciatic nerve from a herniated intervertebral disk (HNP) tends to produce a positive SLR test, prominently involves the lower back, and may radiate the entire length of the lower extremity. This type of sciatica is what physicians usually check for in evaluating low back pain.

By contrast, the piriformis syndrome is caused by pressure on the sciatic nerve by the piriformis muscle. Sciatica caused by the piriformis syndrome occurs mainly in the buttocks, and is less likely to be associated with severe low back pain. The pain tends to be worsened by sitting and improved by standing and walking. Adduction and internal rotation of the lower extremity increase the pain of piriformis syndrome, because they bring the piriformis muscle up more tightly against the sciatic nerve. The presence of pain when these motions are reproduced on physical examination is known as a positive Freiberg’s sign. If there is pain and weakness on the affected side with contraction of the piriformis and active resistance to abduction and rotation of the hip, there is said to be a positive Pace’s sign. These maneuvers should not cause sciatic pain if due to an HNP.

As in sciatica caused by an HNP, a positive SLR test could result from piriformis syndrome since this maneuver also brings the piriformis toward the sciatic nerve. This fact could be a source of diagnostic error, particularly since most physicians do not consider piriformis compression of the sciatic nerve one of the diagnostic possibilities in evaluating sciatica with a positive SLR. However, some physicians do not believe the piriformis syndrome exists and the diagnosis remains somewhat controversial since the term “piriformis syndrome” was first used in 1947.