What is the purpose of the piriformis (muscle) provocation test?

From the Guidelines

The piriformis provocation test is a valuable diagnostic tool for identifying piriformis syndrome, which is a common cause of extraspinal nerve entrapment, as noted in the 2021 update of the ACR Appropriateness Criteria for plexopathy 1. To perform this test, the patient lies on their back while the examiner flexes the patient's hip and knee to 90 degrees, then applies pressure over the piriformis muscle (located in the buttock region) while simultaneously rotating the hip internally. A positive test is indicated by reproduction of the patient's typical pain, particularly pain that radiates down the posterior thigh. This test works by stretching or compressing the piriformis muscle, which if inflamed or enlarged, will irritate the sciatic nerve running beneath or through it. Some key points to consider when using the piriformis provocation test include:

• The test is most useful when combined with other diagnostic maneuvers like the FAIR test (Flexion, Adduction, Internal Rotation) and a thorough patient history, as no single test for piriformis syndrome is definitive.
• When performing this test, it's essential to compare findings between the affected and unaffected sides to establish a baseline and confirm that the pain is indeed related to piriformis involvement rather than other causes of sciatica.
• The diagnosis of piriformis syndrome and other causes of lumbosacral plexopathy often relies on a combination of clinical evaluation, electrodiagnostic studies, and imaging, as outlined in the ACR Appropriateness Criteria 1.

From the Research

Piriformis Provocation Test

• The piriformis provocation test is used to diagnose piriformis syndrome, a condition characterized by pain in the buttock with variable involvement of the sciatic nerve 2, 3.
• The test is often performed in combination with other diagnostic methods, such as the modified flexion adduction internal rotation (FAIR) test, to confirm the diagnosis 2, 4.
• The FAIR test has been shown to have sensitivity and specificity of .881 and .832, respectively, in diagnosing piriformis syndrome 4.
• Other diagnostic methods, such as electrodiagnostic studies and ultrasound imaging, may also be used to support the diagnosis, but their sensitivity and specificity are unclear 3, 5.

Diagnostic Criteria

• The diagnosis of piriformis syndrome is often based on a combination of clinical features, including buttock pain, external tenderness over the greater sciatic notch, and aggravation of pain through sitting 3.
• The prevalence of piriformis syndrome is estimated to be 5%-6% in all cases of low back, buttock, and leg pain, and up to 17% of patients with chronic low back pain 2, 3.
• The diagnosis is often one of exclusion, due to the lack of consistent objective findings and the absence of a single test that is specific for piriformis syndrome 2, 3.

Treatment Options

• Treatment for piriformis syndrome typically involves conservative management, including physical therapy, stretching, and local anesthetic, botulinum toxin, and/or corticosteroid injections into the piriformis muscle or sciatic nerve sheath 3, 5, 6.
• Surgical interventions may also be used in some cases, but their effectiveness is variable 3, 4.
• Ultrasound-guided injection techniques have been shown to improve the accuracy of locating the piriformis muscle and may be a useful diagnostic and therapeutic tool 6.