It forms in the pelvis from nerves of the sacral plexus, and exits the greater sciatic foramen just underneath the piriformis.

The empirical evidence supporting this is that patients can often see immediate and permanent relief from local anesthetic and the effectiveness of Botox injections as a muscle relaxer.

[25] Or the formation of scar tissue from a hematoma might restrict normal movement of the sciatic nerve as it passes by the piriformis muscle.

[28] Piriformis syndrome does not yet have a validated set of diagnostic criteria,[4][29][11] however the diagnosis is primarily clinical, involving a physical examination and an evaluation of patient history.

[30] Imaging can assist in excluding other conditions with similar symptoms, such as lumbar disc herniation and spinal stenosis.

[29] A complete exam of low back, pelvis, buttocks, lower extremities may be necessary to rule out differential diagnoses.

[29] Sciatica secondary to conditions to be ruled out include spinal disc herniation, facet arthropathy, spinal stenosis, lumbar muscle strain, wallet neuritis[31] (sitting on a thick wallet), endometriosis, pelvic tumors, gluteal varicosities, and inferior gluteal artery aneuyrism.

[36] Both MRN and DTI can localize nerve lesions, their extension, and their spatial distribution due to conditions such as entrapment.

[43][44] While there is no gold standard test to diagnose piriformis syndrome,[2] in deep gluteal syndrome, the generalization of extra-spinal sciatica in the deep gluteal space, diagnostic blocks are considered the gold standard for differentiating alternate sources of pain.

[45] The most common etiology of piriformis syndrome is that resulting from a specific previous injury due to trauma.

[47] To the extent that piriformis syndrome is the result of some type of trauma and not neuropathy, such secondary causes are considered preventable, especially those occurring in daily activities: according to this theory, periods of prolonged sitting, especially on hard surfaces, produce minor stress that can be relieved with bouts of standing.

An individual's environment, including lifestyle factors and physical activity, determine susceptibility to trauma of any given type.

Although empirical research findings on the subject have never been published, many believe that taking sensible precautions during high-impact sports and when working in physically demanding conditions may decrease the risk of experiencing piriformis syndrome, either by forestalling injury to the muscle itself or injury to the nerve root that causes it to spasm.

In this vein, proper safety and padded equipment should be worn for protection during any type of regular, firm contact (e.g. American football).

In the workplace, individuals are encouraged to make regular assessments of their surroundings and attempt to recognize those things in their routine that may produce micro or macro traumas.

Stretching increases range of motion, while strengthening hip adductors and abductors theoretically allows the piriformis to tolerate trauma more readily.

[2] In a study of 42 patients with clinically suspected piriformis syndrome with normal MRI/CT imaging findings, 41 saw complete resolution of symptoms within 36 days.

[50] The goals of physical therapy are to reduce piriformis muscle tightness, improve spine/hip/pelvis mobility, and restore normal biomechanics to the spine/hip/pelvis.

[29] Massage is meant to break up trigger points, increase blood circulation, and lengthen the muscle fibers.

The exact benefits of physiotherapy for piriformis syndrome are unclear as well-designed, randomized trials are extremely limited.

[2][30] Ultrasound is a popular choice due to a balance of accuracy, accessibility, lack of radiation exposure, and affordability.

[29][2] The medications injected are local anesthetics (e.g. lidocaine, bupivacaine), corticosteroids, and Botulinum toxin (Botox, BTX), which may be used together or in combination.

[21][60] Comparing local anesthetic with corticosteroids against Botulinum toxin is difficult because existing studies tend to lack controls[60] which means that the effect of the treatment under observation is confounded with the natural history of the disease (patients with piriformis syndrome often see their symptoms resolve even without treatment).

[12] This is more common in women with a ratio of 3 to 1[70] and most likely due to the wider quadriceps femoris muscle angle in the os coxae.

[46] Between the years of 1991–1994, self-selecting patients seeking piriformis syndrome treatment from a group of American physicians had the following distribution: 75% were in New York, Connecticut, New Jersey, Pennsylvania; 20% in other American urban centers; and 5% in North and South America, Europe, Asia, Africa and Australia.

[71] The common ages of occurrence happen between thirty and forty, and are scarcely found in patients younger than twenty;[70] this has been known to affect all lifestyles.

These symptoms include tenderness, tingling and numbness initiating in low back and buttock area and then radiating down to the thigh and to the leg.

[74] In 2012, one study found that 17.2% of low back pain patients met a clinical diagnosis for piriformis syndrome.

[19] Advancements in medical technology like anesthesia, antibiotics, electrophysiology, imaging, image-guided injections, and surgery have revived interest around piriformis syndrome.

[21][20][78] Recently, advances in endoscopic surgery led to discoveries suggesting a broader classification was necessary to describe all the causes of sciatic nerve entrapment in the deep gluteal space.