Piriformis syndrome irritates the sciatic nerve in the buttock

The piriformis muscle sits next to the sciatic nerve deep in the buttock

The piriformis muscle attaches to the front of the sacrum, the bone at the base of your spine, and to the bony point at the top of the thigh bone called the greater trochanter ^[2]. The sciatic nerve usually leaves the pelvis beneath this muscle ^[2].

In some people the nerve passes through the muscle or above it, or splits around it. These variations can make the nerve easier to squeeze ^[2]. A review of the anatomy research found that only some of these variations were clearly identified as a cause of the syndrome ^[5].

Injury may also play a role. About half of people with the condition report a past blow or twisting injury to the buttock ^[2]. In a review of published case reports, 38.2% of people had a history of pelvic trauma or muscle stress from vigorous activity or sport ^[3].

In that same review, an anatomical variant of the muscle or nerve was the most frequent cause found. Even so, nearly half of the people had no finding at all ^[3].

Piriformis syndrome causes buttock pain that may travel down the leg

The main symptom is pain in the buttock, and it often gets worse in certain positions ^[2]. The signs described in the research include:

• Pain in the buttock that may radiate into the leg ^[1].
• Pain that gets worse with long sitting or certain hip movements ^[2].
• Pain that stands out when getting out of bed, or when turning or bending the hips ^[2].
• Discomfort that may start at the back of the thigh and travel into the lower leg ^[2].

It commonly affects people in their fourth or fifth decade of life, regardless of job or activity level ^[2]. One review reported a higher rate in women ^[2].

Ordinary sciatica is often described as sharp, burning pain down the back of the leg. Its most common cause is a disc, the soft cushion between spine bones, pushing out ^[4]. Because the two can feel alike, piriformis syndrome is hard to tell apart from spine problems ^[2].

Clinicians disagree about how often piriformis syndrome causes sciatica

The numbers differ, and one review notes there is no agreed standard for diagnosing it ^[2]. Some authors say it is frequently underdiagnosed because its symptoms overlap with spine, sacroiliac joint, and hip problems ^[1]. Others say it is commonly mistaken for other ailments and that true piriformis-related sciatica is relatively rare ^[2].

For comparison, one review reported that disc disease is associated with 85% of sciatica cases ^[3]. The same review estimated about 2.4 million cases of piriformis syndrome per year in the United States ^[3].

Doctors assess piriformis syndrome mainly through symptoms and a physical exam

No single reliable exam or test confirms piriformis syndrome ^[2]. Diagnosis is typically supported by your description of your symptoms and a physical exam ^[2].

• A tender or tight piriformis muscle ^[2].
• A positive FAIR test, which bends the hip, moves the leg across the body, and turns it inward ^[2].
• Pain that is reproduced by maneuvers known as the Pace sign and the Freiberg sign ^[2].
• A pattern of buttock pain, pain worse when sitting, tenderness near the greater sciatic notch, and pain with movements that stretch the muscle and limit straight leg raising ^[3].

Standard imaging often looks normal. MRI and CT scans mainly help rule out other problems, such as a herniated disc or arthritis of the spine joints ^[2]. A specialized nerve scan called magnetic resonance neurography can show inflammation of the sciatic nerve ^[2].

Some clinicians accept a numbing injection into the muscle as a reference test. It still lacks strong validation and is not standardized ^[2]. In a review of published cases, surgery was more likely to fail when the diagnosis was made without any imaging or surgical finding ^[3].

Nonsurgical care comes first when piriformis syndrome is treated

First-line care includes physical therapy, anti-inflammatory medicines called NSAIDs, injections, and lifestyle changes ^[1]. In a review of published cases, nonsurgical care worked for 41.1% of people, and 58.9% went on to surgery ^[3]. Published cases may not represent everyone with the condition.

Results of injections appear to depend on how the nerve lies in relation to the muscle and on how precisely the injection is guided ^[6].

Up to 20% to 30% of people develop refractory piriformis syndrome, meaning pain that persists after at least 3 months of optimized nonsurgical treatment ^[1]. Surgery to release the muscle tendon or free the nerve may then be needed ^[1]. Endoscopic decompression is a minimally invasive alternative to open surgery. Complication rates in pooled studies ranged from 0% to 12% and were mostly minor ^[1].

Because surgery on the sciatic nerve carries risks, the authors of one review advise trying all nonsurgical treatments first ^[3].

Sciatica usually improves within weeks to months with simple home care

Sciatica in general usually gets better in a few weeks to a few months. It can last longer, and it can return ^[4]. These steps are described for sciatica as a whole, not only for piriformis syndrome.

• Carry on with normal activities as much as possible ^[4].
• Start gentle exercise as soon as you can, since anything that gets you moving can help ^[4].
• Hold heat packs to the painful areas ^[4].
• Avoid sitting or lying down for long periods. Even if moving hurts, it is not harmful and can help you get better faster ^[4].

See your primary care doctor if your symptoms have not improved after a few weeks of home treatment, or if they stop you doing your normal activities ^[4]. A physical therapist can offer exercise advice and hands-on techniques such as massage ^[4].