Dr. Yi-Cheng Wu
中文

What You Think Is Piriformis Syndrome May Actually Be Deep Gluteal Syndrome

By Dr. Yi-Cheng Wu · Reviewed June 21, 2026

Many cases of buttock pain and sciatica labelled as piriformis syndrome are actually part of the broader deep gluteal syndrome, and most can be managed conservatively at first with stretching, physical therapy, and core training.

Piriformis syndrome refers to compression or irritation of the sciatic nerve as it passes near the piriformis muscle, causing buttock pain that sometimes radiates to the back of the thigh. It accounts for roughly 6% to 8% of sciatica cases, with an average age of onset around 38 and a female predominance. Recent research favours the term deep gluteal syndrome, because in addition to the piriformis, other hip rotator muscles and anatomical variations of the sciatic nerve can also compress the nerve. Diagnosis rests mainly on history and physical examination, and about six weeks of conservative treatment (NSAIDs, stretching, physical therapy, and core stability work) is generally recommended before considering imaging or injection. Whether a given treatment is suitable, and what to do, still depend on your condition and a physician's individual assessment.

Piriformis syndrome refers to compression of the sciatic nerve by the piriformis muscle and is estimated to account for 6% to 8% of all cases of sciatica. It was first described in 1928, and the term piriformis syndrome was first introduced in 1947. Piriformis syndrome has now been described for nearly a century, yet the diagnosis remains a source of debate and confusion.

Recent research suggests that the term deep gluteal syndrome may better describe the condition. For ease of reading and understanding, however, this article still refers to it as piriformis syndrome.

Piriformis syndrome refers to irritation of the sciatic nerve as it passes through or beneath the piriformis muscle, causing buttock pain that may be accompanied by radiation into the leg. The sciatic nerve can be irritated directly by inflammatory mediators released from an injured piriformis muscle.

The piriformis acts as an external rotator when the hip is extended and as an abductor when the hip is flexed. Spasm or hypertrophy of the piriformis can occur with certain movements, such as downhill running or repetitive activities.

Epidemiology

  • Incidence: about 6 per 100 cases of sciatica. Many cases of sciatica are not caused by the piriformis, but many people mistakenly equate sciatica with piriformis syndrome.
  • Average age: 38 years
  • Predominant sex: more common in women than men (a ratio of 6:1 in some studies)
  • Because the incidence of piriformis syndrome lacks strong evidence-based confirmation, the actual proportion may be higher.

Aetiology and pathophysiology

  • The piriformis originates from the S2-S3 vertebrae, the sacrotuberous ligament, and the upper margin of the greater sciatic foramen; it then passes through the greater sciatic notch and inserts on the upper border of the greater trochanter.
  • It is innervated by the L5, S1, and S2 nerves.

Risk factors

  • In about 20% of people, the sciatic nerve passes through the piriformis, which can irritate the nerve and cause pain. Research describes six different anatomical variations between the sciatic nerve and the piriformis, and some variant patterns may carry a higher likelihood of developing piriformis syndrome. The piriformis is not the only muscle that can compress the sciatic nerve — several other hip rotator muscles can too, which is why deep gluteal syndrome is a more fitting term.

  • Variation in where the piriformis attaches may also play a role: only 53.6% of the tendons show the traditional anatomy, inserting on the upper border of the greater trochanter.

  • A leg-length discrepancy may make a person more prone to symptoms, and a Morton toe (a second toe longer than the big toe) may make a person more susceptible because of altered gait.

History

  • Fewer than 50% of patients have a history of buttock trauma.
  • Buttock pain that may be accompanied by radiation into the leg, worsened by sitting on a hard surface.
  • If the pain is below the knee, piriformis syndrome is less likely.
  • Women may report symptoms of pain with intercourse (dyspareunia).

Physical examination

  • Pain presents as cramping or aching in the buttock that may radiate to the back of the thigh and feel like a tight hamstring.
  • Tenderness on deep palpation of the piriformis.
  • Pain may worsen when sitting.
  • Hip range of motion and strength are not greatly affected.
  • With combined hip flexion, adduction, and internal rotation, buttock pain may radiate to the hamstring.
  • A pelvic and/or rectal examination may provoke pain near the ipsilateral ischial tuberosity.

Diagnostic tools

  • Clinical history and physical examination are the key to diagnosing piriformis syndrome.
  • X-ray: lumbar and pelvic X-rays are usually normal.
  • Neuromuscular ultrasound: helps assess piriformis hypertrophy and the condition of the sciatic nerve.
  • Electromyography (EMG): with the hip in internal rotation and flexion, prolongation of the H reflex of the peroneal and/or tibial nerve has been considered supportive of the diagnosis in some studies; however, EMG in piriformis syndrome is usually normal, and it is not a recommended diagnostic tool.
  • Magnetic resonance imaging (MRI): can help with diagnosis, but in the absence of clear symptoms MRI is not recommended, because many patients with sciatica do not show muscle hypertrophy on MRI, and among reports where muscle hypertrophy was seen on MRI, 19% were in asymptomatic patients.
  • A six-week course of conservative treatment is recommended first. If symptoms persist beyond six weeks, MRI can then be considered; atrophy or increased fibrous tissue in the piriformis seen on MRI or CT can support the diagnosis.

Initial treatment

  • Nonsteroidal anti-inflammatory drugs (NSAIDs) and muscle relaxants may be used for 3-10 days; short-term medication use may be beneficial.

  • Relative rest in the short term, but piriformis stretching and physical therapy should begin as soon as possible. Physical therapy includes stretching and strengthening of the piriformis, correcting the effects of pelvic obliquity and leg-length discrepancy, and deep muscle massage combined with ultrasound therapy.

  • Long-term treatment: ongoing lumbar core stability training and piriformis stretching.

  • If there is no improvement after conservative treatment, injection of a local anaesthetic (4-6 ml) into the painful area of the piriformis can be considered, with the option of adding a corticosteroid.

  • The accuracy of ultrasound-guided injection is 95%.

  • In the related research, after injection 15% had complete relief with no recurrence of pain, 8% obtained 2-4 months of relief after a repeat injection, 37% obtained 2-4 months of relief followed by recurrence, 24% obtained less than 2 weeks of relief followed by recurrence, and 16% obtained no relief.

  • Botulinum toxin has shown possible benefit in randomized, double-blind, controlled trials; the mechanism is a reduction in piriformis spasm through the injection of botulinum toxin.

Surgery

  • If conservative treatment fails, surgical release of the sciatic nerve around the piriformis is a last resort. Patients with documented EMG evidence of nerve compromise tend to do better after surgical release.
  • Patients should be encouraged to bear weight as tolerated within 5 to 10 days after surgery and to gradually return to full activity; avoiding prolonged sitting is recommended for 4 to 6 weeks after surgery.

Prognosis

  • Prognosis depends on the exercise program and the degree of core stability. A core training program does not guarantee lifelong relief of symptoms, but a stronger core can lower the chance of recurrence.
  • A lack of early diagnosis and treatment tends to lead to more complications.

References

Frequently asked questions

Is piriformis syndrome common, and who is more likely to develop it?

Studies estimate it accounts for about 6% to 8% of sciatica cases, with an average age of onset around 38 and a female predominance. It is worth noting that many cases of sciatica are not caused by the piriformis, so the two should not be treated as the same thing.

Why do some people say it should be called deep gluteal syndrome instead?

Because the piriformis is not the only muscle that can compress the sciatic nerve — several other hip rotator muscles can too, and there are multiple anatomical variations in how the sciatic nerve relates to the piriformis. For these reasons, deep gluteal syndrome is considered a better description of the overall condition.

What symptoms does piriformis syndrome usually cause?

The typical picture is buttock pain or cramping that may radiate to the back of the thigh and feel like a tight hamstring, worsening with prolonged sitting or sitting on a hard surface. If the pain extends below the knee, it is less likely to be piriformis syndrome.

What tests are needed to confirm the diagnosis?

Clinical history and physical examination are the key to diagnosis, and X-rays are usually normal. Neuromuscular ultrasound and, when needed, MRI can help with assessment, but muscle hypertrophy can also be seen on imaging in people without symptoms, so imaging must be interpreted together with the clinical picture.

This article is also available in the original Chinese, with the full reference list.

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