Piriformis Syndrome
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Last Updated: March 16, 2006
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Synonyms and related keywords: hip socket neuropathy, pseudosciatica, wallet sciatica, deep
gluteal syndrome, pyriformis syndrome
AUTHOR INFORMATION
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Author: Milton J Klein, DO, Consulting Staff, Department of Physical Medicine and Rehabilitation,
Sewickley Valley Hospital and Ohio Valley General Hospital
Milton J Klein, DO, is a member of the following medical societies: American Academy of Disability
Evaluating Physicians, American Academy of Osteopathy, American Academy of Physical
Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic
Medicine, American Medical Association, American Osteopathic Association, and American
Osteopathic College of Physical Medicine and Rehabilitation
Editor(s): Rajesh R Yadav, MD, Assistant Professor, Section of Physical Medicine and
Rehabilitation, MD Anderson Cancer Center, University of Texas at Houston; Francisco Talavera,
PharmD, PhD, Senior Pharmacy Editor, eMedicine; Michael T Andary, MD, MS, Residency
Program Director, Associate Professor, Department of Physical Medicine and Rehabilitation,
Michigan State University College of Osteopathic Medicine; Kelly L Allen, MD, Consulting Staff,
Department of Physical Medicine and Rehabilitation, Lourdes Regional Rehabilitation Center, Our
Lady of Lourdes Medical Center; and Consuelo T Lorenzo, MD, Consulting Staff, Department of
Physical Medicine and Rehabilitation, Alegent Health Care, Immanuel Rehabilitation Center
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[Lumbar
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and
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Myofascial Pain
Trochanteric
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INTRODUCTION
Section 2 of 10
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Pictures Bibliography
Background: Piriformis syndrome has remained a controversial diagnosis since its initial description
in 1928. Piriformis syndrome usually is caused by a neuritis of the proximal sciatic nerve. The
piriformis muscle can either irritate or compress the proximal sciatic nerve due to spasm and/or
contracture, and this problem can mimic a diskogenic sciatica (pseudosciatica).
Pathophysiology: The piriformis muscle is flat, pyramid-shaped, and oblique. This muscle
originates to the anterior of the S2-S4 vertebrae, the sacrotuberous ligament, and the upper margin
of the greater sciatic foramen (see Image 1). This muscle passes through the greater sciatic notch
and inserts on the superior surface of the greater trochanter of the femur. With the hip extended, the
piriformis muscle is the primary external rotator; however, with the hip flexed, the piriformis muscle
itself becomes a hip abductor. This muscle is innervated by branches from L5, S1, and S2. A lower
lumbar radiculopathy also may cause secondary irritation of the piriformis muscle, which may
complicate the diagnosis and hinder patient progress.
Many developmental variations of the relationship between the sciatic nerve in the pelvis and
piriformis muscle have been observed. In approximately 20% of the population, the muscle belly is
split with one or more parts of the sciatica nerve dividing the muscle belly itself. In 10% of the
population, the tibial/peroneal divisions are not enclosed in a common sheath. Usually, the peroneal
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portion splits the piriformis muscle belly; the tibial division rarely splits the muscle belly.
Involvement of the superior gluteal nerve usually is not seen in cases of piriformis syndrome. This
nerve leaves the sciatic nerve trunk and passes through the canal above the piriformis muscle.
Blunt injury may cause hematoma formation and subsequent scarring between the sciatic nerve and
short external rotators. Nerve injury can occur with prolonged pressure on the nerve or vasa
nervorum.
Etiology can be subdivided into a few categories as follows:




Hyperlordosis
Muscle anomalies with hypertrophy
Fibrosis (due to trauma)
Partial or total nerve anatomical abnormalities
Other causes can include the following:





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Pseudoaneurysms of the inferior gluteal artery adjacent to the piriformis syndrome
Bilateral piriformis syndrome due to prolonged sitting during an extended neurosurgical
procedure
Cerebral palsy
Total hip arthroplasty
Myositis ossificans
Vigorous physical activity
This syndrome remains controversial because, in most cases, the diagnosis is clinical, and no
confirmatory tests exist to support the clinical findings.
Papadopoulos et al proposed a new classification of piriformis syndrome. Primary piriformis
syndrome is for all intrinsic pathology of the piriformis muscle itself, such as myofascial pain,
anatomic variations, and myositis ossificans. Secondary piriformis syndrome (pelvic outlet
syndrome) includes all other etiologies of piriformis syndrome, with the exclusion of lumbar spinal
pathology.
Frequency:

In the US: Given the lack of agreement on exactly how to diagnose this condition, estimates
of frequency of sciatica caused by piriformis syndrome vary from rare to approximately 6%
of sciatica cases seen in a general family practice. Approximately 90% of adults have had at
least one episode of disabling low back pain (LBP) in their lifetime.
Mortality/Morbidity: Piriformis syndrome is not life-threatening, but it can have significant
associated morbidity. The total cost of LBP and sciatica is significant, exceeding $16 billion in both
direct and indirect costs.
Sex: Some reports suggest a 6:1 female-to-male predominance.
CLINICAL
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Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous
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History: Piriformis syndrome often is not recognized as a cause of LBP and associated sciatica.
This clinical syndrome is due to a compression of the sciatic nerve by the piriformis muscle. This
condition is identical in clinical presentation to LBP with associated L5, S1 radiculopathy due to
diskogenic and/or lower lumbar facet arthropathy with foraminal narrowing. Not uncommonly,
patients demonstrate both of these clinical entities simultaneously. This diagnostic dilemma
highlights the need for patients with LBP and associated radicular pain to undergo a complete
history and physical examination, including a digital rectal examination.
Many cases of refractory trochanteric bursitis are observed to have an underlying occult piriformis
syndrome due to the insertion of the piriformis muscle on the greater trochanter of the hip. If both the
trochanteric bursitis and the piriformis syndrome are treated inadequately, both conditions remain
resistant to medical management.
Physical: Examination findings may include the following:

Piriformis muscle spasm often is detected by careful deep palpation.

Digital rectal examination may reveal tenderness on lateral pelvic wall that reproduces
symptoms.

Reproduction of sciatica type pain with weakness is noted by resisted abduction/external
rotation (Pace test).

The Freiberg test is another diagnostic sign that elicits pain upon forced internal rotation of
the extended thigh.

The Beatty maneuver reproduces buttock pain by selectively contracting the piriformis
muscle. The patient lies on the uninvolved side and abducts the involved thigh upward; this
activates the ipsilateral piriformis muscle, which is both a hip external rotator and abductor
with the hip flexed.

A painful point may be present at the lateral margin of the sacrum.

Shortening of the involved lower extremity may be seen.

The patient may have difficulty sitting due to an intolerance of weight bearing on the buttock.

The patient may have the tendency to demonstrate a splayed foot on the involved side when
in the supine position.

Piriformis syndrome alone is rarely a cause of a focal neuromuscular impairment; either a
sciatic mononeuropathy or an L5-S1 radiculopathy can mimic both of these conditions,
obscuring diagnosis of piriformis syndrome.

A Morton foot may predispose the patient to developing piriformis syndrome. The prominent
second metatarsal head destabilizes the foot during the push-off phase of the gait cycle,
causing foot pronation and internal rotation of the lower limb. The piriformis muscle (external
hip rotator) reactively contracts repetitively during each push-off phase of the gait cycle as a
compensatory mechanism, leading to piriformis syndrome.
Causes: Approximately 50% of patients with piriformis syndrome have a history of trauma, with
either a direct buttock contusion or hip/lower back torsional injury. The remaining 50% of cases are
of spontaneous onset, so the treating physician must have a high index of suspicion for this problem,
lest it be overlooked.
DIFFERENTIALS
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[Lumbar Degenerative Disc Disease]
Lumbar Facet Arthropathy
Lumbar Spondylolysis and Spondylolisthesis
Myofascial Pain
Trochanteric Bursitis
Other Problems to be Considered:
Lumbosacral radiculopathy
Buttock pain
Ischial tuberosity bursitis
Sciatica
WORKUP
Section 5 of 10
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Bibliography
Lab Studies:
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Laboratory studies generally are not indicated in diagnosing piriformis syndrome.
Imaging Studies:
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Diagnostic imaging of the lumbar spine is mandatory to exclude associated diskogenic and/or osteoarthritic
contributing pathology.

Reports in the literature on piriformis muscle describe imaging by nuclear diagnostic studies and MRI of the
pelvis, but these tests are neither practical nor reliable diagnostic approaches to this problem. The history and
clinical diagnostic examination provide the greatest and most specific diagnostic yield for this problem.

Diagnostic ultrasound imaging of the piriformis muscle for assessment of muscle morphology has demonstrated a
significant correlation of piriformis muscle morphology abnormality, especially in patients with lumbosacral/buttock
pain and pain ascending stairs, referred pain to the posterior thigh on the symptomatic side, and reproduction of
pain with needling of the piriformis muscle.
Other Tests:

Results of electrodiagnostic testing for piriformis syndrome usually are normal. Reports of positional H-reflex
abnormalities can be found in the literature; however, such findings have not been widely accepted or
reproduced.
TREATMENT
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Rehabilitation Program:

Physical Therapy: Because a definitive method to accurately diagnose this problem is not available, treatment
regimens are controversial and have not been subjected to randomized blind clinical trials. Despite this fact,
numerous treatment strategies exist for patients with piriformis syndrome.
Functional biomechanical deficits may include the following:
o
o
o
o
o
Tight piriformis muscle
Tight hip external rotators and adductors
Hip abductor weakness
Lower lumbar spine dysfunction
Sacroiliac joint hypomobility
Functional adaptations to these deficits include the following:
o
o
o
Ambulation with thigh in external rotation
Functional limb length shortening
Shortened stride length
Once the diagnosis has been made, these underlying perpetuating biomechanical factors must be corrected.
Consider the use of ultrasound and other heat modalities prior to physical therapy sessions. Prior to performing
piriformis stretches, the hip joint capsule should be mobilized anteriorly and posteriorly to allow for more effective
stretching. Soft tissue therapies of the piriformis muscle can be helpful, including longitudinal gliding with passive
internal hip rotation, as well as transverse gliding and sustained longitudinal release with the patient lying on
his/her side. Addressing sacroiliac joint and low back dysfunction also is important.
A home stretching program should be provided to the patient. These stretches are an essential component of the
treatment program. During the acute phase of treatment, stretching every 2-3 hours (while awake) is a key to the
success of nonoperative treatment. Prolonged stretching of the piriformis muscle is accomplished in either a
supine or orthostatic position with the involved hip flexed and passively adducted/internally rotated.
Medical Issues/Complications: No consensus exists on overall treatment of piriformis syndrome due to lack of objective
clinical trials. Conservative treatment (eg, stretching, manual techniques, injections, activity modifications, modalities like
heat or ultrasound, natural healing) is successful in most cases.
Injection therapy can be incorporated if the situation is refractory to the aforementioned treatment program. For effective
injection, the piriformis muscle must be localized manually by digital rectal examination. Then the piriformis muscle is
injected using a 3.5-inch (8.9-cm) spinal needle. Care must be taken to avoid direct injection of the sciatic nerve.
Surgical Intervention: Surgical management is the treatment of last resort. Surgery for this condition involves resection
of the muscle itself or the muscle tendon near its insertion at the superior aspect of the greater trochanter of the femur (as
described by Mizuguchi). These surgical procedures are described as effective, and they do not cause any associated
superimposed postoperative disability.
Consultations:

Because of the enigmatic nature of piriformis syndrome, initial consultation obtained from an orthopedic surgeon
or similar specialist usually is nonspecific. This disorder is considered to be a soft tissue problem that presents as
low back or buttock pain with sciatica.

After all differential diagnoses have been excluded, consider piriformis syndrome. Due to the traumatic etiology of
most cases, piriformis syndrome usually is associated with other more proximal causes of LBP, sciatica, and
buttock pain (thereby further clouding the diagnosis).
Other Treatment (injection, manipulation, etc.):

The Spray N' Stretch myofascial treatment and ultrasound modality preceding physical therapy sessions are
useful.
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Manual muscle medicine, including facilitated positional release, may be helpful.

Injections with steroids, local anesthetics, and botulinum toxin type B (12,500 U) have been reported in the
literature for management of this condition. No single technique is universally accepted. Localization techniques
include manual localization of muscle with fluoroscopic and electromyographic guidance. The piriformis muscle,
after localization with a digital rectal examination, can be injected with a 3.5-inch (8.9-cm) spinal needle. Care
should be taken to avoid direct injection of the sciatic nerve.
FOLLOW-UP
Section 7 of 10
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Further Inpatient Care:
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Inpatient care would be necessary only if surgical intervention is warranted. Surgery is the last resort treatment for
severe cases of piriformis syndrome.
Further Outpatient Care:

Piriformis syndrome usually is treated effectively with conservative measures. Please refer to the Treatment
section for a discussion of treatment recommendations.
Deterrence/Prevention:

No method has been demonstrated to prevent piriformis syndrome. The best prevention is to maintain
biomechanical balance by restoration of a more physiologic weight bearing distribution with a level pelvis/sacral
base and equal leg lengths, achieved by heel lift therapy if necessary. This treatment approach also prevents
recurrences of piriformis syndrome, especially if the underlying etiology is a leg-length discrepancy. The patient
also must engage in a general stretching program that includes bilateral piriformis muscles.
Complications:

The most significant complication is failure to recognize, diagnose, and treat this disabling condition. If left
untreated, a patient may undergo unsuccessful back surgery for a disk herniation; however, a coexisting occult
piriformis syndrome can result in a failed back syndrome.

Another complication is inadvertent direct injection of the sciatic nerve, which usually results in a nondisabling and
temporary sciatic mononeuropathy.
Prognosis:

The prognosis depends upon early recognition and treatment. As this is a soft tissue syndrome, it has a tendency
to be chronic, usually due to late diagnosis and treatment and has a less favorable prognosis.
Patient Education:

For conservative measures to be effective, the patient must be educated with an aggressive home-based
stretching program to maintain piriformis muscle flexibility. He or she must comply with the program even beyond
the point of discontinuation of formal medical treatment.
MISCELLANEOUS
Section 8 of 10
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Medical/Legal Pitfalls:

The greatest medical/legal concern is either misdiagnosis or failure to diagnose piriformis syndrome. In most
cases, the diagnosis is one of exclusion. Therefore, if piriformis syndrome is not in the differential diagnosis list, it
may be overlooked. The patient becomes a chronic pain patient doomed to a lifetime of disability and chronic
management with medication.

Because the diagnosis usually is elusive, missing the diagnosis does not constitute malicious negligence and,
therefore, rarely would be sufficient grounds alone for a medical malpractice lawsuit.

Piriformis syndrome may be a secondary perpetuating factor underlying chronic posttraumatic intractable LBP.
Negligent misdiagnosis or delayed diagnosis of this condition has caused a significant degree of unnecessary
disability and financial loss.
Special Concerns:

In female patients, piriformis syndrome may be a cause of dyspareunia, but, again, this connection becomes
impossible to prove. Diagnosis of piriformis syndrome requires a high index of suspicion by either the primary
care physician or the obstetric/gynecologic specialist/surgeon. A bimanual simultaneous vaginal-rectal
examination of female patients to determine this soft tissue diagnosis helps the physician to prescribe appropriate
treatment.

Although it is a misdiagnosed etiology of LBP/sciatica, piriformis syndrome can be a significant cause of soft
tissue pain and disability. This problem requires a skillful, attentive physician to conduct a thorough
history/physical examination that provides an accurate diagnosis. Once the clinical diagnosis has been made, a
specific treatment can be formulated to provide the best outcome with a minimal degree of long-term disability.
PICTURES
Section 9 of 10
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Caption: Picture 1. Nerve irritation in the herniated disk occurs at the root
(sciatic radiculitis). In the piriformis syndrome, the irritation extends to the full
thickness of the nerve (sciatic neuritis).
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BIBLIOGRAPHY
Section 10 of 10
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Pictures
Bibliography
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Beatty RA: The piriformis muscle syndrome: a simple diagnostic maneuver. Neurosurgery 1994; 34: 512514[Medline].
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