Piriformis Syndrome

By admin On Oct 23, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Piriformis Syndrome

Douglas Comeau

Alysia L. Green

Basics

Description

Sciatic nerve irritation as it courses underneath or through the piriformis muscle causing buttock pain with or without radiation into the leg
The piriformis muscle acts as an external rotator in hip extension and an abductor in hip flexion.
Piriformis muscle spasm or hypertrophy can occur in certain motions, such as running downhill or repetitive motions.
Direct irritation of the sciatic nerve may be caused by inflammatory agents released from an injured piriformis muscle.
Synonym(s): Pyriformis syndrome; Sciatica; Sciatic neuritis; “Hip pocket neuropathy”; “Wallet neuritis”

Epidemiology

Incidence

6/100 cases of sciatica
Predominant gender: Female > Male (6:1 in some trials).
The incidence of piriformis syndrome is skewed secondary by the lack of evidence-based guidelines. The ratio is likely higher.

Risk Factors

In roughly 20% of the population, the sciatic nerve passes through the piriformis muscle, which may irritate the nerve and cause pain.
Leg-length discrepancy may predispose a patient to development of symptoms.
A Morton foot can predispose a patient from the change in ambulation.

General Prevention

Maintaining an appropriate lumbar core stabilization can decrease the recurrence of symptoms.
A core stabilization program includes the anterior pelvis, posterior back, and buttocks.

Etiology

The piriformis muscle originates at the S2–3 vertebrae, sacrotuberous ligament, and upper margin of the greater sciatic foramen.
The piriformis muscle then passes through the greater sciatic notch, inserting on the greater trochanter.
It is innervated by L5, S1, and S2.
In hip extension, the piriformis serves as an external rotator.
In hip flexion, it serves as a hip abductor.

Commonly Associated Conditions

Sciatica
Gluteal strain

Diagnosis

History

Trauma to the gluteal region is seen in <50% of patients.
Sitting on hard surfaces exacerbates pain.
Location of referred pain; not likely piriformis syndrome if below the knee
Complaint of pain with movements that cause external hip rotation
Women may complain of dyspareunia.

Physical Exam

Cramping or aching pain in the buttock ± pain radiating into the hamstrings
Sensation of “tight hamstrings”
Point tenderness to deep palpation over any part of the piriformis muscle
Pain increased with sitting
Full range of motion and 5/5 strength in active and passive forward flexion and extension
Negative stork test
Negative straight-leg raise and negative flexion, abduction, and external rotation
Buttock pain ± radiation to hamstrings produced by combination of hip flexion, adduction, and internal rotation; this maneuver stretches the piriformis muscle.
Pace sign: Weakness in resisted abduction and external rotation
Tenderness to palpation over the piriformis muscle
Sciatic notch tenderness
Usually normal neurologic examination
Pelvic and/or digital rectal examination elicits pain ipsilaterally proximal to the ischial tuberosity.

Diagnostic Tests & Interpretation

Lab

No laboratory tests are recommended in the workup.

Imaging

Diagnostic imaging is rarely helpful in confirming the diagnosis.
Clinical history and physical examination are key to diagnosing piriformis syndrome.
Further diagnostic tests may be needed to rule out other potential diagnoses.
MRI and CT scanning can be used if history and physical examination are not conclusive.
Atrophy or fibrous tissue replacement of the piriformis muscle on MRI or CT scan supports the diagnosis.
Musculoskeletal US demonstrating hypertrophy of the muscle is a newer radiologic technique that may be used in difficult cases.

Diagnostic Procedures/Surgery

Electromyographic (EMG) findings of peronaei and/or tibial H reflex prolongation in the adducted, internally rotated, flexed hip strongly anecdotally supports the diagnosis in some studies; however, EMG is typically normal and not a recommended diagnostic tool.

P.473

Differential Diagnosis

Lumbar facet arthropathy
Lumbar spondylolysis and spondylolisthesis
Lumbosacral radiculopathy
Myofascial pain
Achilles tendonitis
Cord tumor
Spinal stenosis
Aneurysm of the inferior or superior gluteal artery
Fibrotic band around the sciatic nerve
Hematoma
Gluteal abscess
Pelvic tumor
Endometriosis and other pelvic diseases
Bursitis: Obturator internus, trochanteric or ischial

Treatment

ED Treatment

Low back pain is one of the top 10 causes of acute emergency visits.
Typically, a lumbar spine film will be taken and is negative.
The patient should be treated with NSAIDs and muscle relaxants and sent for primary care and/or sports medicine follow-up.

Medication

First Line

NSAIDs for 10–14 days
Short course of analgesics and/or muscle relaxants may be beneficial (1)[C].
Ice
Acetaminophen

Additional Treatment

Additional Therapies

Relative rest for a short period, but should begin piriformis stretch and physical therapy as soon as possible
Physical therapy incorporating stretching and strengthening of the piriformis muscle; also should incorporate correction of pelvic obliquities and leg-length discrepancies (1)[A]
Deep muscle massage with US
Long-term treatment:
- Continued lumbar stabilization program
- Continued piriformis stretching
Injections:
- With no improvement after conservative therapy, consider local injection of anesthetic (1–2% lidocaine hydrochloride ± bupivacaine 4–6 mL) under fluoroscopic or US guidance into the tender area within the piriformis muscle.
- Botulinum toxin has shown benefit in nonrandomized, controlled trials. The mechanism of action would be decreasing the piriformis spasm by injecting Botox (2)[C].
Surgery as indicated earlier for recalcitrant cases of piriformis syndrome

Complementary and Alternative Medicine

Osteopathic manipulative treatment (OMT) may be used in conjunction with physical therapy.
Techniques include muscle energy technique and myofascial release to help with piriformis strengthening and stretching.

Surgery/Other Procedures

If conservative treatment fails, surgical release of the piriformis muscle around the sciatic nerve should be used as a last resort.
Patients with documented EMG nerve impairment have the best outcome after surgical release.

In-Patient Considerations

A patient typically is admitted only if preoperative for surgical correction.

Ongoing Care

Follow-Up Recommendations

Patient Monitoring

Initially, a patient should follow up with primary care or sports medicine 6–8 wks after starting physical therapy.
On follow-up, close interaction should be maintained to ensure compliance with the home exercise program (lumbar stabilization).

Patient Education

Patient education may include home exercise program handouts to ensure compliance.
Showing the patient a diagram of the piriformis and its closeness to the sciatic nerve may help in patient recognition.

Prognosis

Prognosis is predicated on compliance with home exercise program and core stability.
Although compliance with core stabilization cannot guarantee lifelong relief of symptoms, a stronger core can decrease the chance of recurrence.