Piriformis syndrome


Believed to result from compression of the sciatic nerve around the piriformis muscle.

Symptoms include pain and numbness in the buttocks and down the leg.

Symptoms often worsened with sitting or running.

Causes may include trauma to the gluteal muscle, spasms of the piriformis muscle, or an overuse injury.

There is no definitive test for diagnosis.

Physical exam maneuvers can be supportive to diagnosis.

Medical imaging is normal.

Differential diagnosis includes a herniated disc.

Treatment includes avoiding activities that cause symptoms, stretching, physiotherapy, and medication such as NSAIDs.

In patients who do not improve steroid or botulinum toxin injections may be used

Surgery is not typically recommended.

As the piriformis muscle shortens due to spasms from trauma or overuse, it can compress the sciatic nerve beneath the muscle.

The nerve entrapment that occurs in the piriformis syndrome refers to sciatica symptoms not originating from spinal root or disc compression, but involves the overlying piriformis muscle.

In about 17% of the population the sciatic nerve passes through the piriformis muscle, rather than underneath it.

Piriformis muscle hypertrophy and atrophy have increased risk for the syndrome.

It is suspected that people who regularly exercise but do not engage in lateral stretching and strengthening exercises may be at greater risk.

Repeated forward movements can lead to disproportionately weak hip abductors and tight adductors, when not balanced by lateral movement ofthe legs,

The piriformis syndrome can be caused by disproportionately weak hip abductors/gluteus medius muscles, combined with very tight adductor muscles, allowing the piriformis muscle to shorten and severely contract.

Some patients experiencing small spinal disc herniations which then impinge on the sciatic nerve and cause the piriformis to spasm secondarily.

The piriformis muscle spasm can impinge the sciatic nerve and the pudendal nerve.

The pudendal nerve controls the muscles of the bowels and bladder, and its entrapment can result in tingling and numbness in the groin and saddle areas, and can lead to urinary and fecal incontinence.

The syndrome may be associated with direct trauma to the piriformis muscle.

Significant injuries include trauma to the buttocks while mini traumas result from small repeated bouts of stress on the piriformis muscle itself.

Occurs when the sciatic nerve is compressed or pinched by the piriformis muscle of the hip, and usually only affects one hip at a time.

Both hips may have the piriformis syndrome at some point in a lifetime.

Experiencing the syndrome once greatly increases the chance that it will recur in one hip or the other at some future point.

The diagnosis is largely clinical.

Manifestations include sciatica with radiating pain in the buttock, posterior thigh, and lower leg.

The physical exam is associated with tenderness in the area of the sciatic notch.

If palpable beneath the other gluteal muscles, the pyriformis it will feel noticeably cord-like and will be painful to compress or massage.

Piriformis pain is exacerbated by action that causes flexion of the hip including lifting, prolonged sitting, or walking.

Piriformis syndrome is often mistaken with other pains due to similar symptoms with back pain, quadriceps pain, lower leg pain, and buttock pain.

Females are two times more likely to develop piriformis syndrome than males.

Diagnosis is one of exclusion.

Physical examination tests attempt may to stretch the irritated piriformis and provoke sciatic nerve compression.

Tests include the Freiberg test, the Pace test, the FABER test which applies flexion, abduction, and external rotation, and the FAIR test with flexion, adduction, and internal rotation.

Differential conditions include: herniated nucleus pulposus, facet arthropathy, spinal stenosis, and lumbar muscle strain.

MRI can show the presence of irritation of the sciatic nerve at the level of the sciatic notch where the nerve passes under the piriformis muscle.

Image guided injections can accurately relax the piriformis muscle to test the diagnosis.

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

Since the piriformis syndrome is the result of some type of trauma it is considered preventable.

Avoiding periods of prolonged sitting, taking sensible precautions during high-impact sports and when working in physically demanding conditions, wearing proper safety and padded equipment during any type of contact, warming up before physical activity, practicing correct exercise form, stretching, and doing strength training of hip adductors and abductors are all measures to be taken.

Temporary, but immediate relief of symptoms can usually be brought about by injection of a local anaesthetic into the piriformis muscle.

Conservative management usually begins with stretching exercises, massage, and avoidance of contributory activities.

Physical therapy, includes: soft tissue mobilization, hip joint mobilization, stretching techniques, and strengthening of the gluteus maximus, gluteus medius, biceps femoris to reduce strain on the piriformis, pelvic-trochanter isometric stretching, hip abductor, external rotator and extensor strengthening exercises, transcutaneous electrical nerve stimulation (TENS), and massage physiotherapy of the piriformis muscle region.

Despite the above recommendations the injury is considered largely self-limiting and spontaneous recovery is usually on the order of a few days or a week to six weeks or longer if left untreated.

Stretching is recommended every two to three waking hours.

Stretching exercises that target the piriformis, and include the hamstrings and hip muscles can reduce pain and increase range of motion

Ice may help reduce inflammation and limit pressure on the sciatic nerve, and can be helpful when pain starts or immediately after an activity that is likely to cause pain.

Later, heat may provide temporary relief from pain and will temporarily increase muscle flexibility.

Failure of conservative treatments or a high level of immediate pain intensity may bring consideration of therapeutic injections such as local anesthetics, anti-inflammatory drugs and/or corticosteroids, botulinum toxin, or a combination of the three, all of which have a well-documented effectiveness at relieving muscle-related pain.

The piriformis is a very deep seated muscle making injection with a paralyzing agent difficult without US or CT control.

A paralyzing agent can inactivate the piriformis muscle for 3 to 6 months, without resulting in leg weakness or impaired activity.

When the piriformis muscle becomes inactivated, the surrounding muscles quickly take over its role.

For rare cases associated with chronic pain, surgery may be recommended.

The surgical release of the piriformis muscle is often effective with minimal access surgery.

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