Piriformis syndrome
Piriformis syndrome | |
---|---|
Other names | Deep gluteal syndrome |
Frequency | Unknown (2017)[4] |
Piriformis syndrome is a condition which is believed to result from
Causes may include trauma to the
Treatment may include avoiding activities that cause symptoms,
Signs and symptoms
The signs and symptoms include
Etiology
Causes of piriformis syndrome include the following
- Anatomic anomalies, present since birth:
- Bipartite piriformis muscle
- Sciatic nerve course/branching variations with respect to the piriformis muscle: In over 80% of the population, the sciatic nerve courses deep to and exits inferiorly to the piriformis muscle belly/tendon.[8][9] Early (proximal) divisions of the sciatic nerve into its tibial and common peroneal components can predispose patients to piriformis syndrome, with these branches passing through and below the piriformis muscle or above and below the muscle.[9][10]
- Acquired[11]
- Sitting for prolonged periods (office workers, taxi drivers, bicycle riders)
- Overuse syndromes: Piriformis muscle hypertrophy (viz., in athletes)
- Trauma to the hip or buttock area
Pathophysiology
When the piriformis muscle shortens or spasms due to trauma or overuse, it can compress or strangle the sciatic nerve beneath the muscle. Generally, conditions of this type are referred to as nerve entrapment or as
In 17% of an assumed normal population the sciatic nerve passes through the piriformis muscle, rather than underneath it; however, in patients undergoing surgery for suspected piriformis syndrome such an anomaly was found only 16.2% of the time leading to doubt about the importance of the anomaly as a factor in piriformis syndrome.[12]
MRI findings have shown that both hypertrophy (unusual largeness) and atrophy (unusual smallness) of the piriformis muscle correlate with the supposed condition.[13]
Piriformis syndrome may also be associated with direct trauma to the piriformis muscle, such as in a fall or from a
Diagnosis
Piriformis syndrome occurs when the sciatic nerve is compressed or pinched by the piriformis muscle of the hip. It usually only affects one hip at a given time, though both hips may produce piriformis syndrome at some point in the patient's lifetime, and having had it once greatly increases the chance that it will recur in one hip or the other at some future point unless action is taken to prevent it. Indications include sciatica (radiating pain in the buttock, posterior thigh, and lower leg) and the physical exam finding of tenderness in the area of the sciatic notch. If the piriformis muscle can be located beneath the other gluteal muscles, it will feel noticeably cord-like and will be painful to compress or massage. The pain is exacerbated with any activity that causes flexion of the hip including lifting, prolonged sitting, or walking.
The diagnosis is largely clinical and is one of
Wallet neuritis is an extra-spinal tunnel neuropathy of sciatic nerve, occurring mostly in men. Sitting down on a thick wallet in the back pocket produces uneven pressure in the hip region that impinges on the piriformis muscle and/or sciatic nerve. Wallet induced chronic sciatic nerve constriction produces gluteal and ipsilateral lower extremity pain, tingling, and burning sensation.[16]
Magnetic resonance neurography is a medical imaging technique that 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. However, magnetic resonance neurography is considered "investigational/not medically necessary" by some insurance companies. Neurography can determine whether or not a patient has a split sciatic nerve or a split piriformis muscle – this may be important in getting a good result from injections or surgery. Image guided injections carried out in an open MRI scanner, or other 3D image guidance can accurately relax the piriformis muscle to test the diagnosis. Other injection methods such as blind injection, fluoroscopic guided injection, ultrasound or EMG guidance can work but are not as reliable and have other drawbacks.
Prevention
The most common etiology of piriformis syndrome is that resulting from a specific previous injury due to trauma.[19] Large injuries include trauma to the buttocks while "micro traumas" result from small repeated bouts of stress on the piriformis muscle itself.[20] To the extent that piriformis syndrome is the result of some type of trauma and not neuropathy, such secondary causes are considered preventable, especially those occurring in daily activities: according to this theory, periods of prolonged sitting, especially on hard surfaces, produce minor stress that can be relieved with bouts of standing. An individual's environment, including lifestyle factors and physical activity, determine susceptibility to trauma of any given type. Although empirical research findings on the subject have never been published, many believe that taking sensible precautions during high-impact sports and when working in physically demanding conditions may decrease the risk of experiencing piriformis syndrome, either by forestalling injury to the muscle itself or injury to the nerve root that causes it to spasm. In this vein, proper safety and padded equipment should be worn for protection during any type of regular, firm contact (e.g. American football). In the workplace, individuals are encouraged to make regular assessments of their surroundings and attempt to recognize those things in their routine that may produce micro or macro traumas. No research has substantiated the effectiveness of any such routine, however, and participation in one may do nothing but heighten an individual's sense of worry over physical minutiae while have no effect in reducing the likeliness of experiencing or re-experiencing piriformis syndrome.[citation needed]
Other suggestions from some researchers and physical therapists have included prevention strategies including warming up before physical activity, practising correct exercise form,
Treatment
Immediate though temporary relief of piriformis syndrome can usually be brought about by injection of a local anaesthetic into the piriformis muscle.
Stretching
Most practitioners agree that spasm, strain or pain in any muscle can often be treated by regular stretching exercise of that muscle, no matter the cause of the pain. Stretching is recommended every two to three waking hours. Anterior and posterior movement of the hip joint capsule may help optimize the patient's stretching capacity.[26] The muscle can be manually stretched by applying pressure perpendicular to the long axis of the muscle and parallel to the surface of the buttocks until the muscle is relaxed.[27] Another stretching exercise is to lie on the side opposite the pain with the hip and knee of the upper leg flexed and adducted towards the ground while the torso is rotated so that the back of the upper shoulder touches the ground.[28] Physical Therapists may suggest stretching exercises that will target the piriformis but may also include the hamstrings and hip muscles in order to reduce pain and increase range of motion adequately. Patients with piriformis syndrome may also find relief by applying ice, which will help reduce inflammation and so may help limit pressure on the sciatic nerve. This treatment can be helpful when pain starts or immediately after an activity that is likely to cause pain.[citation needed] As the length of time progresses, heat may provide temporary relief from many types of muscle pain and will temporarily increase muscle flexibility.
Local injections
Failure of conservative treatments such as stretching and strengthening of the piriformis muscle or a high level of immediate pain intensity may bring into consideration various therapeutic injections such as local anesthetics (e.g.,
Surgery
For rare cases with unrelenting chronic pain, surgery may be recommended. Surgical release of the piriformis muscle is often effective. Minimal access surgery using newly reported techniques has also proven successful in a large-scale formal outcome published in 2005.[31] As with injections, the deactivated/ excised muscle's role in leg movement is completely compensated for by surrounding hip muscles.
Failure of piriformis syndrome treatment may be secondary to an underlying
Epidemiology
Piriformis syndrome (PS) data is often confused with other conditions
Piriformis syndrome is often left undiagnosed and mistaken with other pains due to similar symptoms with back pain, quadriceps pain, lower leg pain, and buttock pain. These symptoms include tenderness, tingling and numbness initiating in low back and buttock area and then radiating down to the thigh and to the leg.[35] A precise test for piriformis syndrome has not yet been developed and thus hard to diagnose this pain.[36] The pain is often initiated by sitting and walking for a longer period.[37] In 2012, 17.2% of low back pain patients developed piriformis syndrome.[36] Piriformis syndrome does not occur in children, and is mostly seen in women of age between thirty and forty. This is due to hormone changes throughout their life, especially during pregnancy, where muscles around the pelvis, including piriformis muscles, tense up to stabilize the area for birth.[34] In 2011, out of 263 patients between the ages of 45 to 84 treated for piriformis syndrome, 53.3% were female. Females are two times more likely to develop piriformis syndrome than males. Moreover, females had longer stay in hospital during 2011 due to high prevalence of the pain in females. The average cost of treatment was $29,070 for hospitalizing average 4 days.[32]
See also
References
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Further reading
- Jassal NS (2017). "Piriformis Muscle Syndrome". In Pope JE, Deer TR (eds.). Treatment of Chronic Pain Conditions. pp. 269–71. ISBN 978-1-4939-6974-6.