What is Piriformis Syndrome?
Piriformis syndrome is a neuromuscular disorder that occurs when the sciatic nerve I compressed or otherwise irritated by the piriformis muscle causing pain, tingling, and numbness in the buttocks and along the path of the sciatic nerve descending down the lower thigh and into the leg.
Diagnosis is often difficult due to few validated and standardized diagnostic tests, but one of the most important criteria is to exclude sciatica resulting from compression/irritation of the spinal nerve roots, such as by a herniated disk. Piriformis syndrome may be due to anatomical variations in the muscle-nerve relationship, or from overuse or strain.
Uncontrolled studies have suggested theories about the disorder, however, a large-scale formal prospective outcome trial using Class A Study, designed as outlined by the American College of Physicians, found that the weight of the evidence-based medicine is that piriformis syndrome should be considered as a possible diagnosis when sciatica occurs without a clear spinal cause.
While 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 entrapment syndrome. Entrapment syndrome refers to sciatica symptoms not originating from spinal roots and/or spinal disk compression but involving the overlying piriformis muscle. In 15-30% of the population, the sciatic nerve passes through the piriformis muscle, rather than underneath it. These people have been reported by some studies to have a greater incidence of piriformis syndrome than the general population. Some researchers discount the importance of this relationship in the etiology of the syndrome.
Inactive gluteal muscles also facilitate the development of the syndrome. These are important in both hip extension and in aiding the piriformis in external rotation of the femur. A major cause for inactive gluteal muscles is unwanted reciprocal inhibition from overactive hip flexors (psoas major, iliacus, and rectus femorus). This imbalance usually occurs when the hip flexors have been trained to be too short and tight, such as when someone sits with their hips flexed, as in sitting all day at work. This deprives the gluteal muscles of activation, and the synergists to the gluteal muscles (hamstrings, adductor magnus, and the piriformis) then have to perform extra roles they are not designed to do. Resulting in hypertrophy of the piriformis then produces the typical symptoms.
Overuse injury resulting in piriformis syndrome can result from activities performed in the sitting position that involves strenuous use of the legs as in rowing/sculling and bicycling.
Runners, bicyclists, and other athletes engaging in forward-moving activities are particularly susceptible to developing piriformis syndrome if they do not engage in lateral stretching and strengthening exercises. When not balanced by lateral movement of the legs, repeated forward movement can lead to disproportionately weak hip abductors and tight adductors. Thus, disproportionately weak hip abductors/gluteus medius muscles, combined with very tight adductor muscles, can cause the piriformis muscle to shorten and severely contract. Upon a 40% increase in piriformis size, sciatic nerve impingement is inevitable. This means the abductors on the outside cannot work properly and strain is put on the piriformis.
The result of the piriformis muscle spasm can be the impingement of not only the sciatic nerve but also the pudendal nerve. The pudendal nerve controls the muscles of the bowels and bladder. Symptoms of pudendal nerve entrapment include tingling and numbness in the groin and saddle areas and can lead to urinary and fecal incontinence.
When piriformis syndrome is caused by weak abductors combined with tight adductors, a highly effective and easy treatment includes stretching and strengthening these muscle groups. An exercise regimen targeting the gluteus medius and hip adductor muscle groups can alleviate symptoms of piriformis syndrome within days.
Another purported cause for piriformis syndrome is stiffness, or hypomobility, of the sacroiliac joints. The resulting compensatory changes in gait would then result in shearing of one of the origins of the piriformis, and possibly some of the gluteal muscles as well, resulting not only in piriformis malfunction but in other low back pain syndromes as well.
Piriformis syndrome can also be caused by overpronation of the foot. When a foot overpronates it causes the knee to turn medially, causing the piriformis to activate to prevent over-rotating the knee. This causes the piriformis to become overused and therefore tight, eventually leading to piriformis syndrome.
Summary
By learning more about piriformis syndrome, we can better understand how to prevent and treat symptoms associated with it. When piriformis syndrome is present, whatever is required depends on the area affected and the symptoms present, and that is why it is important to have a team of doctors that is able to identify the root cause.
At BBC Health in Lewisville, Texas, we know how to identify, treat, or refer in the proper direction for any problems with your back, body, and spine. As a primary care provider, we can quickly provide medical, chiropractic, and rehab treatments in order to get you well as fast as possible. If you’re suffering from pain, don’t delay, and contact us immediately to see how we can help.
