Piriformis syndrome: what it is, anatomy, causes, symptoms, treatment and prevention

Piriformis syndrome: what it is, anatomy, causes, symptoms, treatment and prevention

The piriformis syndrome or pyramidal muscle is a pathology affecting the piriformis muscle, located between the pelvis and the femur, which gives rise to a cascade of structural and physiological changes. The symptoms of inflamed piriformis muscle have many similarities to other conditions involving the spine. Hence, this is the reason for the difficulty of diagnosis.

In fact, the most common are: pain in the buttock area, tingling in the foot and “shocks” in the back of the leg, symptoms that are also common in other pathologies.

But in the most serious cases, the symptoms can lead to a significant deterioration in the quality of life.

How to heal from inflamed piriformis? Conservative therapy combined with pharmacological therapy can lead to a resolution of the problem. In fact, only in rare cases will surgery be opted for.

However, in the resolution phase of the syndrome, prevention is necessary to avoid relapses and exacerbations of pain.

What is piriformis syndrome

Piriformis syndrome is a condition in which the piriformis muscle (located at the back of the pelvis) can compress the sciatic nerve, causing pain in the buttock area, and sometimes extend to the sciatic nerve, causing sciatica.

It is quite rare, but causes symptoms such as buttock spasms and pain that can involve the nearby sciatic nerve, causing numbness, weakness and tingling down the back of the leg and in the foot.

According to studies, there is a greater tendency for the syndrome to develop among women. In fact, hormonal changes, the menstrual cycle and pregnancy can be factors that more or less directly affect the function of the pelvis and, consequently, the piriformis muscle. Furthermore, according to the data, about 5-8% of episodes of low back pain seem to be caused precisely by the piriformis syndrome, while 15% of the cases examined suffered from it at least once in their life.


Piriformis: hints of anatomy

The piriformis, or pyramidal, muscle is a small muscle found in the buttock area, originating from the anterior face of the sacrum and inserts on the femur. Thus, we can imagine it as a thin, downward sloping muscle resembling a triangle shape.

But this muscle has one peculiarity. Indeed, it is in close contact with the sciatic nerve and is potentially capable of compressing the nerve with its muscle fibers.

It performs the primary function of extra rotation of the leg but also participates in its abduction beyond 60 degrees of flexion and stabilizes the femur when the limb is under load.

Therefore, participating in an important way in the stabilization of the femur, therefore of the hip, it could face overloads that can have repercussions on the whole pelvis area (locally) and on the whole posture.

Therefore, this muscle remains a special watch in all people with pelvis and hip problems, but also in sportsmen.

Piriformis syndrome: causes

The causes of piriformis syndrome are not entirely clear and there are several hypotheses. The piriformis is an ever-moving muscle whose irritation can be caused by too much sedentary lifestyle, long periods of inactivity or excessive exercise.

Therefore, an incorrect and frequent solicitation, for example, a postural compensation, can lead to a biomechanical change of the joints between the pelvis and the foot. The piriformis, being the muscle of union between the femur and the pelvis, is in fact directly affected by these changes. A sporting example is running. In fact, a technically incorrect run or unsuitable shoes could lead to postural defects and excessive stress on the piriformis muscle. From a biomechanical point of view, the piriformis is influenced by every postural and joint change in the body, more directly from the lower limbs. Thus, it can be argued that piriformis syndrome basically has secondary causes. Instead, among the primary causes are direct traumas that give rise to edema and create mechanical pressure on the sciatic nerve.

The most likely causes of piriformis syndrome therefore may be:

  • Contracture and tension of the piriformis muscle and tendon.
  • Running and other repetitive activities that place excessive strain on the muscle and which can cause the piriformis to contract.
  • Sitting for too long.
  • Lift heavy objects.
  • Climb stairs often.
  • Direct trauma and muscle injury.
  • Bone, muscle and nerve anatomical abnormalities.
  • Trauma injuries and accidents.

Risk factors

A sedentary lifestyle and sedentary work can lead to the development of piriformis syndrome. Above all, the sitting position in the car leads the piriformis to a situation of suffering which, if continued over time, can lead to disabling symptoms.

However, as with any musculoskeletal disease and problem, there is a basis of genetic or anatomical predisposition.

But in the case of piriformis syndrome, the anatomical predisposing factor is the point of passage of the sciatic nerve in the piriformis muscle area. In fact, in some people, the sciatic nerve literally pierces or passes over the piriformis muscle. It has been shown that in these conditions the risk of entrapment of the sciatic nerve is higher than in the passage of the nerve below the piriformis muscle.

Piriformis syndrome: symptoms

The symptoms of piriformis syndrome can easily be confused with other pathologies such as herniated discs or changes in the vertebral structure.

Therefore, monitoring pain by marking painful areas, intensity and related changes during the day is important to help the doctor in the diagnosis.

The classic symptom of piriformis syndrome is pain in the buttocks. The pain intensifies with maintaining a sitting position for about 15 minutes, especially while sitting. Increased pain and spasm of the piriformis muscle lead to compression of the sciatic nerve.

Thus, people with piriformis syndrome may complain of radiating pain in the buttock that travels down the back of the thigh, usually to behind the knee. The feeling of numbness can sometimes reach down to the toes.

The pain is usually continuous but varies in intensity. Thus, it can worsen in the sitting position but also in the static standing position and in the internal rotation of the leg.

Movement and change of posture can decrease the intensity of the pain but usually an unpleasant and painful sensation continues to persist.

This leads to difficulty walking or crossing your legs when sitting.

Pain in piriformis syndrome

The causes of pain triggered by piriformis syndrome are of different types. Nerve-type pain is caused by compression of the sciatic nerve, in the buttock area and with a sciatic course. It is a “shock” type pain that starts from the gluteal area and radiates to the back of the thigh and leg.

But pain related to nerve compression is associated with muscle suffering, caused by the activation of a “muscle fiber knot” in the buttock area which also affects local circulation. In this case, although rarely, the pudendal nerve, which innervates the entire pelvic floor, may also be involved.

Finally, there is pain in the sacroiliac area, the joint between the pelvis and sacrum. It is a joint with very few degrees of movement but also very important.

It is therefore the consequence of the inflammatory state triggered by the suffering of the nerve which, by releasing inflammatory chemical mediators, would give rise to the painful syndrome.

Piriformis syndrome: diagnosis

The symptomatology is similar to that of a classic sciatica, for this reason the piriformis syndrome can be defined as “false sciatica”. Therefore, it is important to exclude any other pathology, for example herniated disc, with an accurate differential diagnosis.

That said, the first step in diagnosing piriformis syndrome is therefore to make a differential diagnosis, i.e. to exclude any pathologies that have similar symptoms. They are usually pathologies affecting the spine, pelvis and lower limbs.

The clinical evaluation proceeds with some clinical tests and diagnostic tests.

Clinical trials

The Freiberg test has the objective of stretching the fibers of the piriformis muscle, if their stretching is painful we can affirm the positivity of the test. It is performed with the subject on his stomach (prone) on the couch, the leg is passively flexed up to 90°, subsequently imparting an internal rotation of the femur. Going precisely to stretch the piriformis muscle.

Instead, Pace and Nagle’s test involves active patient intervention. From the seated position, feet resting on the ground, the patient tries to spread his legs by pushing against the operator’s hands. This will also create an isometric contraction of the piriformis muscle. Therefore, the positivity of the test will be given by the perception of muscle pain and a sensation of compression in the gluteal area.

Generally we proceed with instrumental tests. The classic, and often overused, x-rays (RX) are usually the first indication of investigation. However, they are useful for analyzing the bone structures of the spine and pelvis.

MRI and CAT scan

A second level of investigation is represented by magnetic resonance imaging (MRI), which highlights any problems affecting the soft tissues and bone structure.

Computed tomography (CT), the old CAT scan, is another…