What is Piriformis Syndrome (buttock pain, siatica)

Introduction

Piriformis syndrome is caused by the irritation or compression of the sciatic nerve at the a piriformis muscle.  This syndrome is characterized by  the tingling, numbness and the pain along the path of the a sciatic nerve in the affected leg . 

Basically like sciatica symptoms the causative factors include an abnormal tenseness or spasticity of the piriformis caused either by trauma and overuse or by muscle and nerve anatomical anomalies.

Anatomy of Piriformis Muscle

Let's revise some of the anatomy of the piriformis muscle . It is a small muscle which originates from the sacrum , the sciatic notch and the Sacro tuberous ligament.  And then runs through the greater sciatic foramen to attach to the greater trochant of the FEMA.  

Main action of Piriformis:

The main action of the piriformis is to externally rotate the hip,  so external rotation when the hip is in a flexed position . It also acts as a partial hip abductor the sciatic nerve runs just adjacent to the piriformis muscle.  Hence whenever the piriformis muscle is irritated or is inflamed it also affects the  a sciatic nerve which then results into the  sciatica like pain.

Past Cases of Sciatica:

In the past many cases of sciatica were attributed to the piriformis syndrome . However most if not all cases of sciatica are due to lumbosacral radiculopathy such as a disc protrusion at the lumbosacral spine or osteoarthritis at the lower lumbosacral area . 

Causes

So the causes of piriformis syndrome  are a number,  for example abnormal tenseness or spasticity of the piriformis muscle can be either caused by trauma or overuse injuries . 

Post-traumatic Piriformis Syndrome:

Post-traumatic piriformis syndrome may be secondary to a contusion to the gluteal area the bum which normally occurs in middle age. Recreational athletes playing tennis , running , cross-country,  skiing,  for example . 

Another cause is hypertrophy of the piriformis muscle which could compress the sciatic nerve and hypertrophy of the piriformis muscle can occur in athletes.  

Bipartite Piriformis Muscle Tumor:

Anatomical anomaly of the muscle and the nerve can also cause piriformis syndrome and about six percent of the population supposedly the sciatic nerve passes right through the piriformis muscle and then there's something called bipartite piriformis muscle and then this is really what's called bipartite piriformis muscle tumors , invading directly to the piriformis can then obstruct the sciatic nerve .

Vascular Anomalies:

And then you have vascular anomalies such as gluteal artery aneurysms which can also cause features of piriformis syndrome.  The clinical features of piriformis syndrome is really pain located maximally at the middle upper part of the bum.  

During and after physical exercise pain can radiate to the posterior thigh calf outer leg ankle and heel , basically sciatica type pain.  

There may be also pain at night in terms of posture the leg on the affected side may be held in semi-flexion and in external rotation to alleviate the pain . 

Differential Diagnosis:

There are a few differential diagnosis to consider firstly entrapment of the gluteal nerves can cause similar pain entrapment of posterior cutaneous . Nevertheless thigh can also cause hamstring pain and then you've got to think about the other causes of sciatica . 

Sciatica as Common term:

So remember that sciatica is a common term for a number of back and leg symptoms associated with the sciatic nerve and again the most common cause of sciatica is actually a disc prolapse or rupture and osteoarthritis within the lumbosacral spine. 

Clinical Examination

Straight Leg Raise Test:

So clinical examination though there is pinpoint tenderness on palpation of the upper middle gluteus when performing what's called a straight leg raise test .  This would be negative in piriformis syndrome but is positive in patients with sciatica from a lumbar cycle pathology.

However this is not very sensitive as it can also be technically positive in patients with piriformis syndrome . 

Log Roll Test:

There can be pain with the log roll test and this is internal and external rotation of the hip joint . The fair maneuver or the flexion adduction internal rotation maneuver would be positive so with the patient lying .

The Examiner passively flexes adducts and internally rotates the hip,  stretching the piriformis muscle which can then aggravate the pain reflexes motor function and sensation are usually normal . 

 Local Anesthetic Infiltration Test:

There's another test called the local anesthetic infiltration test . So basically when you put local anesthetic in the piriformis region if the pain disappears the test is positive investigations to order an MRI scan can be ordered and can demonstrate the size and thickness of the piriformis muscle the differences between the left and the right side and any anomalies.

So any anatomical differences an electroneuromyography examination May demonstrate distal radiculopathy or changes of proximal but not lumbar nerve root pathology which can help differentiate between lumbosacral pathology to piriformis syndrome.

Treatments

Conservative Management:

Finally treatment includes conservative management really you know stretching the muscle , pelvic posture correction,  core stabilization , hip and sacroiliac joint mobilization , strengthening of the gluteal and pelvic musculature , local anesthetic and a steroid injection into the piriformis muscle can be useful if physiotherapy fails and it's important not to actually inject directly onto the sciatic nerve .

Surgical Management:

Then there's surgical management and it's often offered after failure of the conservative management I mentioned earlier piriformis muscle is catagorize and the sciatic nerve can be released during  a surgery  and the results are good in majority of cases .

Conclusion

So in summary the piriformis syndrome is caused by irritation or compression of the sciatic nerve at the piriformis muscle the syndrome is characterized by tingling numbness and pain along the path of the sciatic nerve in the affected leg really similar symptoms to sciatica thank you for reading.