GENERAL
The Piriformis Muscle Syndrome is a disorder in which the piriformis muscle irritates the sciatic nerve and causes pain starting from the buttock, radiating posteriorly to the thigh and down to the foot. The pain is similar to the typical sciatica resulting from a herniated intervertebral disc. The syndrome is more frequent in women and in individuals who exercise systematically, e.g. runners.
The syndrome occurs when the muscle is dilated or in permanent contraction, exerting pressure on the sciatic nerve which courses right under the piriformis muscle. In piriformis muscle syndrome, the sciatic pain from irritation of sciatic nerve is of peripheral aetiology and is not induced by nerve root inflammation from herniated intervertebral disc or any other spinal disorder, as happens in typical sciatica. However, the symptoms are almost the same in both conditions and the patient sometimes is wrongly led to spinal surgery, for the pain still persists even after the surgery.
WHERE IS THE PIRIFORMIS MUSCLE LOCATED?
The piriformis muscle is a small muscle located deep in the buttock region below the gluteus maximus (major gluteal muscle).
It originates from the lower part of the spine and ends to the top side of femoral bones.
Its functional role is to assist in hip joint rotation.The sciatic nerve passes right under the piriformis muscle and courses vertically to its direction.
Piriformis Syndrome
DIAGNOSIS
The diagnosis is based on the detailed history and careful clinical examination of the patient. The most common symptoms reported by the patients are acute tenderness in the buttock region where the muscle is located, pain and numbness at the posterior aspect of the hip extending down to the heel and toes. The pain is aggravated with walking, exercising, going up stairs and prolonged sitting. Lying down and abstaining from sports activities improves the pain.
Due to the similarity of symptoms in piriformis muscle syndrome with typical sciatica, there is often a differential diagnostic dilemma in identifying the real cause of sciatic pain. The dilemma in question is the following: “Is the sciatic pain induced by the sciatic nerve irritation distally or is it caused by the nerve root inflammation resulting from spinal pathology?
The lumbar spine MRI is an imaging technique that can clarify the probable spinal pathology. However, it provides only morphological information. So, there are cases in which, the MRI may reveal a herniated L5-S1 or L4-L5, but still the real cause of the sciatic pain may actually be of a more peripheral origin. Besides, there are many patients who remain asymptomatic despite the fact that the MRI has revealed sizeable disc herniations.
Therefore, in case the MRI is clear, not showing any anatomic abnormalities, a treatment has to be planned, at least initially, to confront the piriformis muscle syndrome.
Should the MRI show anatomic abnormalities at the lower lumbar spine levels that could probably explain the sciatic pain, the dilemma is then resolved as follows:
Electromyogram (EMG) to confirm further the level of the lesion.
There are quite many cases in which patients underwent surgical discectomy because their treatment was based on MRI findings and, eventually, to everybody’s surprise and disappointment, their pain still remained exactly the same right after waking up from anaesthesia….
TREATMENT
Stretching exercises for the muscle group of gluteals and hamstrings- Abstaining from sports activities
- Physiotherapy
- Chiropractics
- Ice therapy
- Anti-inflammatory drugs
- Injection of corticosteroids and local anaesthetic into the piriformis muscle under radiological guidance
- Transcutaneous Electrical Nerve Stimulation (TENS)
MEDICAL INFORMATION SOURCES
1. PAIN PRACTICE JOURNAL
2. BONICA”S MANAGEMENT OF PAIN
3. PAIN PHYSICIAN JOURNAL
4. INTERVENTIONAL PAIN MANAGEMENT BOOK
