Piriformis syndrome, aka deep gluteal syndrome (35), was first described in 1928 and arises when a hypertonic or irritated piriformis muscle compresses the proximal sciatic nerve. (1) This pressure causes neurologic ischemia, congestion, local inflammation, and radiating complaints. (2) Researchers estimate that piriformis syndrome contributes to up to one-third of all back-related pain. (3,4)
The piriformis muscle originates on the anterolateral surface of the mid-portion of the sacrum and inserts on the superior medial aspect of the greater trochanter. When the hip is extended, the piriformis functions primarily as an external rotator of the thigh, with secondary contributions toward flexion. The muscle assists in abduction when the hip is flexed to 90 degrees. (3) The emergence of the sciatic nerve and its relationship to the piriformis muscle is quite variable. (50,51) In the majority of the population, the sciatic nerve travels deep to the muscle. (51) Up to one-fourth of the population is anatomically predisposed to piriformis syndrome because their sciatic nerve passes through the muscle, splits the muscle, or both. (5,6,37) The innervation to the piriformis is somewhat variable, but typically consists of 2-3 branches; most commonly the superior gluteal nerve (70%), and the ventral rami of S1 (85%) and S2 (70%). (32)
In addition to compression by the piriformis, the sciatic nerve is vulnerable to entrapment by a congenitally narrowed ischio-femoral space, vascular abnormalities, space-occupying lesions, myositis ossificans, fibrous bands, and various other adjacent muscles including, the hamstring, gluteal muscles, and the gemelli-obturator internus complex. (41-50) Hence, the more encompassing descriptor deep gluteal syndrome may be appropriate for some cases.
Of note, the sciatic nerve supplies sensation to the lower leg and foot but provides no direct cutaneous innervation to the buttock or posterior thigh. Piriformis related symptoms affecting the posterior thigh are thought to arise from compression of the inferior gluteal vein (by the piriformis), causing ischemia to the posterior femoral cutaneous nerve- the independent branch of the sciatic nerve that innervates the posterior thigh. (39,52)
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What we do in our office to help this condition:
1. Perform a detailed exam, assessing the alignment of the spine, pelvis, hips, knees, ankles, and small bones of the foot. Improper alignment in any of these areas may be detrimentally affecting the function of the piriformis muscle, and compromising its ability to function normally.
2. As indicated, adjust areas of spinal and extremity subluxations (misalignments), restoring proper nerve system function which facilitates healing.
3. Perform laser therapy which penetrates to the cellular level of the soft tissues surrounding the piriformis. This promotes better oxygen and nutrients to the tissue, which can relieve pain and facilitate the healing process.
4. Prescribe stretches and exercises in conjunction with chiropractic care to strengthen the piriformis and surrounding soft tissues.