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The patient with an unrelenting sciatica may be suffering with a piriformis syndrome. This syndrome is considered an entrapment neuropathy caused by pressure on the sciatic nerve by an enlarged or inflamed piriformis muscle. The sciatic nerve can be compressed between the swollen muscle fibers and the bony pelvis.1 Besides backache, the piriformis muscle contracture and associated adhesions has been related to radiating pain from the sacrum to the hip joint over the gluteal region to the posterior thigh, coccydynia,4 dyspareunia, male impotency5, and oblique axis rotation of the sacrum with its effect on the total spine up to the atlanto-occipital region.5
According to Gray6 and Freiberg7 the piriformis arises from the anterior sacrum between the second to fourth anterior sacral foramina, from the margin of the greater sciatic foramen and from the anterior surface of the sacrotuberous ligament, the anterior sacrospinous ligament and the capsule of the sacroiliac joint. Freiberg states that the piriformis is the only muscle that bridges the sacroiliac joint. The piriformis passes through the greater sciatic foramen (the upper part of which it fills) and inserts by a rounded tendon into the upper border of the greater trochanter.
Pecian8 examined 130 human specimens to determine the anatomical relations of the sciatic nerve and the piriformis. He found that in 6.15 percent of the cases the peroneal part of the sciatic nerve passes between the tendinous parts of the piriformis and a pinching of the nerve can occur. He found at least five other variations of the sciatic nerve in relation to the piriformis muscle. He concluded that when the nerve passed between the tendinous portion of the piriformis the nerve would more likely be pinched during passive medial rotation of the thigh which stretches the piriformis, causing the nerve to be pressed against the extended piriformis. In this case, resisted testing of the piriformis or ordinary active piriformis contraction would separate the tendinous portion of the piriformis surrounding the sciatic nerve and would not compress the nerve.
Mizuguche9 felt that before the piriformis could aggravate the sciatic nerve there first had to be a preexisting tension on the sciatic nerve by scarring or arachnoiditis around the nerve roots secondary to laminectomy or some space-occupying lesion such as osteoarthritic spurs. He thought that ordinary walking would cause the piriformis to impinge the shortened nerve. A history of trauma to the sacroiliac or gluteal region has also been blamed10.
Warren Hammer, M.S., D.C., D.A.B.C.O.
References
1. Jankiewicz JJ, Hennrikus WL, Houkom JA: "The appearance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging: a case report and review of the literature." Clin Orth & Rel Res:262,205-209.
4. Thiele GH: "Tonic spasm of the levator ani, coccygeus and piriformis muscles." Trans Am Pract Soc 37:145-155, 1936.
5. Retzlaff E, Berry AH, Haight AS et al. "The piriformis muscle syndrome." J AM Osteopath Assoc 73:799-807.
6. Gray H: Anatomy of the Human Body. 26th ed. Philadelphia: Lea & Febiger, 1956:541.
7. Freiberg AH: "Sciatic pain and its relief by operations on the muscle and fascia." Arch Surg 34:337m 1937.
8. Pecian M: "Contribution to the etiological explanation of the piriformis syndrome." Acta Anat (Basel) 105:181-186, 1979.
9. Mizughuchi T: "Division of the piriformis muscle in the treatment of sciatica." Arch Surg 111:719-722, 1976.
10. Robinson D: "Piriformis syndrome in relation to sciatic pain." Am J Surg 73:356-358, 1947.
11. Freiburg AH, Vinke TA: "Sciatica and the sacroiliac join." J Bone Joint Surg 16:126, 1934.
The patient with an unrelenting sciatica may be suffering with a piriformis syndrome. This syndrome is considered an entrapment neuropathy caused by pressure on the sciatic nerve by an enlarged or inflamed piriformis muscle. The sciatic nerve can be compressed between the swollen muscle fibers and the bony pelvis.1 Besides backache, the piriformis muscle contracture and associated adhesions has been related to radiating pain from the sacrum to the hip joint over the gluteal region to the posterior thigh, coccydynia,4 dyspareunia, male impotency5, and oblique axis rotation of the sacrum with its effect on the total spine up to the atlanto-occipital region.5
According to Gray6 and Freiberg7 the piriformis arises from the anterior sacrum between the second to fourth anterior sacral foramina, from the margin of the greater sciatic foramen and from the anterior surface of the sacrotuberous ligament, the anterior sacrospinous ligament and the capsule of the sacroiliac joint. Freiberg states that the piriformis is the only muscle that bridges the sacroiliac joint. The piriformis passes through the greater sciatic foramen (the upper part of which it fills) and inserts by a rounded tendon into the upper border of the greater trochanter.
Pecian8 examined 130 human specimens to determine the anatomical relations of the sciatic nerve and the piriformis. He found that in 6.15 percent of the cases the peroneal part of the sciatic nerve passes between the tendinous parts of the piriformis and a pinching of the nerve can occur. He found at least five other variations of the sciatic nerve in relation to the piriformis muscle. He concluded that when the nerve passed between the tendinous portion of the piriformis the nerve would more likely be pinched during passive medial rotation of the thigh which stretches the piriformis, causing the nerve to be pressed against the extended piriformis. In this case, resisted testing of the piriformis or ordinary active piriformis contraction would separate the tendinous portion of the piriformis surrounding the sciatic nerve and would not compress the nerve.
Mizuguche9 felt that before the piriformis could aggravate the sciatic nerve there first had to be a preexisting tension on the sciatic nerve by scarring or arachnoiditis around the nerve roots secondary to laminectomy or some space-occupying lesion such as osteoarthritic spurs. He thought that ordinary walking would cause the piriformis to impinge the shortened nerve. A history of trauma to the sacroiliac or gluteal region has also been blamed10.
Warren Hammer, M.S., D.C., D.A.B.C.O.
References
1. Jankiewicz JJ, Hennrikus WL, Houkom JA: "The appearance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging: a case report and review of the literature." Clin Orth & Rel Res:262,205-209.
4. Thiele GH: "Tonic spasm of the levator ani, coccygeus and piriformis muscles." Trans Am Pract Soc 37:145-155, 1936.
5. Retzlaff E, Berry AH, Haight AS et al. "The piriformis muscle syndrome." J AM Osteopath Assoc 73:799-807.
6. Gray H: Anatomy of the Human Body. 26th ed. Philadelphia: Lea & Febiger, 1956:541.
7. Freiberg AH: "Sciatic pain and its relief by operations on the muscle and fascia." Arch Surg 34:337m 1937.
8. Pecian M: "Contribution to the etiological explanation of the piriformis syndrome." Acta Anat (Basel) 105:181-186, 1979.
9. Mizughuchi T: "Division of the piriformis muscle in the treatment of sciatica." Arch Surg 111:719-722, 1976.
10. Robinson D: "Piriformis syndrome in relation to sciatic pain." Am J Surg 73:356-358, 1947.
11. Freiburg AH, Vinke TA: "Sciatica and the sacroiliac join." J Bone Joint Surg 16:126, 1934.
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