Abstract
Stating background
The piriformis syndrome is one of the non-discogenics causes of sciatica. It results from the compression of the sciatic nerve (SN) by the piriformis muscle (PM) in the neutral and piriformis stretch test position. The evidence of the increase in pain in the test position requires a detailed anatomical study addressing the changes that occurred in the SN and PM anatomy during the test position. The aim of this study is to examine this relationship morphometrically.
Materials and methods
A total of 20 right and left lower limbs of ten adult cadavers were examined. The SN and the PM were made visible. The location of the SN was evaluated with respect to the consistent bony landmarks, including the greater and the lesser trochanter of the femur, the ischial tuberosity, the ischial spine of the hip bone, the posterior inferior iliac spine of the hip bone and the posterior superior iliac spine of the hip bone. The study was done in both neutral and test positions (i.e., 30° adduction 60° flexion and approximately 10° medial rotation position of the hip joint).
Results
The width of the greater sciatic notch was 63.09 ± 13.59 mm. The length of the lower edge of the PM was 95.49 ± 6.21 mm, and whereas the diameter of the SN where it emerged from the infrapiriforme was 17.00 ± 3.70 mm, the diameter decreased to 11.03 ± 2.52 mm at the level of the lesser trochanter of the femur. The SN intersected the PM most commonly in its medial second quarter anatomically. The vertical distance between the medial edge of the SN–PM intersection point and the ischial tuberosity was 85.62 ± 17.23 and 72.28 ± 7.56 mm (P < 0.05); the angle between the SN and the transverse plane was 66.36° ± 6.68° and 71.90 ± 8.48° (P < 0.05); and the vertical distance between the medial edge of the SN and the apex of the ischial spine of the hip bone was 17.33 ± 4.89 and 15.84 ± 4.63 mm (P > 0.05), before and after the test position, respectively.
Conclusion
This study provides helpful information regarding the course and the location of the SN. The presented morphometric data also revealed that after stretch test position, the infrapiriforme foramen becomes narrower; the SN becomes closer to the ischial spine of the hip bone, and the angle between the SN and the transverse plane increases. This study confirmed that the SN is prone to be trapped in the test position, and diagnosis of this situation requires dynamic MR and MR neurography study.
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References
Arifoğlu Y, Sargon MF, Tanyeli E, Yazar F (1997) Double superior gemellus together with double piriformis and high division of the sciatic nerve. Surg Radiol Anat 19:407–408
Babinski MA, Machado FA, Costa WS (2003) A rare variation in the high division of the sciatic nerve surrounding the superior gemellus muscle. Eur J Morphol 41(1):41–42
Barton PM (1991) Piriformis syndrome: a rational approach to management. Pain 47:345–352
Beaton LE, Anson BJ (1937) The relation of the sciatic nerve and of its subdivisions to the piriformis muscle. Anat Rec 70(supp1):1–5
Beaton LE, Anson BJ (1938) The sciatic nerve and the piriformis muscle: their interrelation a possible cause of coccygodynia. J Bone Joint Surg 20:686–688
Benzon HT, Katz JA, Benzon HA, Iqbal MS (2003) Anatomic considerations, a new injection tecnique and a review of the literature. Anesthesiology 98:1442–1448
Broadhurst NA, Simmons N, Bond MJ (2004) Piriformis syndrome: correlation of muscle morphology with symptoms and signs. Arch Phys Med Rehabil 85:2036–2039
Chen WS (1994) Bipartite piriformis muscle: an unusual cause of sciatic nerve entrapment. Pain 58:269–272
Filler AG, Haynes J, Jordan SE, Prager J, Villablanca P, Farahani K, Mcbride DQ, Tsuruda JS, Morisoli B, Batzdorf U, Johnson JP (2005) Sciatica of nondisc origin and piriformis syndrome: diagnosis by magnetic resonance imaging with outcome study of resulting treatment. J Neurosurg Spine 2:99–115
Foster MR (2002) Piriformis syndrome. Orthopedics 25(8):821–825
Jankiewicz JJ, Hennrikus WL, Houkom JA (1991) The apperance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging. Clin Orthop Relat Res 262:205–209
Kendall FP, Kendall McCreart E, Geise PP (1993) Muscles testing and function, 4th edn. Williams & Wilkins, Baltimore, pp 219, 333, 365
Kırıcı Y, Ozan H (1999) Double gluteus maximus muscle with associated variations in the gluteal region. Surg Radiol Anat 21(6):397–400
Kırıcı Y, Yazar F, Ozan H (1999) The neurovascular and muscular anomalies of the gluteal region: an atypical pudendal nerve. Surg Radiol Anat 21(6):393–396
Kosukegawa I, Yoshimoto M, Isogai S, Nonaka S, Yamashita T (2006) Piriformis syndrome resulting from a rare anatomic variation. Spine 31(18):E 664–6
Mas N, Özekşi P, Özdemir B, Kapakin S, Sargon MF, Çelik HH, Yener N (2003) A case of bilateral high division of the sciatic nerves, together with a unilateral unusual course of the tibial nerve. Neuroanatomy 2:13–15
Ozaki S, Hamabe T, Muro T (1999) Piriformis syndrome resulting from an anomalous relationship between the sciatic nerve and piriformis muscle. Orthopedics 22(8):771–772
Papadopoulos EC, Khan SN (2004) Piriformis syndrome and low back pain: a new classification and review of the literature. Orthop Clin Am 35:65–71
Parziale JR, Hudgins TH, Fishman LM (1996) The piriformis syndrome. Am J Orthoped 25(12):819–823
Patriquin ML, Steyn M, Loth SR (2005) Metric analysis of sex differences in South African black and white pelvis. Forensic Sci Int 147:119–127
Pecina M (1979) Contribution to the explanation of the piriformis syndrome. Acta Anat 105:181–187
Pokorny D, Jahoda D, Veigl D, Pinskerova V, Sonsa A (2006) Topographic variations of the relationship of the sciatic nerve and the piriformis muscle and its relevance to palsy after total hip arthroplasty. Surg Radiol Anat 28(1):88–91
Porta M (2000) A comparative trial of botulinum toxin type A and methylprednysolone for the treatment of myofacial pain from chronic muscle spasm. Pain 85:101–105
Sayson SC, Ducey JP, Maybrey JB, Wesley RL, Vermilion D (1994) Sciatic entrapment neuropathy associated with an anomalous piriformis muscle. Pain 59:149–152
Standring S (editor-in-chief) (2005) Gray’s anatomy The anatomical basis of clinical practice, 39th edn. Elsevier, Amsterdam, pp 1403, 1404, 1446, 1447
Uchio Y, Nishikawa U, Ochi M, Shu N, Takata K (1998) Bilateral piriformis syndrome after total hip arthroplasty. Arch Orthop Trauma Surg 117:177–179
Uluutku MH, Kurtoğlu Z (1999) Variations of nerves located in deep gluteal region. Okajimas Folia Anat Jpn 76(5):273–276
Vallejo MC, Mariano DJ, Kaul B, Sah N, Ramanathan S (2004) Piriformis syndrome in a patient after cesarean section under spinal anesthesia. Reg Anesth Pain Med 29(4):364–367
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Güvençer, M., Akyer, P., İyem, C. et al. Anatomic considerations and the relationship between the piriformis muscle and the sciatic nerve. Surg Radiol Anat 30, 467–474 (2008). https://doi.org/10.1007/s00276-008-0350-5
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DOI: https://doi.org/10.1007/s00276-008-0350-5