Thursday, March 1, 2018

Persistent Sciatic Artery

Axial and coronal CT images with intravenous contrast demonstrate a left persistent sciatic artery (long arrows) coursing through the greater sciatic notch and deep to the gluteus maximus muscle. Note the asymmetrically diminutive left external iliac artery (short arrows)

  • A persistent sciatic artery (PSA) is a rare vascular anomaly in which the internal iliac artery courses through the greater sciatic notch and in to the thigh
    • During embryonic development, the sciatic artery usually involutes as the femoral artery develops
    • Recognition of an unusually enlarged internal iliac artery and a diminutive external iliac artery are some clues in diagnosing a PSA
    • The PSA course runs close to the sciatic nerve, and can run within the nerve sheath in some cases
    • Distally, the PSA runs deep to the gluteus maximus muscle, coursing along the adductor magnus muscle
  • Reported in up to 0.03-0.06% of the population and can be bilateral in 20% of cases
  • PSA is considered complete when it is the dominant blood supply to the popliteal artery and incomplete with the femoral artery is the dominant blood supply to the popliteal artery
  • 5 types have been described:
    • type 1 is a complete PSA with a normal femoral artery
    • type 2 is a complete PSA with a incompletely developed femoral artery
    • type 3 is a incomplete PSA (only the cephalic portion is present) and normal femoral artery
    • type 4 is a incomplete PSA (only the caudal portion is present) and normal femoral artery
    • type 5 is when the PSA arises from the median sacral artery
  • Majority (80%) become symptomatic at some point presenting with intermittent claudication, ischemia, pulsatile mass or neurologic symptoms
  • Susceptible to repetitive trauma from sitting and hip flexion/extension
    • Results in premature atherosclerosis and aneurysm formation
    • Aneurysm found in 48%, and stenosis and occlusion of the PSA in 7% and 9%, respectively
References:
  1. Mcquaid M, Gavant ML. Posttraumatic pseudoaneurysm of a persistent sciatic artery. AJR Am J Roentgenol. 1995;164 (6): 1514-5. 
  2. Pillet J, Albaret P, Toulemonde JL, Cronier P, Raimbeau G, Chevalier JM. Tronc arteriel ischiopoplite, persistance de l’artere axiale. Bull Assoc Anat 1980;64:109e22.
  3. Pillet J, Cronier P, Mercier Ph, Chevalier JM. The ischio popliteal arterial trunk: a report of two cases. Anat Clin 1982; 3:329e31. 
  4. Gauffre S, Lasjaunias P, Zerah M. Sciatic artery: a case, review of literature and attempt of systematization. Surg Radiol Anat 1994;16(1):105e9.
  5. Bower EB, Smullens SN, Parke WW. Clinical aspect of persis- tent sciatic artery: report of two cases and review of the literature. Surgery 1977;81(5):588e95.

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