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.