Answer for BIR CoW 21 Nov 2021
Complete left Persistant sciatic artery
Findings
Left leg demonstrated the presence of a large abnormal artery originating from an hypertrophic internal iliac artery that ran along the gluteal region and the posterior thigh and to the popliteal artery. There is an aneurysm in the gluteal segment of the anomolous artery which is thrombosed with evidence of distal shower of thrombus causing thrombosis of the major supply to the limb upto popliteal artery. The external iliac, the deep femoral, and the superficial femoral arteries showed a slightly reduced caliber but with no obstruction.
Discussion
Embryology: The sciatic artery is a continuation of the internal iliac artery and is the primary blood supply to the lower limb bud during early fetal development. During the 10-mm stage, the femoral artery begins to develop as a continuation of the external iliac artery. By 12 mm, the femoral and deep femoral arteries are present. By the 22-mm embryologic stage, the sciatic artery has atrophied at its midpoint in the distal thigh.Its proximal portion becomes the inferior and superior gluteal arteries, and the distal sciatic artery develops into the peroneal and popliteal arteries. The femoral artery continues to develop and establishes continuity with the popliteal artery, becoming the primary arterial supply of the distal lower limb.Simultaneously, the umbilical artery develops into the internal iliac artery. Several authors have suggested that the sciatic artery persists when the femoral arterial system is hypoplastic to deliver adequate blood flow to the developing limb. The sciatic artery normally involutes during fetal development, but remnants persist as the popliteal and peroneal arteries after the superficial femoral artery develops and establishes continuity with the popliteal artery.
A pathognomonic clinical sign for a PSA is the “Cowie’s sign” represented by a diminished or absent femoral pulse in combination with a palpable popliteal pulse.
Types: Type on the basis of the relationship between sciatic artery and femoral artery :
Complete- the most common appearance, the persistent sciatic artery runs to the popliteal artery representing the dominant supply for the lower limb while the superficial femoral artery is hypoplastic and provides only collateral vessels to the lower limb.
Incomplete -the persistent sciatic artery is hypoplastic and the superficial femoral artery is the main blood supply for the lower limb.
Complication: Development of aneurysm represents the most common complication(14–38% of incidence) , due to early atherosclerotic degeneration and often located at the level of the great trochanter in the gluteal region.
Etiology - hypoplasia of the elastic components may be an important factor of this wall degeneration . The persistent sciatic artery is also frequently aneurysmal, which may cause critical limb ischemia resulting from thrombosis or embolization of aneurysm thrombus. Failure to appreciate the persistent sciatic artery as the major inflow into the lower extremity may lead to inappropriate bypass of apparent occlusive disease of the superficial femoral artery.
References:
Ochsner J. 2017 Summer; 17(2): 189–194 J Vasc Surg. 1993 Aug;18(2):242-8
Findings
Left leg demonstrated the presence of a large abnormal artery originating from an hypertrophic internal iliac artery that ran along the gluteal region and the posterior thigh and to the popliteal artery. There is an aneurysm in the gluteal segment of the anomolous artery which is thrombosed with evidence of distal shower of thrombus causing thrombosis of the major supply to the limb upto popliteal artery. The external iliac, the deep femoral, and the superficial femoral arteries showed a slightly reduced caliber but with no obstruction.
Discussion
Embryology: The sciatic artery is a continuation of the internal iliac artery and is the primary blood supply to the lower limb bud during early fetal development. During the 10-mm stage, the femoral artery begins to develop as a continuation of the external iliac artery. By 12 mm, the femoral and deep femoral arteries are present. By the 22-mm embryologic stage, the sciatic artery has atrophied at its midpoint in the distal thigh.Its proximal portion becomes the inferior and superior gluteal arteries, and the distal sciatic artery develops into the peroneal and popliteal arteries. The femoral artery continues to develop and establishes continuity with the popliteal artery, becoming the primary arterial supply of the distal lower limb.Simultaneously, the umbilical artery develops into the internal iliac artery. Several authors have suggested that the sciatic artery persists when the femoral arterial system is hypoplastic to deliver adequate blood flow to the developing limb. The sciatic artery normally involutes during fetal development, but remnants persist as the popliteal and peroneal arteries after the superficial femoral artery develops and establishes continuity with the popliteal artery.
A pathognomonic clinical sign for a PSA is the “Cowie’s sign” represented by a diminished or absent femoral pulse in combination with a palpable popliteal pulse.
Types: Type on the basis of the relationship between sciatic artery and femoral artery :
Complete- the most common appearance, the persistent sciatic artery runs to the popliteal artery representing the dominant supply for the lower limb while the superficial femoral artery is hypoplastic and provides only collateral vessels to the lower limb.
Incomplete -the persistent sciatic artery is hypoplastic and the superficial femoral artery is the main blood supply for the lower limb.
Complication: Development of aneurysm represents the most common complication(14–38% of incidence) , due to early atherosclerotic degeneration and often located at the level of the great trochanter in the gluteal region.
Etiology - hypoplasia of the elastic components may be an important factor of this wall degeneration . The persistent sciatic artery is also frequently aneurysmal, which may cause critical limb ischemia resulting from thrombosis or embolization of aneurysm thrombus. Failure to appreciate the persistent sciatic artery as the major inflow into the lower extremity may lead to inappropriate bypass of apparent occlusive disease of the superficial femoral artery.
References:
Ochsner J. 2017 Summer; 17(2): 189–194 J Vasc Surg. 1993 Aug;18(2):242-8
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!