Which finding is inconsistent with total occlusion of the internal carotid artery?

Total occlusion of the internal carotid artery (ICA) presents specific findings on imaging studies, and understanding these findings is crucial for establishing a proper diagnosis.

The presence of retrograde flow in the distal ICA is inconsistent with total occlusion. If the ICA is completely occluded, there should be no forward flow detected past the point of obstruction. Instead, the flow dynamics would lead to no measurable flow within the distal segments of the ICA. Essentially, total occlusion implies that blood cannot pass through the artery from the proximal to the distal end, removing the possibility of retrograde flow occurring in that segment.

In contrast, other findings associated with total occlusion include an absence of flow in the ICA lumen, which confirms that the artery is occluded; decreased velocity proximal to the occlusion, which indicates diminished blood flow due to the absence of downstream support; and an increase in flow through collateral pathways, which often occurs as the body compensates for lost flow through the occluded artery by utilizing alternative routes for blood delivery. These findings are consistent with a complete blockage of the artery and highlight the body's adaptive mechanisms in response to vascular occlusions.