In fibromuscular dysplasia, aneurysms are proximal to the area of thickening.

In fibromuscular dysplasia, aneurysms are proximal to the area of thickening.

• A. Distal
• B. Proximal
• C. Within the thickened area
• D. Both proximal and distal

Answer: (B)

In fibromuscular dysplasia, the beaded appearance on imaging comes from alternating areas of thickened (stenotic) segments and dilated, aneurysmal segments along the artery. The aneurysms tend to occur upstream, or proximal, to the thickened area. This happens because the segment just before a focal narrowing is exposed to higher pressure and altered flow, promoting dilation of the arterial wall there. The distal side beyond the stenosis is less prone to forming aneurysms in this pattern. So the aneurysm location being proximal to the thickened segment fits the characteristic beading of FMD.

In fibromuscular dysplasia, the beaded appearance on imaging comes from alternating areas of thickened (stenotic) segments and dilated, aneurysmal segments along the artery. The aneurysms tend to occur upstream, or proximal, to the thickened area. This happens because the segment just before a focal narrowing is exposed to higher pressure and altered flow, promoting dilation of the arterial wall there. The distal side beyond the stenosis is less prone to forming aneurysms in this pattern. So the aneurysm location being proximal to the thickened segment fits the characteristic beading of FMD.