Flow Conditions in the Intracranial Aneurysm Lumen Are Associated with Inflammation and Degenerative Changes of the Aneurysm Wall.
Saccular intracranial aneurysm is a common disease that may cause devastating intracranial hemorrhage. Hemodynamics, wall remodeling, and wall inflammation have been associated with saccular intracranial aneurysm rupture. We investigated how saccular intracranial aneurysm hemodynamics is associated with wall remodeling and inflammation of the saccular intracranial aneurysm wall.



Tissue samples resected during a saccular intracranial aneurysm operation (11 unruptured, 9 ruptured) were studied with histology and immunohistochemistry. Patient-specific computational models of hemodynamics were created from preoperative CT angiographies.



More stable and less complex flows were associated with thick, hyperplastic saccular intracranial aneurysm walls, while slower flows with more diffuse inflow were associated with degenerated and decellularized saccular intracranial aneurysm walls. Wall degeneration (P = .041) and rupture were associated with increased inflammation (CD45+, P = .031). High wall shear stress (P = .018), higher vorticity (P = .046), higher viscous dissipation (P = .046), and high shear rate (P = .046) were associated with increased inflammation. Inflammation was also associated with lack of an intact endothelium (P = .034) and the presence of organized luminal thrombosis (P = .018), though overall organized thrombosis was associated with low minimum wall shear stress (P = .034) and not with the flow conditions associated with inflammation.



Flow conditions in the saccular intracranial aneurysm are associated with wall remodeling. Inflammation, which is associated with degenerative wall remodeling and rupture, is related to high flow activity, including elevated wall shear stress. Endothelial injury may be a mechanism by which flow induces inflammation in the saccular intracranial aneurysm wall. Hemodynamic simulations might prove useful in identifying saccular intracranial aneurysms at risk of developing inflammation, a potential biomarker for rupture.
From the Bioengineering Department (J.C., B.J.C., F.M.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia.
J
0000-0002-3216-0856
J
Cebral
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
E
0000-0001-5470-4474
E
Ollikainen
From the Bioengineering Department (J.C., B.J.C., F.M.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia.
B J
0000-0002-5846-7944
BJ
Chung
From the Bioengineering Department (J.C., B.J.C., F.M.), Volgenau School of Engineering, George Mason University, Fairfax, Virginia.
F
0000-0003-1907-3739
F
Mut
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
V
0000-0002-8393-6415
V
Sippola
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
B R
0000-0003-3937-2816
BR
Jahromi
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland.|Department of Vascular Surgery (R.T.), Helsinki University Central Hospital, Helsinki, Finland.
R
0000-0003-1103-0216
R
Tulamo
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
J
0000-0001-8163-8804
J
Hernesniemi
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland.
M
0000-0003-1526-0684
M
Niemelä
Mechanical Engineering and Materials Science and Department of Bioengineering (A.R.), Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania.
A
0000-0002-5063-4293
A
Robertson
Neurosurgery Research Group (E.O., V.S., B.R.J., R.T., J.H., M.N., J.F.), Biomedicum Helsinki and Helsinki University Central Hospital, Helsinki, Finland juhana.frosen@kuh.fi.|Department of Neurosurgery and Hemorrhagic Brain Pathology Research Group (J.F.), Neurocenter, Kuopio University Hospital, Kuopio, Finland.
J
0000-0003-4677-950X
J
Frösen
D017542:Aneurysm, Ruptured / Q000473:pathology / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000473:pathology / Q000503:physiopathology*; D002532:Intracranial Aneurysm / Q000473:pathology / Q000503:physiopathology*; D013314:Stress, Mechanical; D066253:Vascular Remodeling / Q000502:physiology*
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