Objective:

This study aimed to develop and validate a quantitative vessel tortuosity scale to characterize cerebral vascular geometry and assess its relationship with aneurysm formation and rupture.

Background:

Nontraumatic subarachnoid hemorrhage is often due to a ruptured cerebral aneurysm (CA). Vessel tortuosity is associated with numerous vascular diseases. Recent data suggests that tortuosity may correlate with aneurysm formation and progression.

Design/Methods:

A well-established, elastase-mouse CA model was used to assess cerebral vessel tortuosity in correlation with CA formation/rupture in sham (n=13), 3.5mU (n=14), and 35 mU (n=20) elastase groups. Quantitative (tortuosity index) and qualitative (large and small vessel curvature) analysis were used to create an ordinal visual scale ranging from 1 (low tortuosity) to 4 (high tortuosity) to evaluate predictive capacity for vessel tortuosity level and CA formation and rupture.

Results:

Nearly all sham animals (92%) had little to no vessel tortuosity on the visual scale (median, IQR: 1, [1-2]), compared to 29% in the 3.5mU (2, [1.25-3]), and 21% in the 35mU (2, [2-3]) cohorts. Sham cohorts had zero animals with highly tortuous vessels while 3.5mU and 35mU cohorts had >35% of animals with significant visual tortuosity, p=0.003 and p<0.000, respectively. CA formation and rupture was significantly higher in the elastase groups compared to the sham group (p=0.002). Both the visual scale and tortuosity index significantly predicted CA formation (p<0.001) and rupture (p<0.000).

Conclusions:

A novel tortuosity scale is highly predictive of CA formation and rupture in vivo and may offer a novel measurement to better understand vessel stress in the natural history of CAs.