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. 2022 Apr 11;53(8):2458–2467. doi: 10.1161/STROKEAHA.121.037904

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© 2022 The Authors.

Stroke is published on behalf of the American Heart Association, Inc., by Wolters Kluwer Health, Inc. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial-NoDerivs License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited, the use is noncommercial, and no modifications or adaptations are made.

This article is made available via the PMC Open Access Subset for unrestricted re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the COVID-19 pandemic or until permissions are revoked in writing. Upon expiration of these permissions, PMC is granted a perpetual license to make this article available via PMC and Europe PMC, consistent with existing copyright protections.

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Figure 1. — Classification of extracranial and cavernous internal carotid artery (ICA) tortuosity. A, Tortuosity of the extracranial ICA was classified into 4 types as follows: straight (angle between the centerlines of the common carotid artery and the ICA was <15°), tortuous (angle between the common carotid artery and the ICA centerlines was >15; or S- or C-shaped course of the ICA), coiled (an exaggerated S-shaped curve or circular configuration of the ICA), and kinked (acute [<90°] angulation associated with stenosis).¹¹ The extracranial ICA was considered tortuous if it was coiled or kinked. B, Cavernous ICA tortuosity was classified into 4 types based on the geometry of the anterior and posterior genus. Type I has open configurations/angles of anterior and posterior genus (the posterior genu angle [P] ≥90°). Type II is characterized by a closed configuration of the anterior genu (more acute angle of the anterior genu [A] than type I). Type III is defined by posterior deflection of the posterior genu, which gives it a buckled appearance. Type IV is the most tortuous and has a shape characteristic of the Simmons-style angiography catheter where the posterior genu is buckled superiorly compared with the anterior genu.¹² H is the height difference of the anterior and posterior genus, measured from the peak of the posterior genu to the trough of the anterior genu. Types III and IV were considered tortuous cavernous ICA.