Aberrant extracranial internal carotid arteries: New insights, implications, and demand for a clinical grading system.

Background. Aberrant internal carotid arteries (ICAs) are not rare anatomic variations. The purpose of this study was for us to highlight their relevance and underline the need for a clinical grading system in addition to the currently used anatomic classification. Methods. This systematic quality assessment study over 7 years includes 125 adults with 231 aberrant ICAs. Digital imaging datasets were analyzed and ICAs classified according to the anatomic classification in tortuosity, kinking, and coiling. Risk potential for ICA injury was estimated from the vessel's relation to the pharynx and neck. Results. The analysis revealed a high frequency of medial and lateral ICA aberrations that seem surgically relevant, but the risk potential for injury was not reflected by the anatomic classification. Our previously proposed clinical grading system was reviewed and updated. Conclusion. Aberrant ICAs are underestimated anatomic variations with high clinical impact for transoral and transcervical interventions. The introduced clinicoradiologic grading system could be of major benefit. (C) 2015 Wiley Periodicals, Inc.