Introduction: After the term carotid siphon was introduced by Egas Moniz in 1927 to describe the radiographic appearance of the intracranial internal carotid artery (ICA), the term gained popularity during the following decades in both the anatomical and medical literature. With conflicting definitions persisting in the delineation of its proximal and distal sites, the authors explore if the term carotid siphon provides the precision needed for current anatomical and clinical studies?”
Methods: In the authors’ PubMed search of the term carotid siphon, more than 400 articles were identified from the anatomical and medical literature during the past six decades. They reviewed Moniz’s text and figures in his original Lancet article, and a compilation of other seminal historical articles and references to identify existing definitions of the term.
Results: Describing the radiographic silhouette of the normal ICA, Moniz defined the carotid siphon as the series of bends and curves; an additional curvature was identified called the double siphon. Throughout Moniz’s body of work, in text and figures, the boundaries of the carotid siphon were never delineated. Authors who followed attempted to correlate his original description of this two-dimensional radiographic projection with anatomical documentation.
Conclusions: Tracing the etymology of this word’s origin and usage during six decades in the medical literature shows continued discrepancy rather than consensus. We propose that the term is historically relevant but can now be supplanted by definitive ICA classification systems, which continue to evolve in contemporary medical and anatomical communications.
Patient Care: Our research highlights the confusion regarding the true definition of the carotid siphon and suggests the use of anatomically correlated ICA segmentation systems to improve medical communication.
Learning Objectives: By conclusion of the session, the participant should be able to 1) understand the origination of the carotid siphon by Egas Moniz including his writings and images, 2) understand its evolution in time from an angiographic sign to an anatomic term. 3) understand multiple historical conflicting definitions of the carotid siphon, and 4) understand the difficulty this creates in medical communication.
References: 1. Medline search. “Carotid Siphon.” www.pubmed.com. October 2012
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