外頸動脈が内頸動脈に連続移行した内頸動脈起始部欠損症の1例

Agenesis of the Internal Caroud Artery with an Unusual Collateral Pathway

I．はじめに

　内頸動脈欠損症は，1787年Tode^10）により剖検例が最初に発表され，1929年Dandyにより血管造影を行った症例が初めて報告された．以来，多くの報告例がみられるようになり，その発生学，血管造影所見について詳しく論じられている．内頸動脈欠損症の脳動脈血行路は，さまざまな型をとりうるものであるが，今回われわれは文献上極めて稀な動脈血行路を持った内頸動脈欠損症の1例を経験したので，発生学的観点から考察を加え報告する．

A 65-year-old male developed severe headache of sudden onset 3 months prior to admission.

The right retrograde brachial angiogram revealed that the right internal carotid artery was absent. The extremely dilated external carotid artery on the right side continued to the extracranial portion of the right internal carotid artery. No other collateral pathways were found.

From an embryological point of view, it is specu-lated that the aortic arch III might have been mal-developed and the distal portion of the dorsal aorta might have received a collateral circulation via a persistent aortic arch I or II.