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Letter Regarding: Dolichoectasia of the internal carotid artery terminus, posterior communicating artery, and posterior cerebral artery: The embryonic caudal ramus internal carotid segmental vulnerability legacy

Dear Editor, We read with interest the article published by Kobkitsuksakul et al. titled “Dolichoectasia of the internal carotid artery terminus, posterior communicating artery, and posterior cerebral artery: The embryonic caudal ramus internal carotid segmental vulnerability legacy.” Our group has published a case series of patients with a similar angiographic finding as that shown in this article. Based on our review of the literature, we have proposed the name “Pure Arterial Malformation” to describe these lesions rather than dolichoectasia as we feel that dolichoectasia is more commonly recognized as a pathological process associated with advanced age and atherosclerotic risk factor. Pure arterial malformations on the other hand are likely congenital. In terms of definitions, we define pure arterial malformations as dilated, overlapping, and tortuous arteries forming a mass of arterial loops with a coillike appearance in the absence of any arteriovenous connection, as proposed by McLaughlin et al. All of the patients shown in Kobkitsuksakul et al.’s article had what we would define as the classic findings of a pure arterial malformation. In our series, we identified 12 patients who had pure arterial malformations, 10 females and 2 males. Mean age was 26.2 years old. Only one patient had imaging findings of a connective tissue disease (bicuspid aortic valve and thoracic aortic dilatation). In 10 of 12 patients, the finding was likely completely incidental, and in 2 of 12 cases, it was associated with transient thunderclap headache or transient ischemic attack. In no cases did any of these lesions rupture or present with cerebral infarction. Five lesions were partially calcified and one case was associated with a malformation of cortical development. We also identified an additional 20 reported cases of pure arterial malformations in the literature dating back to 1969. The pathogenesis and etiology of pure arterial malformations is somewhat unclear. Potential etiologies we have suggested include (1) a congenital defect or insult resulting in an arterial dysplasia (we have seen cases associated with cerebral lipomas or cortical dysplasias); (2) an insult such as a viral infection or somatic mutation occurring later in life and affecting a particularly vulnerable arterial segment (i.e., the segmental arterial vulnerability hypothesis of Lasjaunias); or (3) a chronic healed dissection. Ultimately, this angiographic appearance may be the common manifestation of each of these three pathologic processes as we have seen evidence of all three in our population of pure arterial malformation patients. Regarding management, we have elected to manage these patients conservatively. We have yet to see any lesion progress to become symptomatic or result in hemorrhage in our case series which now numbers 25 patients, although other authors have clearly documented aneurysmal progression in one patient overtime stressing the importance of clinical and radiological follow-up.