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 wish to thank the readers for their interest in our article and additional insightful comments, in particular, regarding the term used in this extraordinary intracranial vasculopathy. The term “Dolichoectasia” is commonly be described in the vertebrobasilar system, and it defines as elongation, distension, and tortuosity.^1,2 Our demonstrated cases are almost identical to the distinctive article published by Brinjikji et al.^2,3 The abnormal vessels in our series, embryological theory, are the descendant of the caudal ramus internal carotid artery.⁴ Their vascular architectures are beyond the definition of dolichoectasia. They are tight coils, bizarre, and almost unrecognizable vestige. The reader proposed the name “pure vascular malformation” instead of using “dolichoectasia,” which has drawn considerable interest in our opinion. However, the term malformation is mostly used in the arteriovenous shunt diseases; therefore, the malformation may intricate or mistaken the non-neurovascular people.

Also, several terms have been discussed among the anatomist and embryologist communities, for example, congenital arterial anomaly or dysgenesis which links to the embryological abluminal formation as the etiology.⁵ This explanation is included but not limited to the fenestrated or duplicate vessels. We see exactly what the readers mean, and consensus terminology among the neurovascular experts may lessen several different terms used in this particular abnormality.

Despite unclear pathogenesis and etiology, we agree with the readers that the disease tends toward congenital defect as we proposed that some factors likely affect the early stage of life, e.g., viral infection, vulnerable somatic mutation. Healed intracranial arterial dissections, in our experience, usually have an aggressive clinical manifestation, and the healed vascular architectures remain their shapes unless they are occluded. As a matter of fact, arterial dissection in adulthood is less likely to be the etiology of this abnormality.

In our database, we have two out of five cases that presented with acute subarachnoid hemorrhage, which underwent endovascular coiling and surgical clipping with occipital artery-posterior cerebral artery (PCA) bypass. Both of them go well on the follow-up until the present time. On the other hand, Brinjikji et al. reported that most of the cases in their series are incidental findings, although the minority presented with thunderclap headache and transient ischemic attack. None presented with acute hemorrhage. This vascular abnormality is exceedingly rare; therefore, we cannot conclude that the natural history of this distinguished arterial disease is benign. We completely agree with the readers that these patients need to be stressing the importance of radiological and clinical follow-up. The invasive management, either endovascular or surgery, should be done selectively only in the indicative patient.