# Rapidly Progressive Contralateral Internal Carotid Artery Stenosis After COVID-19 Infection in a Down Syndrome Patient With Unilateral Moyamoya Arteriopathy

## TL;DR

A Down syndrome patient with moyamoya arteriopathy developed rapid artery narrowing after a COVID-19 infection and possible vascular injury.

## Contribution

This case highlights how moyamoya arteriopathy may rapidly progress after infections like COVID-19 and vascular procedures.

## Key findings

- A patient with moyamoya arteriopathy developed contralateral ICA and ACA stenosis after a positive COVID-19 test.
- The stenosis progression may be due to a combination of preexisting moyamoya, vascular inflammation, and possible thrombectomy injury.
- Close monitoring is essential in moyamoya patients exposed to triggers like infections or vascular procedures.

## Abstract

Moyamoya arteriopathy is a condition where chronic, progressive stenosis of large intracranial arteries, primarily of the anterior circulation, results in ischemia and the growth of small, abnormal collateral vessels. There is increasing evidence that infectious pathologies, such as COVID-19, may serve as a sort of trigger, or “second hit," for the development of moyamoya arteriopathy. In this article, we present the case of a 13-year-old female with Down syndrome and unilateral moyamoya arteriopathy who developed contralateral internal carotid artery (ICA) dissection and thrombus in the setting of a positive COVID-19 test and subsequently developed rapidly progressive contralateral ICA and bilateral anterior cerebral artery (ACA) moyamoya-like stenosis. The rapidly progressive contralateral ICA and bilateral ACA moyamoya-like stenosis are likely multifactorial in nature. The contralateral ICA may have had a predisposition for injury and stenosis due to the preexisting moyamoya arteriopathy, making stenosis more likely after COVID-19-induced vascular inflammation and injury as well as after a possible thrombectomy-associated injury. Based on this presentation, patients with moyamoya arteriopathy may be at risk for rapid progression of their moyamoya pathology when exposed to catalysts, including infection, such as COVID-19, and vascular injury, such as thrombectomy-induced injury. In these circumstances, high suspicion and close monitoring are essential for addressing ischemia related to the stenosis before permanent injury.