Novel Vascular Anastomoses and Moyamoya Disease in a Woman with Down Syndrome

Abstract

A 56-year-old woman with Down syndrome presented with right-sided weakness and dysarthria, and was found on CT/CTA to have a left middle cerebral artery infarct secondary to moyamoya disease. Her left posterior inferior cerebellar artery (PICA) was fed both by the left vertebral artery, and the left ascending pharyngeal artery (APA), with a variant origin from the internal carotid artery (ICA), then passing through the jugular foramen (Figure 1). Her right PICA originated exclusively from her right occipital artery, also via the jugular foramen (Figure 2). The left vertebral artery originated directly from the aortic arch, whereas the right vertebral artery originated from the brachiocephalic trunk. In addition, she had a trifurcated anterior cerebral artery (ACA), and just prior to this trifurcation, her left ACA was partially supplied by the left ICA, via a superior hypophyseal artery. This case is noteworthy for several reasons. First, though it is exceedingly rare to have the PICA supplied by the jugular branch of the APA, this is the first reported case with an ICA origin of that APA.1,2 The fact that both PICAs in this patient originate from the anterior circulation should remind clinicians that in unexplained posterior circulation infarctions, vascular anatomy should be explored, as carotid-vertebrobasilar anastomoses such as these are rare, but possible. Lastly, the conjunction of moyamoya disease and anomalies of the vertebrobasilar system in a patient with Down syndrome raises interesting questions about the influence of trisomy 21 on the developing vasculature. Connections from the APA to the vertebrobasilar system are hypothesized to result from a lack of regression of an embryological anastomosis, in line with the more common persistent trigeminal and persistent hypoglossal arteries.1 Patients with moyamoya disease have a significantly higher rate of persistent carotid-vertebrobasilar anastomoses than the general population,3 and are also 26 times more likely to have Down syndrome.4 Correspondingly, patients with Down syndrome have significantly higher levels of moyamoya disease, and are more than 10 times as likely as the general population to have abnormalities of the Circle of Willis5 and vertebral arteries.6 Several genes on chromosome 21 are known to affect angiogenesis, namely collagen XIII/endostatin (COL18A1), DYRK1A, and Down syndrome candidate region 1 (DSCR1), possibly through inhibition of VEGF activity.7 Whether additional copies of these genes are responsible for the anomalous vascular development seen in Down syndrome, in turn predisposing to the development of moyamoya disease, could benefit from further exploration.

High-resolution magnetic resonance vessel wall imaging provides new insights into Moyamoya disease

“…HR-VWI has higher imaging clarity and precision and can visualize the subtle changes in the vessel wall. CTA scanning is fast, but requires injection of contrast medium and, a higher radiation dose, and the MMV display at the base of the skull is easily interfered with by the skull bone ( Byworth et al, 2021 ). HR-VWI is non-invasive and radiation-free compared to the other detection methods.…”

Progression in Moyamoya Disease: Clinical Features, Neuroimaging Evaluation, and Treatment

“…Identical twins have a higher rate of MMD co-prevalence, and the offspring of MMD patients are about 34 times more likely to develop MMD than the general population [ 30 ]. Some cases have been reported to have co-existing MMD and genetic diseases, such as Down syndrome, neurofibromatosis and Turner syndrome, were reported [ 31 , 32 ]. Multiple systems and organs are involved in these genetic disorders and cerebrovascular diseases could be one of their complications.…”