Moyamoya-Type Collaterals in ACTA2 p. Arg179 Related Arteriopathy: Challenging the Paradigm of Absent Neovascularization-A Longitudinal DSA Study.

Abstract

Background and purpose: ACTA2 p. Arg179 variants can cause a distinctive cerebrovascular arteriopathy historically described lacking classic moyamoya basal collaterals. Limited data on collateral architecture and surgical outcomes have led to uncertainty regarding revascularization strategies. The purpose of this study is to provide a systematic longitudinal DSA assessment of collateral patterns and postoperative findings in pediatric ACTA2-associated cerebrovascular disease.

Material and methods: Ten pediatric patients with genetically confirmed ACTA2 mutations underwent DSA imaging. Eight consecutive patients with neurological instability and confirmed hemodynamic compromise underwent surgical revascularization (indirect or combined direct-indirect). Two patients with stable neurological status were managed conservatively. Paired DSA (7 patients) and magnetic resonance angiography (5 patients) were performed at baseline and follow-up of the operated cohort. Collaterals were classified as classic moyamoya-type, distal moyamoya-type, leptomeningeal, or duropial. Postoperative revascularization was graded using Matsushima classification.

Results: Mean baseline vessel calibers demonstrated marked proximal ectasia (petrous ICA 8.4 ± 2.8 mm vs. normative 3.8 ± 0.4) transitioning to distal stenosis (supraclinoid ICA 2.6 ± 0.7 mm vs. normative 3.3 ± 0.3). Classic moyamoya-type collaterals were present in 2 patients at baseline and in 5 patients at follow-up. Postoperative Matsushima grading demonstrated Grade A/B in 6 patients, with surgical collateralization remaining patent and sufficient up to 14 years.

Conclusions: ACTA2 p. Arg179 related cerebral arteriopathy demonstrates moyamoya-type collaterals challenging the historical paradigm of absent collateralization. Robust surgical neovascularization comparable to idiopathic moyamoya may support revascularization in symptomatic pediatric patients with confirmed hemodynamic compromise.