Angioarchitecture of Extracranial Arteriovenous Malformations A Vascular Casting Study

Purpose: Arteriovenous malformations (AVMs) are congenital vascular anomalies, not proliferative neoplasms, but tend to behave aggressively with unpredictable growth and tissue destruction. For the understanding of the angioarchitecture of extracranial AVM, which is believed to be the main cause that explains all presenting symptoms, the study aimed to elucidate the vascular structure of extracranial AVM with vascular cast of completely excised AVM lesion. Methods: From 1996 to 2011, a total of 289 cases with extracranial AVM received surgical or surgery-based treatment by the authors in the department, excluding cases that received embolization alone. Among them, 10 patients (4 female cases, 6 male cases) were involved in this study. All the AVM nidi were excised and injected with resin through feeding arteries, then the corrosion casts were made for dimensional measurement. Results: Arteriovenous malformation nidus was comprised of multilevel branched blood vessels. We measured the diameter of predominant trunk and primary level branch vessels. The diameter of predominant trunk ranged from 2.0 (0.2) to 4.3 (0.2) mm, whereas primary level branch vessels from 1.0 (0.1) to 2.0 (0.2) mm. Seventy percent of AVM casts included trunk blood vessels with the maximal diameters ranged from 4 to 12 mm, and an average of 7.0 mm (SD, 0.93; n = 10). In this series, the smallest blood vessel visible in the cast was approximately 0.2 mm in diameter, whereas balloon-like serious dilated vessels from 10.2 to 25.4 mm. Conclusions: Vascular casting study shows us more informative, realistic, and objective 3-dimensional angioarchitecture than digital subtract angiography, 3-dimensional computed tomography angiography, and magnetic resonance angiography, not only for the facilitation of treatment decision but also for the purpose of education and research.