Extracellular matrix remodeling and internal elastic lamina alterations in cerebral arteriovenous malformations:...

Cerebral arteriovenous malformations (cAVMs) are high-flow vascular lesions associated with a relevant risk of intracranial hemorrhage. Beyond angioarchitectural determinants, emerging evidence suggests that alterations of the internal elastic lamina (IEL) and elastic fiber network may contribute to vascular remodeling and structural instability. We conducted a structured qualitative literature review with narrative synthesis, without quantitative meta-analysis because of substantial methodological and biological heterogeneity across studies. We included histological, molecular, and genetic investigations addressing elastin biology, IEL structure, extracellular matrix remodeling, and related signaling pathways in cAVMs within the broader context of vascular wall biology. Twenty studies met the predefined inclusion criteria. Direct histopathological evidence of IEL fragmentation was identified in only two primary studies, whereas additional histological investigations reported structural abnormalities including IEL disorganization, interruption, or irregular thickening. Molecular studies consistently described dysregulation of KRAS-MAPK, Notch, and BMP9/ALK1 signaling pathways involved in vascular endothelial homeostasis and extracellular matrix remodeling, although most did not directly evaluate IEL or elastic fiber architecture. Collectively, these findings support biologically plausible mechanisms of vascular remodeling rather than a unified mechanistic cascade. Similarities with inherited disorders affecting elastogenesis represent mechanistic analogies rather than evidence of shared disease pathogenesis. Alterations of the IEL and elastic fiber network may represent a relevant component of the structural phenotype of cAVMs, potentially acting as downstream or parallel manifestations within a multifactorial biological framework. Integrating histopathological and molecular evidence may improve the biological characterization of these lesions and support future hypothesis generation regarding vascular stability. However, the currently available evidence does not allow causal inference regarding the role of IEL alterations or elastic fiber disruption in cAVM pathogenesis or rupture susceptibility.