Cerebral arteriopathies of childhood and stroke - A focus on systemic arteriopathies and pediatric fibromuscular dysplasia (FMD)

Systemic vascular involvement in children with cerebral arteriopathies is increasingly recognized and often highly morbid. Fibromuscular dysplasia (FMD) represents a cerebral arteriopathy with systemic involvement, commonly affecting the renal and carotid arteries. In adults, FMD diagnosis and classification typically relies on angiographic features, like the 'string-of-beads' appearance, following exclusion of other diseases. Pediatric FMD (pFMD) is considered equivalent to adult FMD although robust evidence for similarities is lacking. We conducted a comprehensive literature review on pFMD and revealed inherent differences between pediatric and adult-onset FMD across various domains including epidemiology, natural history, histopathophysiology, clinical, and radiological features. Although focal arterial lesions are often described in children with FMD, the radiological appearance of 'string-of-beads' is highly nonspecific in children. Furthermore, children predominantly exhibit intimal-type fibroplasia, common in other childhood monogenic arteriopathies. Our findings lend support to the notion that pFMD broadly reflects an undefined heterogenous group of monogenic systemic medium-or-large vessel steno-occlusive arteriopathies rather than a single entity. Recognizing the challenges in categorizing complex morphologies of cerebral arteriopathy using current classifications, we propose a novel term for describing children with cerebral and systemic vascular involvement: 'cerebral and systemic arteriopathy of childhood' (CSA-c). This term aims to streamline patient categorization and, when coupled with advanced vascular imaging and high-throughput genomics, will enhance our comprehension of etiology, and accelerate mechanism-targeted therapeutic developments. Lastly, in light of the high morbidity in children with cerebral and systemic arteriopathies, we suggest that investigating for systemic vascular involvement is important in children with cerebral arteriopathies.