Multimodal MRI of Cerebral Small Vessel Disease

Abstract

Cerebral small vessel disease (cSVD) is a spectrum of clinical and imaging abnormalities linked to the pathology of small penetrating arteries and arterioles in the brain irrigating subcortical structures1. Accumulating data suggest that cSVD is the most prevalent neurological disorder in the ageing society of the developed world2, 3. The prevalence of its seemingly asymptomatic manifestations –silent brain infarctsincreases with age from approximately 6-7% at 60 years to 28% at 80 years of age according to a recent review4. In another study lacunar infarcts were found in 23% of all subjects over 65 years, and in 43% of subjects over 80 years of age5. Its acute, symptomatic manifestations –lacunar strokesaccount for approximately 20% of all ischemic strokes6-8. Thus improved management of cSVD based on better understanding of the disease is of great importance. cSVD is characterised by the arteriolosclerosis and/or microatheromatosis of small calibre (50-500 μm) cerebral arterial vessels caused by various pathologies1. Its most common, sporadic form is related to age and vascular risk factors including hypertension and diabetes in particular. Inherited forms are increasingly recognised with CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) being the most prevalent genetic cSVD caused by the mutation of NOTCH 3 gene encoding a transmembrane receptor of vascular smooth muscle cells9, 10. CADASIL -affecting young to middle aged, otherwise healthy individualsprovides a pure model for cSVD and therefore has been extensively studied 11. Inflammatory, infective and immunologically mediated forms are usually part of systemic diseases of diverse origin characterised by central nervous system vasculitis 12. Cerebral amyloid angiopathy (CAA) –a pathological hallmark of Alzheimer’s diseaseaffects small vessels both cortically and subcortically and may also lead to ischemic changes, although it is particularly associated with recurrent lobar haemorrhages12. In this chapter we will only focus on the most common and well studied age and vascular risk factor related form of cSVD and CADASIL. cSVD predominantly affects perforating end-arteries branching usually perpendicularly from a large parent artery. These penetrating arteries irrigate the so called perforator areas including the basal ganglia and internal capsule (lenticulostriate arteries from the anterior cerebral artery (ACA) A1 segment and middle cerebral artery (MCA) M1 segment), the