Stroke: causes and clinical features

Abstract

Stroke is a clinically defined syndrome of acute, focal neurological deficit attributed to vascular injury (infarction, haemorrhage) of the central nervous system. Stroke is the second leading cause of death and disability worldwide. Stroke is not a single disease but can be caused by a wide range of risk factors, disease processes and mechanisms. Hypertension is the most important modifiable risk factor for stroke, although its contribution differs for different subtypes. Most (85%) strokes are ischaemic, predominantly caused by small vessel arteriolosclerosis, cardioembolism and large artery athero-thromboembolism. Ischaemic strokes in younger patients can result from a different spectrum of causes such as extracranial dissection. Approximately 15% of strokes worldwide are the result of intracerebral haemorrhage, which can be deep (basal ganglia, brainstem), cerebellar or lobar. Deep haemorrhages usually result from deep perforator (hypertensive) arteriopathy (arteriolosclerosis), while lobar haemorrhages are mainly caused by cerebral amyloid angiopathy or arteriolosclerosis. A minority (about 20%) of intracerebral haemorrhages are caused by macrovascular lesions (vascular malformations, aneurysms, cavernomas), venous sinus thrombosis or rarer causes; these are particularly important in young patients (<50 years). Knowledge of vascular and cerebral anatomy is important in localizing strokes and understanding their mechanisms. This guides rational acute management, investigation, and secondary prevention.

Keywords: Cerebrovascular disease; MRCP; intracerebral haemorrhage; ischaemic stroke; stroke pathogenesis; stroke risk factors; transient ischaemic attack.

© 2020 Published by Elsevier Ltd.

Figures

Figure 1

Illustration of the differences between disease processes, risk factors and mechanisms in stroke.

Figure 2

(a) Axial diffusion-weighted MRI showing an acute small subcortical infarction in the right centrum semiovale white matter consistent with a small vessel occlusion (red arrow). (b) Extracranial computed tomography (CT) angiography demonstrating ≥95% carotid stenosis (red arrow). (c) Non-contrast axial CT of the brain showing acute thrombus in the right middle cerebral artery (the ‘hyperdense MCA sign’, red arrow). (d) Resulting acute infarction showing high signal indicating restricted diffusion on axial diffusion-weighted MRI of the brain.

Figure 3

(a) Non-contrast axial computed tomography (CT) scan showing a deep intracerebral haemorrhage in the basal ganglia. (b) Non-contrast axial CT scan showing venous haemorrhagic infarction of the right temporoparietal region due to right transverse sinus thrombosis. (c) Susceptibility-weighted imaging showing lobar haemorrhage, superficial haemosiderin staining within and around cerebral sulci (cortical superficial siderosis, blue arrow), and strictly lobar parenchymal microbleeds (red arrow) consistent with CAA.