40. Cerebrovascular diseases, intracranial hemorrhages

What is cerebrovascular diseases?

Any pathological disease of the brain, that involves blood vessels

What is a stroke?

Clinical diagnosis that involves acute neurological symptoms

- caused by a cerebrovascular event

Types of stroke?

Ischemic and hemorrhagic

Ischemic stroke is also called?

Encephalomalacia

Ischemic stroke? why

Occurs when there is liquefactive necrosis of the brain parenchyme

- due to ischaemia

How can we classify ischemic strokes?

- Based on cause

- Based on morphology

Based on cause?

- Localized ischaemia

- Global ischaemia

Localized ischaemia causes?

- Embolism

- Microangiopathy

- Thrombosis

- Vasculitis

Global ischaemia causes?

- Severe hypotension

- Hypoxaemia

Pathogenesis of global ishcaemia?

Usually damage the hippocampus and Purkinje-cells first

- later, watershed infarct will develop

What is watershed infarct?

Special type of infarct, where the zones most distal to the arteries they are supplied by become necrotic

- often occurs on the border zone between the area supplied by the anterior and middle cerebral arteries

Ischemic stroke based on morphology?

- Encephalomalacia alba

- Encephalomalacia flava

- Encephalomalacia rubra

Encephalomalacia alba?

Usually occurs when there is a thrombus blocking the arterial supply of a portion of brain parenchyme

- develops into flava

Encephalomalacia flava?

Develops from alba (after a few weeks), as macrophages digest the liquefactive necrosis

Encephalomalacia rubra?

Usually occurs when there is an embolus blocking the arterial supply of a portion of the brain parenchyme

Why will a emboli lead to rubra, when a thrombus lead to flava?

These emboli often lyse, allowing the necrotic area to be reperfused

- the reperfused blood cause the redness

Haemorrhagic stroke? why

Occurs when a rupture of an artery cause intracerebral, or subarachnoid haemorrhage

- will increase the intracranial pressure

Most common causes of intracerebral haemorrhage?

- Hypertension

- Cerebral amyloid angiopathy

- Ruptured arterio-venous malformations

Most common cause of subarachnoid haemorrhage?

Rupture of berry aneurisms

What is a berry aneurysm?

Saccular outpouching of vessels in the circle of Willis, usually at bifurcations

Risk factors for berry aneurysms?

- Hypertension

- Smoking

- Collagen disorders, like Ehlers-Danlos and Marfan syndrome

What is a traumatic brain injury?

Physical damage to the brain, caused by external impact

Examples of traumatic brain injuries?

- Epidural haematoma

- Subdural haematoma

- Contusion

- Concussion

- Diffuse axonal injury

- Chronic traumatic encephalopathy

What is an epidural haematoma?

Bleeding between the dura mater and the skull

- often caused by a rupture of the middle meningeal artery

What is a subdural haematoma?

Bleeding between the dura and arachnoid mater

- caused by rupture of the bridging veins

What is chronic subdural haematoma?

The presence of multiple organized subdural haematomas

What is a contusion?

"Bruising" of the brain parenchyme

- characterized by small haemorrhage, tissue injury and oedema

Contusion at the site of impact? and opposite

- Site of impact = coup injury

- Opposite side of impact = countercoup injury

What is a concussion?

A state of temporary altered consciousness from a head injury, without any contusion

= mild traumatic brain injury

What is diffuse axonal injury?

Widespread microscopic damage, primarily to the axons

- depending on severity, it can cause altered mental state and potentially coma