3. Cerebrovascular diseases Flashcards
Types of cerebrovascular disease
- Cerebral Ischemia
- Cerebrovascular accidents (cerebral infarction)
- Intracranial haemorrhages
- Vascular malformations
Definition of cerebral ischemia
The brain receives 15% of resting cardiac output & accounts of 20% of total body oxygen consumption, a highly aerobic, oxygen-limiting tissue which can be deprived of oxygen by various mechanisms
Causes of cerebral ischemia
- Global Cerebral Ischemia
- Due to generalized reduction of cerebral perfusion (cardiac arrest, shock, severe hypotension) - Focal Cerebral Ischemia
- Due to reduction of blood flow to a localized area of
the brain (thrombosis, embolism, vasculitis)
Pathological effects & complications of cerebral ischemia
- Cortical laminar necrosis
- Preservation of some layers of the cortex & involvement of others - Border zone/watershed infarct
- Occurs at area of supply by anterior & middle cerebral arteries
- Produces a sickle-shaped band of necrosis over the cerebral convexity a few centimeters lateral to the interhemispheric fissures
Definition of cerebrovascular accidents (cerebral infarction)
Commonly known as ‘strokes’; sudden focal brain necrosis (cerebral infarction) due to complete & prolonged cerebral ischemia; clinically categorized as ischemic or hemorrhagic infarction
Etiologies and associations with cerebrovascular accidents (cerebral infarctions)
- Hypertension
- Diabetes mellitus
- Atherosclerosis
- Transient ischemic attack (TIA)
- Brief episodes of non-traumatic neurological defect due to focal brain or retinal ischemia (usually <1h) - Cardiac arrhythmias (e.g. atrial fibrillation)
- Vascular malformations
- Berry aneurysms
- Arteriovenous malformations
2 types of CVA/Cerebral infarction
- Ischemic infarction
2. Hemorrhagic infarction
Types of ischemic infarction
- Thromotic infarcts (mostly due to atherosclerosis,
commonly found in the carotid bifurcation, origin of middle cerebral artery & either end of the basilar artery) - Embolic infarcts (thromboembolism from cardiac arrhythmias, vegetations from valvular diseases like infective endocarditis, fat emboli from long bone fractures; most commonly lodges in middle cerebral arterial branches)
- Lacunar infarcts (due to arteriolar sclerosis secondary to hypertension, multiple small cavitary infarcts which occur in the basal ganglia, internal capsule, thalamus & pons)
- Paradoxical embolic infarcts (venous thromboemboli passing directly back into systemic circulation via cardiac abnormalities, particularly in children)
Hemorrhagic infarction
Essentially results from anything that causes an intracerebral hemorrhage
Morphology of ischemic infarct
- Bland area of infarct
- Punctate hemorrhages reflecting ischemia - reperfusion injury
- Possible causes: thrombosis, embolism
Morphology of hemorrhagic infarct
- Hemorrhagic area of infarct
2. Possible causes: hypertension, Charcot-Bouchard aneurysms, arteriovenous malformations
Morphology of lacunar infarct
- Small cavitary infarcts
- Usually found in basal ganglia, internal capsule, thalamus & pons
- Possible causes: hypertension
Morphology of shower embolisation
- Widespread white matter petechial hemorrhages
- Characteristic of fat emboli (bone marrow embolization)
- Differentials: malaria, vasculitis, acute hypertensive encephalopathy
Pathological effects and complications of cerebrovascular accidents (cerebral infarction)
- Sudden focal deficit
- Signs of raised intracranial pressure (vomiting, nausea, headache)
- Multi-infarct dementia
- Clinical syndrome characterized by progressive dementia, gait abnormalities, pseudobulbar signs & superimposed focal deficits over the course of many months or years
- Pathological basis: multiple bilateral gray matter (cortex, basal ganglia, thalamus) & white matter (centrum semiovale) infarcts
- Contributors to infarcts include cerebral atherosclerosis, thromoembolic events & cerebral arteriolar sclerosis from chronic hypertension
Investigative modalities for cerebral infarction
- Non-enhanced CT scan: to determine type of infarct
(ischemic appears hypodense, hemorrhagic appears
hyperdense) - CT/MRI angiogram: to determine location of infarct
- Perfusion imaging: to determine penumbra
Radiological interventions for cerebral infarction
- Thromoembolic clot: arterial thrombolysis or balloon guide catheter-assisted clot removal
- Cerebral aneurysm: balloon-assisted Guglielmi detachable coil placement
- Arteriovenous malformations: embolization with Onyx liquid
Definition of intracranial haemorrhage
Can be classified as being intra-axial (intracerebral/intraparenchymal) & extra-axial (subarachnoid, subdural, epidural)
Types of intracranial haemorrhage
- Intracerebral (Intraparenchymal) Hemorrhage
- Subarachnoid Hemorrhage
- Subdural Hemorrhage
- Epidural (extradural) Haemorrhage
Definition of intracerebral (intraparenchymal) haemorrhage
Hemorrhage within the brain parenchyma
- Involves small intraparenchymal vessels
- Non-enhanced CT scan: localized hyperdense lesion within brain parenchyma
Causes of intracerebral haemorrhage
- Hypertension (most common cause, results in weakening of arteriolar walls)
- Cerebral amyloid angiopathy (deposition of amyloid in vascular walls which weakens them)
- Ruptured arteriovenous malformation
- Ruptured Charcot-Bouchard aneurysm (due to chronic hypertension, occurs in the basal ganglia, internal capsule, thalamus & pons)
- Trauma
- Venous sinus thrombosis
- Coagulopathy
Pathological effects and complications of intracerebral haemorrhages
Hemorrhagic stroke
Definition of subarachnoid haemorrhage
Hemorrhage into the subarachnoid space (space containing CSF, between pia & arachnoid mater)
- Involves cerebral arteries found within the subarachnoid space
- Non-enhanced CT scan: hyperdense lesion tracking into the sulci of the brain
Causes of subarachnoid haemorrhage
- Ruptured berry aneurysms (aka saccular aneurysms,
mostly found within the anterior circulation of the circle of Wilis; associated with polycystic kidney disease & aortic coarcation) - Ruptured arteriovenous malformation
- Extension from other intracranial hemorrhages
(traumatic hematoma, intracerebral hemorrhage into
ventricular system)
Pathological effects & complications of subarachnoid haemorrhage
- Thunderclap headache
- Additional ischemic damage (due to vasospasm of
vessels bathed in extravasated blood) - Meningeal fibrosis & scarring (can lead to
obstructive hydrocephalus if it involves the foramina of Luschka & Magendie or non-obstructive hydrocephalus if it involves the arachnoid granulations)
