STROKE AND HAEMORRHAGE Flashcards
Define stroke.
A syndrome of rapid onset of cerebral deficit (usually focal) lasting more than 24 hours or leading to death, with no apparent cause other than a vascular one.
Define transient ischaemic attack.
A brief episode of neurological dysfunction due to temporary focal cerebral or retinal ischaemia without infarction. TIAs may herald a stroke.
What are the main two underlying causes of a stroke?
Infarction or haemorrage
What are the different causes of an ischaemic stroke (rather than a haemorragic stroke)?
Thrombotic event Large artery stenosis Small vessel disease Cardio-embolic Hypoperfusion
What are the two types of haemorrhagic stroke?
Intracerebral haemorrhage
Subarachnoid haemorrhage
How does large artery stenosis cause an ischaemic stroke?
Usually causes a stroke by acting as an embolic source rather than by occlusion of the vessel (which may not in itself cause stroke if it occurs gradually and collateral circulation is adequate)
What are the main sites of stenosis in the large arteries leading to the head?
Stenosis occurs most often at arterial branch points.
4 most common sites in order: Common carotid Internal carotid Vertebral artery Subclavian artery
Is the caucasian population more or less affected by strokes than the non-caucasian population?
Non-caucasian population tend to have more intracranial narrowing and white populations tend to have more extracranial disease (coronary artery and peripheral artery disease)
What is lipohyalinosis?
Small-vessel disease in the brain characterised by vessel wall thickening and a resultant reduction in luminal diameter. Recent evidence suggests that endothelial dysfunction as a result of inflammation is the most likely cause for it. This may occur subsequent to blood–brain barrier failure, and lead to extravasation of serum components into the brain that are potentially toxic. Lacunar infarction could thus occur in this way, and the narrowing – the hallmark feature of lipohyalinosis – may merely be a feature of the swelling occurring around it that squeezes on the structure.
What is a cardio-embolic stroke?
Stroke caused by emboli originating in the chambers of the heart.
What is the most common cause of cardio-embolic stroke?
Atrial fibrillation causing thrombosis in a dilated left atrium.
Other than AF, what are the other causes of cardio-embolic stroke?
Cardiac valve disease (including congenital valve disorders) Infective vegetations Rheumatic and degenerative changes Mural thrombosis in damaged ventricle Patent foramen ovale may allow fragments of venothrombus through to left side when performing Valsava causes shunting. Pulmonary arteriovenous fistulas Fat emboli after long bone fracture Atrial myxoma (tumour) Iatrogenic causes (e.g cardiac bypass)
What area of the brain is particularly vulnerable to stroke from hypoperfusion as a result of cardiac arrest?
Parieto-occipital area between middle and posterior cerebral artery. Hypoperfusion usually leads to borderzone infarction in the watershed areas between vascular territories, particularly if there is severe stenosis of proximal carotid vessels.
What is most common cause of transient ischaemic attacks?
Micro-emboli from cardiac thrombus and atheromatous plaques/thrombus within the aortic arch, carotid and vertebral systems.
What are the main risk factors for stroke?
Hypertension Smoking Sedentary lifestyle Alcohol High cholesterol Atrial fibrillation Obesity Diabetes Severe carotid stenosis Obstructive sleep apnoea (leading to cardiac damage and cardiac-emboli)
What are the less common risk factors and rarer causes of stroke?
Thrombocythaemia, polycythaemia and hyperviscosity states. Antiphospholipid syndrome. Low-dose oestrogen containing oral contraceptices in the presence of other risk factors. Migraine Vasculitis Amyloidosis Neurosyphilis Sympathomimetic drugs such as cocaine
What is CADASIL (cerebral dominant arteriopathy with subcortical infarcts and leucoencephalopathy)?
The most common form of hereditary stroke disorder, and is thought to be caused by mutations of the Notch 3 gene on chromosome 19. The disease belongs to a family of disorders called the Leukodystrophies. The most common clinical manifestations are migraine headaches and transient ischemic attacks or strokes, which usually occur between 40 and 50 years of age, although MRI is able to detect signs of the disease years prior to clinical manifestation of disease.
What are the features of a transient ischaemic attack due to an occlusion of the carotid system?
Amaurosis fugax Aphasia Hemiparesis Hemisensory loss Hemianopic visual loss
What is amaurosis fugax?
Sudden transient loss of vision in one eye. When due to the passage of emboli through the retinal arteries, arterial obstruction is sometimes visible through an opthalmoscope. Associated feature of a TIA.
What is aphasia?
Problems with language
What is hemianopic visual loss?
Loss of one visual field most often in both eyes.
What are the features of a transient ischaemic attack due to an occlusion of the vertebral system?
Diplopia Vertigo Vomiting Choking and dysarthria Ataxia Hemisensory loss Hemianopic visual loss Bilateral visual loss Tetraparesis Loss of consciousness (rare) Transient global amnesia
