Stroke Flashcards
What is a stroke?
Clinical syndrome
Caused by sudden interruption of blood supply to the brain
Leads to rapidly developing focal or global neurological disturbances lasting > 24 hours
What is a TIA?
A “mini-stroke”
Very similar symptoms to stroke but last < 24 hours
Most resolve within 1-2 hours
What are the different kinds of stroke?
Ischaemic (85%)
Haemorrhagic (15%)
- 10% strokes due to primary haemorrhage
- 5% due to SAH
What is the epidemiology of stroke (overall)?
- The first episode of stroke affects approximately 230 in 100,000 people per year in the UK
- > 80,000 people in England and Wales are admitted to hospital with acute stroke each year
What is the epidemiology of TIA?
Incidence of the first episode of TIA = ~ 50 in 100,000 people in the UK annually
Name rarer causes of strokes
Cerebral venous thrombosis - commonly seen in pts with prothrombic tendency (e.g., pregnancy, infection, inherited thrombophilia, dehydration, malignancy, primary intercranial HTN)
Carotid artery dissection
What is the pathophysiology of an ischaemic stroke?
- Occlusion of an intracranial vessel → reduced blood flow to the brain regions supplied by the vessel
- Leads to decreased oxygen supply and infarction in that region
- Focal cerebral infarction occurs via two distinct pathways
1. necrotic pathway with a rapid cytoskeletal breakdown
2. apoptotic pathway where ischaemia leads to necrosis and cells become programmed to die, leading to cellular depolarization and free radicals production, causing disruption in the vital functioning of the cells
How quickly do brain tissues die when cerebral blood flow is reduced to 0?
4-10 minutes
What flow value causes brain tissue infarction in an hour?
< 16-18ml/100g tissue per min
What flow value causes brain tissue ischaemia without infarction?
< 20 ml/100g tissue per min causes ischaemia without infarction unless prolonged for several hours
What is the aetiology of an ischaemic stroke?
*Thrombotic (includes lacunar strokes and large vessels occlusions) = atherosclerosis
*Embolic = atrial fibrillation (most common) - also in pts with valvular defect and endocarditis
What is the aetiology of a haemorrhagic stroke?
- Intracranial haemorrhages = uncontrolled HTN (most common)
- Subarachnoid haemorrhages - may occur as a result of AV malformations, berry aneurysms (which occur more commonly in patients with autosomal-dominant polycystic kidney disease) and cerebral angiomas
What is the pathophysiology of a haemorrhagic stroke?
- Spontaneous rupture of small, penetrating arteries deep inside the brain causes disturbance of white matter and neuronal activities within the brain
- Haemorrhagic collections act as mass lesions, causing compression and raised pressure leading to neurological deficits
What is the pathophysiology of TIA?
Acute occlusion of an intracranial vessel
↓
↓blood flow to the brain region supplied by the vessel
↓
decreased oxygen supply and infarction in that region
↓
blood flow returns to normal within 24 hours = resolution of symptoms
What are symptoms of stroke (in general)?
Headache (very sudden - reaches max intensity within 5 mins in SAH)
Slurred speech
Facial weakness
Facial/neck pain
Weak arms and legs (often sudden)
Altered taste and smell
Loss of vision
Urinary incontinence
Confusion/altered level of consciousness/syncope
Impaired pain/temperature sense
Cranial nerve deficit (e.g., Horner syndrome)
What are symptoms of a left hemisphere stroke?
- aphasia
- right-sided sensory loss
- right-sided hemiparesis
- right-sided visual field defect
- dysarthria
- difficulty in calculation
- difficulty writing
What are symptoms of a right hemisphere stroke?
- left-sided sensory loss
- left-sided hemiparesis
- left-sided gaze disturbances
- aphasia
- dysarthria
- spatial disorientation
What is the most commonly used classification system for ischaemic stroke? What does it include?
Bamford classification (a.k.a. Oxford classification system) - categorises strokes based on the initial presenting symptoms and clinical signs
Includes :
*Total anterior circulation stroke (TACS)
*Partial anterior circulation stroke (PACS)
*Posterior circulation syndrome (POCS)
*Lacunar stroke (LACS)
Name the Posterior circulation syndromes (POCs) signs
- cranial nerve impairment
- unilateral or bilateral motor or sensory deficit
- disorder of conjugate eye movement
- cerebellar dysfunction
- homonymous hemianopia (with macular sparing)
- cortical blindness
Name the Total anterior circulation syndromes (TACSs) signs
- hemiplegia and homonymous hemianopia contralateral to the lesion
- aphasia or visuospatial disturbance
- sensory deficit contralateral to the lesion
Name the Partial anterior circulation syndromes (PACSs) signs
Two of the following need to be present for PACS diagnosis
*unilateral weakness (and/or sensory deficit) of the face, arm and leg
*homonymous hemianopia
*higher cerebral dysfunction (dysphasia, visuospatial disorder)
N.B. higher cerebral dysfunction alone is also classified as PACS
What is a lacunar stroke?
Subcortical stroke
Occurs secondary to small vessel disease
No loss of higher cerebral functions (e.g., dysphasia)
Name the Lacunar stroke (LACS) signs
One of the following need to be present for a diagnosis of LACS
- pure sensory stroke
- pure motor stroke
- sensori-motor stroke
- ataxic hemiparesis
What investigations can be done a person with suspected stroke?
Bedside
-ECG (esp. looking for atrial fibrillation)
Bloods
-Baseline (FBCs, U+Es, LFTs, inflammatory markers)
-Coagulation profile
-Blood glucose
Imaging
-CT head – initial investigation of choice