Mechanisms & Management of Stroke Flashcards
What is a stroke?
- Sudden, focal neurological syndrome due to cerebrovascular disease
- Causes neuronal cell death & brain damage
What are the three classifications of stroke?
Haemorrhagic:
- Bleeding into the brain from a vessel rupture
Ischaemic (80%):
- Occlusion of blood supply to a region of the brain
Transient Ischaemic Attack (TIA):
- Focal/global disturbance of cerebal function lasting < 24 hrs
What percentage of oxygen does the brain consume at rest?
25%
What blood vessels supply oxygen to the proximal part of the brain?
Internal carotid arteries & vertebrobasilar system (combine to form Circle of Willis)
What blood vessels supply oxygen to the distal part of the brain?
- Middle cerebral artery (MCA)
- Anterior cerebral artery (ACA)
- Posterior cerebral artery (PCA)
What are the two types of haemorrhagic stroke?
- Intracerebral: Bleeding in brain tissue
- Subarachnoid: Bleed between two layers of dura (arachnoid and pia mater)
What are the two types of ischaemic stroke?
- Large vessel disease: Internal carotid, vertibrobasilar system
- Small vessel disease: MCA, ACA, PCA
What are the causes of ischaemic stroke?
- Embolism (DVT, PE)
- Hypoperfusion
- Hyperviscosity or hypercoagulability
What is the main cause of intracerebral haemorrhage?
- Spontaneous haemorrhage into brain
- Mostly due to hypertension
Where is an intracerebral haemorrhage commonly located?
- Deep within brain, either in basal ganglia or cerebrellum/pons
- Can lead to displacement of midline structures
How is the volume of haemorrhage related to mortality?
- Prognosis depends on size & location
- Volume > 60mL has > 90% mortality
How is the type of stroke determined?
- Imaging with CT or MRI
- No major distinguishing clinical features for haemorrhagic & ischaemic
What are the risk factors for haemorrhagic stroke?
- Hypertension
- Vascular malformations (aneurysms, AVMs)
- Bleeding disorders (haemophilia, leukemia)
- Anticoagulant meds
- Tumours
- Illicit drugs (cocaine, amphetamines)
What does ischaemic stroke cause?
- An area of infarction (cell death)
- Symptoms depend on vascular territory involved
Which type of stroke has better mortality rates?
Ischaemic
What are the risk factors for ischaemic stroke in large vessels?
Artherosclerosis
- Age
- Hypertension
- Physical activity
- High cholesterol
- Smoking
- Diabetes
- Obesity
- Family history
Carotid artery disease Pregnancy Haematological malignancy Thrombophilic disorders Vasculitis
What are the risk factors for ischaemic stroke in small vessels & cardiac embolism?
Lacunar (small vessels)
- Hypertension
Cardiac embolism
- Atrial fibrilation
- Cardiomyopathy
- Endocarditis
What do the clinical manifestations of stroke depend on?
Blood vessel and area of brain affected
Where are the centres for motor control and sensation located?
- Motor control: Pre-central sulcus
- Sensation: Post-central sulcus
What are the roles of the temporal, parietal and frontal lobes?
- Temporal: Memory, emotions, hearing, speech
- Parietal: Spatial awareness/orientation, arithmetic, visual memory
- Frontal: Executive level thinking, motor planning, continence, speech
What are the roles of the cerebellum & brainstem?
- Cerebellum: Coordination
- Brainstem: Basic homeostatic mechanisms & reflexes (respiration, HR, sleep)
Where is the most common area of stroke?
MCA - supplies two thirds of the brain
What are the roles of the dominant and non-dominant hemispheres?
- Dominant (usually L): Speech & cognition
- Non-dominant: Processing non-verbal stimuli
What are the typical clinical symptoms of an MCA stroke?
- Contralateral strength & sensory loss
- Neglect
- Hemianopia (blindness in one field of vision)
- Dysphasia (language impairment)
- Apraxia (difficulty performing actions)
What are the typical clinical symptoms of an ACA stroke?
- Isolated contralateral leg strength loss
- Aphasia
- Urinary incontinence
What are the typical clinical symptoms of an PCA stroke?
Hemianopia
What are the typical clinical symptoms of basilar, lacunar and posterior cerebellar artery strokes?
- Basillar: Coma, 40% mortality, bilateral motor weakness
- Lacunar: Pure motor weakness/sensory loss
- Posterior cerebellar artery: Coordination loss
What does the acute phase medical treatment for a stroke consist of?
- Revascularisation therapy: Thrombolysis, intra-arterial TPA/clot retrieval
- Aspirin
- Supportive care
- Stroke unit admission (highly effective)
What does supportive care involve?
- Maintain hydration
- Early speech assessment to prevent aspiration pneumonia
- Treat fever aggressively
- Treat hyperglycaemia
What does the subacute phase medical treatment & secondary prevention for a stroke consist of?
- Blood pressure management (ACE inhibitors)
- Antiplatelet agents (aspirin)
- Cholesterol lowering
- Carotid endarterectomy
- Anticoagulation
What are the benefits of rehabilitation following a stroke?
- Essential for recovery
- Early mobilisation shown to improve outcomes
What are some of the sensory and motor impairments following stroke?
- Sensory: Loss of tactile sensation/kinaesthesia
- Motor: Loss of strength/dexterity, spasticity, contracture
What are some of the physio management strategies for stroke?
- Strength training
- Sensory retraining
- Activity training
- Management of contracture & spasticity
- Prevention of secondary complications (CV fitness, pain, swelling, shoulder subluxation)
