Physiology: Stroke Flashcards
Describe the characteristics of an UMN lesion. (pyramidial)
Weakness Increased Tone - spasticity Increased reflexes No wasting Upgoing plantar (positive Babinski)
List the characteristics of a LMN lesion.
Weakness Muscle Atrophy Decreased tone Decreased reflexes Normal plantar (none or flexion)
Name the issues extrapyramidal lesions cause.
Akinesia, rigidity, tremor
Name the issues cerebellar lesions cause.
Ataxia
Dysmetria (inability to control distance, speed and ROM)
Nystagmus
What would a cortical lesion produce?
UMN + language/perceptual/frontal abnormalities
What would a brainstem lesion produce?
UMN + cranial nerve deficits +/- sensory
What is a stroke?
Rapidly developing focal (sometimes global) neurological deficit due to a vascular lesion, lasting longer than 24 hours (if patient survives)
What is the pathogenesis causing a stroke?
Acute interruption of arterial supply to CNS = cerebral infarction (cell death), irreversible
List the components of the FAST acronym.
Facial drooping
Arm weakness
Slurred Speech
Take action - call 111
What is a transient ischaemic attack (TIA)?
Focal neurological deficit
Rapid onset - lasts mins to hours but less than 24 hours
Complete recovery
No evidence of infarction
Tend to recur - stroke after TIA more severe
Name the two mechanisms causing stroke.
Block - vessel is occluded
Bleed - vessel ruptures and bleeds into brain tissue
Both cause underperfusion of brain
Which is the most common type of stroke?
Ischaemia - 80%
What does an ischaemic stroke look like on a CT?
Isodense tissue = watery
List where a haemorrhagic stroke can occur.
Intracerebral
Subarachnoid
What other things can cause stroke?
Infection (with vasospasm)
Profound cerebral hypoperfusion = infarction (e.g. cardiac arrest)
List the two mechanisms causing an ischaemic stroke.
Thrombosis (2/3) and embolism (1/3)
Where does thrombosis causing ischaemic stroke occur?
Medium sized arteries
Atherosclerosis - usually in the presence of plaque rupture
Where does embolism causing stroke occur and what is a risk factor?
From site outside the brain - LA/LV/Carotid
AF is a risk factor
Thrombus moves elsewhere
What causes direct neuronal injury in a haemorrhagic stroke?
Decreased perfusion
Pressure effects (swelling)
Vasospasm –> adjacent ischaemia
Neurotoxicity
Why does a haemorrhagic stroke have higher early mortality?
Tends to have more global effects
Describe the signs and symptoms of a stroke.
Depends on the location of the lesion
Weakness if the most common sign
Usually UMN + localizing signs
What are the signs of a stroke in the anterior circulation?
Unilateral weakness Unilateral sensory loss Dysphasia Sensory inattention Visual field defect
NB: R stroke/L CVA
Stroke = SE of CVA CVA = cerebrovascular accident taking place in the brain
What are signs that a stroke occurred in the posterior circulation?
Unilateral weakness/sensory loss Cranial nerve signs Nausea and vomiting Inco-ordination Diplopia/disconjugate eyes
What are the major cortical signs?
Language impairment (dysphasia/aphasia)
- includes reading and writing
- mainly L cortex
- non fluent/expressive aphasia - broca’s area
- fluent/receptive aphasia - wernickes area - superior temporal lobe
Apraxia and Agnosia
- typically R parietal cortex
- Apraxia = inability to process, plan sequence motor takes
- Agnosia - inability to process sensory information - visual and sensory inattention
