10. Stroke Flashcards
what is stroke?
serious life threatening condition that occurs when the blood supply to part of the brain is cut off
what is TIA?
‘mini strokes’ which are clinically similar to strokes but completely resolve within 24 hours
what are the three types of stroke?
- ischaemic (85%) = thromboembolic
- haemorrhagic (10%) = intracerebral, subarachnoid
- other (15%) = dissection (separation of walls of artery), venous sinus thrombosis, hypoxic brain injury
what are the two main principles in managing a stroke?
are they in the window for thrombolysis (less than 4 hours)
do a CT scan to determine if it is a bleed (so then would not do thrombolysis)
which method of imaging is most preferentially used for stroke?
CT - ischaemia later on, a bleed will show up
MRI - ischaemia shows up as high signal area (not performed as much)
what are the clinical features of an anterior cerebral artery infarct?
- contralateral lower limb weakness and sensory loss (as AMA supplies medial areas of the motor and sensory homunculus)
- urinary incontinence (as the paracentral lobules of the cortex have excitatory and inhibitory effects on the M centre)
- apraxia and dysarthria due to frontal lobe damage
- split brain syndrome/alien hand (as corpus callosum affected)
what are the clinical features of a proximal middle cerebral artery infarct?
this affects all branches of the MCA:
- contralateral full hemiparesis (face, arm, and leg) - as the MCA supplies the internal capsule which carries fibres to the face, arm and leg even tho only face and arm area of motor homonculus= full paralysis
- contralateral sensory loss in upper limbs and face as lateral part of sensory homonculus affected
- contralateral homonymous hemianopia without macular sparing(destruction of superior and inferior optic radiations as they run through the temporal and parietal lobes
- aphasia (both areas affected if left hemisphere affected which is dominant)
- contralteral neglect (in left side if right parietal love affected which is more common)
what are some features associated with contralateral neglect?
not able to acknowledge the left side of space or body exists
tactile extinction - if touch each side simultaneously doesnt feel the affected side)
visual extinction
anosognosia - doesnt know they had a stroke due to left sided hemiparalysis and left sided neglect
what are the clinical features of an occluded lenticulostriate artery?
known as lacunar strokes causing destruction to small areas of internal capsule and basal ganglia but no cortical features
- pure motor (face, arm and leg equally as motor fibres travelling through internal capsule)
- pure sensory (face, arm and leg equally as sensory fibres travelling through internal capsule)
- sensorimotor (mixed caused by infarct as boundary between motor and sensory fibres)
what are the clinical features of distal MCA occlusion?
splits into superior and inferior divisions. superior supplies lateral frontal lobe (PMC, Broca’s) = contralteral face and arm weakness as lateral part of homonculous and expressive aphasia if left hemisphere affected
and inferior supplies lateral parietal lobe and superior temporal (PSC, wernicke’s and both optic radiations)= contralateral sensory changes in face and arm, receptive aphasia if left hemisphere, contralateral visual field defect without macular sparing (often homonymouss hemianopsia as both radiations damaged)
what are the clinical features of a posterior cerebral artery is occluded?
- contralateral homonymous hemianopia with macular sparing due to collateral supply from MCA
- contralateral sensory loss (as thalamus damaged which allows sensory pathways to enter to the internal capsule)
what are the symptoms associated with cerebellar infarcts?
nausea, vomit, headache, vertigo/dizziness
what are the clinical features of cerebellar infarcts?
ipsilateral signs = DANISH
possible ipsilateral brainstem signs as cerebellar arteries loop round to the cerebellum, and ipsilateral horners (as sympathetics run laterally through brainstem) and contralateral sensory loss (sensory pathways running laterally through brainstem)
what are the red flag symptoms of brainstem strokes?
contralateral limb weakness and ipsilateral cranial nerve signs = due to damage to CST (above decussation) and damage to cranial nerve nuclei on same side
what are the clinical features of distal basilar artery occlusion?
sometimes sudden death as supplies brainstem
- visual and oculomotor defects (as sends branches to midbrain where oculomotor nuclei are and can prevent blood flow to PCA which supplies occipital lobe)
- behavioural abnormalities
- somnolence, hallucinations and dream like behaviour(brainstem contain inmportant centres for sleep regulation)
- motor dysfunction often absent if cerebral puduncles can get blood from PCA
