Stroke Flashcards
What is a stroke?
A cerebrovacular accident.
‘A series of life-threatening medical condition that occurs when the blood supply to the brain is cut off.’
What are the types of stroke?
Ischaemic - 85%
Thromboembolic
Haemorrhagic - 10-%
Intracerebral
Subarachnoid
Other - 5%
Dissection
Venous Sinus Thrombosis
Hypoxic brain injury (e.g. post cardiac arrest)
What do you do when have a stroke?
CT head - urgent
Thrombolysis window?
Bleed?
What do we hope to see in CT head?
In acute ischaemic stroke no finings on CT
Purpose of CT is to exclude haemorrhagic causes
If clear in acute setting (<4hours) can proceed with thrombolysis
What imaging could you see changes of a stroke in?
MRI
Describe the blood supply to the brain
From the ICA (anterior cerebral circulation)
From the vertebral arteries (posterior cerebral circulation)
Forming the circle of Willis
Terminal branches create 3 main arterial territories that load specific pathologies.
Describe the territories of the anterior, middle and posterior cerebral arteries
Anterior cerebral - front and middle
Middle cerebral - sides of the brain
Posterior cerebral - back of brain
Describe the symptoms of an anterior cerebral infarct
Unilateral contralateral weakness Similar distribution of sensory change Urinary incontinence Apraxia Dysarthria Corpus Callosum involvement - complex syndromes e.g. split brain syndrome, alien hand syndrome.
How can the consequences of a middle cerebral artery infarct vary depending on its location?
Trunk occlusion = 80% mortality as it supplies a very large area of the brain. There is also an increased risk of haemorrhagic transformation.
But, MCA can be divides into superior and inferior and it also gives off the lenticulostriate arteries. Therefore, if one of these was occluded, then the prognosis would depends on the part of the brain that became ischaemic.
What do you see if somebody has a middle cerebral artery infarct?
Contralateral hemiparesis - the remainder of the homunculus
Contralateral hemisensory loss
Hemianopia - usually homonymous
Aphasia
Hemispatial neglect - with non-dominant hemisphere infarction
Also:
Tactile extinction
Visual extinction
Anosognosia - “lack of insight”
Why is there often a full hemiparesis?
Proximal infarction with affects the MCA territory and the internal capsule through the leticulostriate arteries.
Distial infarction spares the internal capsule so only the area of the homunculus supplied by that branch will be affected.
What is the different between a proximal and a distal middle cerebral infarct?
Proximal occlusion infarct all of the tract causing a contralateral homonymous hemianopia.
Distal occlusion may only infarct part of the radiations leading to quadrantinopia.
When does globalaphasia occur?
Global aphasia can occur following a main trunk occlusion.
Otherwise, Broca’s and Wernicke’s areas are supplied by branches of the MCA.
What is Broca’s aphasia?
An expressive aphasia
Dominant frontal lobe
Reduced speech fluency with relatively preserved comprehension
Effort to initiate language which reduces to few disjointed words
Unable to construct sentences
‘Can’t get words out’
What is Wernicke’s aphasia?
Dominant temporo-parietal
Fluency intact but words muddled
Varies from few incorrect or non-existent word insertion to profuse outpouring of jargon.
Can be confused with psychosis
‘Word Salad’
