10a.) Stroke Flashcards
Define a stroke
- A neurological deficit attributed to an acute focal injury of the central nervous system by a vascular cause, including cerebral infarction, intracerebral haemorrhage and subarachnoid haemorrhage
- “Serious life-threatening condition in which blood supply to part of brain is cut off. Signs & symptoms persist for more than 24 hours”
Define TIA (transient ischaemic attack)
- A transient episode of neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia without acute infarction
- “Mini stroke- similar features of a stroke but completely resolve within 24 hours”
State the 3 broad categories of stroke and for each include:
- Any subdivisions
- % of strokes that are this category
-
Ischaemic (85%)
- Thromboembolic
-
Haemorrhagic (10%)
- Intracerebral (rupture of vessel in brain parenchyma)
- Subarachnoid
-
Other (5%)
- Dissection (separation of walls of atery which can lead to blood accumulating in the separation and occluding the branches of the artery)
- Venous sinus thrombosis (occludes veins and causes backpressure & reduced blood flow resulting in ischaemia)
- Hypoxic brain injury
The emergency management of strokes is based on two main principles; state these two main principles
*NOTE: more stroke teaching later on in unit
- Are they in the window for thrombolysis? (<4hrs)
- Do a CT head to determine if it is a haemorrhagic or ischaemic stroke (as cannot give thrombolysis if it is a haemorrhagic stroke)
What imaging is preferred in suspected stroke, MRI or CT?
CT
Describe the appearance of an ischaemic stroke on CT
- Ischaemic area of brain not visible early on
- But as the infarct becomes more established ischaemic area will become more hypodense (darker)
Describe the appearance of a haemorrhagic stroke on a CT scan
- Bright white area, maybe with mass effect
Describe the appearance of ischaemia on an MRI
High signal area (bright)
What 2 things does the clinical features of a stroke depend on?
- Anterior or posterioc circulation (specifically if was ACA, MCA or PCA)
- Whether pathology is in the proximal or distal territory
Describe the classical presentation of someone who has had an anterior cerebral artery infarct
*7 points to disucss
-
Contralateral weakness in lower limb
- Homunculus and primary motor cortex
-
Lower limb affected much worse than face
- Homunculus
-
Contralateral sensory changes in same pattern as motor deficits
- Homunculus and primay somatosensory cortex
-
Urinary incontinence
- Paracentral lobules are essentially the most medial part of the motor/sensory cortices and supply the perineal area
-
Apraxia
- An inability to complete motor planning often caused by damage to left frontal lobe
-
Dysarthria/aphasia
- Unusual in ACA (in comparison to MCA infarcts where it is common) may be present if damage to frontal lobe
-
Split brain syndrome/alien hand syndrome
- ACA normally supplies corpus callosum hence may get damage to corpus callosum so hemispheres can’t communicate
![](https://s3.amazonaws.com/brainscape-prod/system/cm/302/452/938/a_image_thumb.png?1581663680)
MCA infarcts in the main trunk of the MCA have an 80% mortality associated with them; suggest why the mortality is so high for MCA infarcts
- MCA supplies large area of brain (lateral frontal & parietal lobes, superficial temporal lobes, lentiform nucleus, caudate nucleus, internal capsule)
- If the main trunk of MCA is affected large area of brain will be affected and hence there will be lots of cerebral oedema
Can haemorrhagic transformation occur in a stroke?
Yes, idea that is was initially an ischaemic stroke however the vessels in the infarcted area break down and it becomes a heamorrhagic stroke
The MCA can become occluded, and result in a stroke, in 3 places; state and describe the position of these 3 places
- Proximal (after where it branches/continues off the ICA and before the lenticulostriate arteries)
- Lenticulostriate artery/arteries
- Superior or inferior division
![](https://s3.amazonaws.com/brainscape-prod/system/cm/302/453/076/a_image_thumb.png?1581664133)
Describe the classical presentation of someone who has had a proximal MCA occlusion/stroke
All branches of MCA willbe affected:
-
Contralateral full hemiparesis (in which face, arm and leg are affected)
- Homunculus would make us think only face and arms affected however because MCA supplies internal capsule and the IC carries fibres to face, arm AND leg the leg is affected
-
Contralateral sensory loss in face and arm
- Most likely face and arm due to homunculus however if sensory fibres in IC capsule affected may be larger area
-
Visual field defects
- Destruction of both superior & inferior optic radiations which would lead to contralateral homonymous hemianopia without macular sparing. NOTE: more distal occlusions may only affect one radiation causing quandrantanopia
-
Aphasia
- Global if the dominant hemisphere affected (remember dominant hemisphere is usually left)- can’t understand or express words (Wernicke’s & Broca’s aphasia)
-
Contralateral neglect
- Usually occurs if lesion in right parietal lobe. Don’t acknowledge left side of space, or even own body, exists
Describe neglect, include:
- What is is
- Where lesion usually is
- Other features
- Don’t acknowledge left side of space or even own body exists despite visual fields being normal
- Lesion usually in right parietal lobe
- Other features:
- Tactile extinction: if touch either side simultaneously doesn’t feel the affected side
- Visual extinction: if ask to draw clock face will only put numbers on the right side
- Anosognosia: does not acknowledge that they have had a stroke so will confabulate (fabricate imaginary experinces) to explain disability