Case 5 - Stroke Summary Flashcards
what is stroke diagnosis confirmed with
imaging
what is a TIA
essentially a minor stroke. it may present with stroke Like symptoms but the clinical effects will completely resolve within 24 hours. they are usually the result of micro-emboli. sometimes a mass lesion may mimic a TIA and other tines, they are the result of a temporary reduced blood flow e.g with massive postal hypotension, or decreased blood flow through a stenosed artery.- which is later compensated for by auto regulation mechanisms
what is a completed stroke
when the clinical effects have reached their maximum - usually with in six hours of the onset
what is stroke in evolution
describes the progress of a stroke in the first 24 hours
what are presentation has a poor prognosis
drowsiness
when will damage occur
when the blood flow to the brain tissue drops below 50%
why do most strokes occur in the morning
the blood pressure is lowered during the night whilst asleep, but on waking, the BP increases an is now more likely to dislodge any embolism
low doses of aspirin effect on stroke
has no proven beneficial effect, and in fact, high usage of COX-2 inhibitors increases the risk. it is now also though the at low dose oestrogen does not significantly increase the risk in otherwise healthy women
what is a rare, inherited cause of stroke and vascular dementia
CADASIL
what is CADASIL caused by
defective NOTCH3 gene. there are many small infarcts in the brain. often presents as migraine and depression in teenage
what are most TIAs due to
80% due to thromboembolism
signs based on region of the brain:
what is amaurosis fugax
this is a sudden loss of vision in one eye, caused by an infarct in the retinal arteries. you can sometimes see the obstruction on ophalmoscopty, which is useful clinically, as the same symptoms are seen in migraines, where the arteries will always appear normal. thus if s defect is visible, it is highly likely to be the result of TIA
what is transient global amnesia
this involves an episode of amnesia that usually occurs in those over 65, and completely resolves within 24 hours. unlikely to happen more than once in the same patient
what suggests subclavian artery stenosis
difference of more than 20mmHg between arms
what is the prognosis for a TIA
5 years after a TIA;
- 30% of patients have a stroke
- 15% have an MI
where is a TIA the most serious
in the anterior circulation than a TIA in the posterior circulation
what is the management of a patient with suspected TIA
they are often admitted based on their ABCD2 score. this score predicts the likelihood of a further CVA event a patient with a score greater than 4 should be admitted and 3 or less should be investigated as an outpatient
what is the big follow up investigation
a carotid doppler scan - to check the levee of carotid artery stenos.
what risk level requires a carotid endarterectomy
60%
what is the immediate management
300mg of aspirin should be given once diagnosis is confirmed, usually after CT confirms there is no haemorrhage stroke
what dose of aspirin do you continue with after the initial 300 mg
100mg daily
what is the biggest cause of cerebral infarct
atherosclerosis of the carotid Arteries and the aortic arch - 60%
what is the most common stroke presentation
branch of the middle cerebral artery
what does an infract to the MCA affect
the internal capsule. a similar set of signs will be caused by internal carotid occlusion
in these cases there is what:
hemiparesis
Hemiplegia
Limbs usually floppy, and reflexes reduced or absent
Facial weakness
Hemianopia - visual field defect in which vision is lost in half of the visual field in one or both eyes
Aphasia - when the dominant hemisphere is affected
Important to ask about right and left handedness
These symptoms usually develop rapidly, over a period of minutes or less commonly they can develop over a free years
are there any headaches with a MCA occlusion
not usually - there are no pain receptors within the brain itself
what happens to reflex after stroke
will return early on, but often become exaggerated with an extensor plantar response
if there is a headache, impaired consciousness then the cause is likely to involve what
some sort of swellings and thus if the onset it acute, it is likely to be haemorrhage
what to look for in eye examination
diabetic changes
retinal emboli
hypertensive changes
arcus snellis
what is arcus snellis
a grey or white arc visible above or below the cornea
sudden cessation of blood supply to neurones leads quickly to hypo cells. what does this cause?
- the Na+K+ pump fails and Na begins to accumulate in the cell
this excess Na changes the osmotic balance, and more liquid enters the cell causing oedema
what happens due to this oedema
the oedema is highly significant. in the direct area around the infarct, the cells will die very quickly, as they swell and burst. but in the area around this there are cells that have oedema but can be saved. this is the penumbra
what happens as these cells swell and b burst
there is an increase in intracranial pressure which can further affect the bloody supply to the area, resulting in a vicious circle.
what is another factor in the accumulation of Na _
the continued depolarisation of neurones in the affected area. this is because the re uptake process for glutamate is dependent on ATP an without O2 there is not ATP, so glucose remains present in the synaptic regions, and cells remain depolarised
the mechanism of cell damage, as a result of prolonged depolarisation of the cell is known as what
excitotoxicity
what can excitotoxicity also result in
the failure of the AMPA and NMDA receptors, which allows excessive levels of calcium into the cell
what does the high level of calcium in a cell allow for:
- the release of free radicals - which also leads to necrosis in the area
- the production of cytokines which causes inflammation
- Ca2+ can also directly lead to apoptosis in the penumbra
examples of clinical features in a brain stem infarct
what are the several names that all mean the same thing for brainstem stroke patterns
Wallenberg syndrome
lateral medullary syndrome
posterior inferior cerebellar artery thrombosis (PICA)
what are the contralateral signs of these syndrome
- spinothalamic sensory loss
- hemiparesis
what are the ipsilateral signs of these syndromes
- facial numbness (V)
- diplopia (VI)
- nystagmus
- ataxia
- Horner’s syndrome
- 9th and 10 th nerve lesions
what is Horner’s syndrome
characterized by a constricted pupil (miosis), drooping of the upper eyelid (ptosis), absence of sweating of the face (anhidrosis), and sinking of the eyeball into the bony cavity that protects the eye (enophthalmos).
why would coma be an outcome of a stroke
from a stroke affecting the reticular activating system
what is locked in syndrome caused by
an upper brainstem infarct
what is pseudo bulbar palsy and what is it the result of
result of a lower brainstem infarct. results in bilateral impairment of 9-12th cranial nerves. there is dysarthria and dysphagia
what is a lacunar infarct
infarcts in the Deep arteries of the brain. they can be seen on MRI and often are symptomless
what is hypertensive encephalopathy
literally means damage to the brain. in this case, as a result of malignant hypertension
what is papilloedma due to
direct infarct affecting the optic nerve
infarct in other part of brain, causing oedema and therefore puts pressure on the optic disc
what Is Weber’s syndrome
the result of an infarct on one side of the midbrain
what does Weber’s syndrome present with
ipsilateral III nerve paralysis
contralateral hemiplegia
what are diffusion MRI scans
these detect abnormalities much earlier than on normal MRI and ct
this type of MRI exploits the fact that damaged cells fill with water and thus contain more water than normal cells in early stages of damage
what is an angiography
an MR that looks at the blood bezels in the head and neck.
how to disinguish between the blood vessels on a MRA
vertebral artery is often the smallest
the internal carotid has no branches
external carotid has branches
what does an MR angiography show
areas of stenosis and thrombus formations. it is also useful when looking for aneurysms
what are haemorrhages almost always the result of
uncontrolled chronic hypertension
what are some contra-indications for thrombolysis
- major surgery, trauma less than two weeks ago
- active internal bleed
- prolonged or traumatic CPR
- pregnancy
- severe liver disease
- hypertension >200/120
- cerebral neoplasm
what is the treatment plan for aspirin
300mg daily for 2 weeks and then 75mg per day
what is given if aspirin hypertensive,
give clopidogrel
what should also be given is ischaemia is confirmed by CT or MRI
dipyridamole
