Flashcards in Week 202 - Stroke Deck (32)
What is the definition of a stroke?
A neurological deficit related to an atraumatic vascular event (within the brain)
Name the two main types of stroke and state which is more common by far
What does EDH stand for and what is it?
Extra-dural haematoma. It is not classed as a stroke as it forms outside of the outermost later of the meninges between the dura and the skull or spinal column
What does SAH stand for and where does it occur?
Subarachnoid haemorrhage > extracerebral / intracranial ruptured aneurysm, occurs between the pia mater and arachnoid layers of the meninges.
Briefly describe the structure of the cerebral arteries and Circle of Willis
From the internal carotid arteries branch the left and right middle cerebral arteries and the anterior cerebral arteries. Connecting the left and right anterior cerebral arteries is the anterior communicating artery. The posterior communicating arteries also branch off the ICA and link to the posterior cerebral arteries which arise from the single basilar artery formed by the joining of the two vertebral arteries
What are the 3 main clinical features of stroke?
1) focal clinical deficits
2) negative clinical phenomena (i.e. loss of function)
3) sudden onset
What are the principle risk factors for stroke?
Vascular ones largely:
- HTN - overweight - smoking - alcohol - diabetes
- little exercise - poor diet - age
Which areas of the brain (broadly) do the MCAs supply?
The lateral cerebral cortex and the anterior temporal lobes
Which areas of the brain do the ACAs supply?
The medial frontal lobe of the cerebral cortex and superior medial parietal lobes largely
Which area of the brain do the PCAs supply?
The posterior aspect of the brain - the occipital lobe
What clinical signs would exist with an anterior cerebral arterial stroke?
Contralateral UMN lower-limb motor weakness and sensory dysfunction. Behavioural abnormalities and aphasia may been seen if prefrontal cortex and supplemental motor areas are involved
Where is Broca's area (in the vast majority) and what is it involved with?
Left inferior frontal lobe (left frontal hemisphere); involved in the articulation of speech
If Broca's area is affected by stroke what is the resulting clinical feature?
Expressive Motor Dysphasia/Aphasia - difficulty with production of language and forming intelligible sentences though understand / comprehend others well. Stick to short sentences.
Where is Wernicke's area (in the vast majority) and what is it involved with?
Left superior posterior portion if the temporal lobe (left temporal hemisphere); involved in the comprehension of language.
If Wernicke's area is affected by stroke what is the resulting clinical feature?
Receptive (sensory) dysphasia / aphasia - difficulty with comprehension of others words and own words. Speech may be fluent but usually nonsensical
If a patient presents with left homonymous hemianopia where is the damage (infarct) most likely to be?
Right posterior cerebral artery territory > right occipital lobe
What is the most common type of/area for stroke?
Infarct; middle cerebral artery
If a patient presents with right-sided facial weakness (particularly lower face), right arm and leg weakness with sudden onset of severe headache, BP of 190/110 mmHg and HR 52 what is the likely cause?
Left-sided haemorrhagic stroke
(hints: right-sided limb weakness, sudden painful onset, Cushing reflex)
If a patient presents with signs of painful CNIII palsy what is a likely vascular cause?
An unruptured enlarging posterior communicating artery applying pressure to the oculomotor nerve
How might you differentiate a SAH from a migraine?
Both can be described as a "thunderclap headache" but it is likely that SAH will present with meningism (neck stiffness) and maximal headache experienced in a short space of time
Why do SAHs rarely present with focal signs?
They tend to spread quite widely, effecting several areas
Why is the middle meningeal artery vulnerable to rupture upon a blow to the side of the head?
It lies beneath the pterion, a fragile portion of the skull over the temple
What defines a TIA?
A neurovascular event with symptoms lasting <24hrs (in reality symptoms tend to be no longer than 20 mins)
What is CVST and how does it tend to differ from arterial stroke?
"Cerebral Venous Sinus Thrombosis" - essentially DVT of the brain. Evolves slowly, raised ICP, secondary bleeding, no respect for arterial territories, often occur in a very different demographic e.g. young
List some risk factors for CVST
hypercoagulability; pregnancy; combined pill; thrombotic disorders; dehydration; malignancy
In what way would management of a CVST generally differ from that of an ischaemic arterial stroke?
Anti-coagulate rather than treat with thrombolysis (though may occasionally thrombolyse)
With an infarction stroke what are the time restrictions imposed upon use of thrombolysis treatment?
Must be within 3hrs of onset (used in around 10% of all cases)
What investigation must be performed with all patients suspected of stroke?
CT head, early on
What is the most important thing to rule out with the use of CT in stroke?
Haemorrhage, as thrombolysis, anti-coagulation and ant-platelet contraindicated in haemorrhagic stroke
What is particularly advantageous about the use of MRI in suspected stroke?
Shows subtle defects early on (though is not routinely used in stroke investigation
Which areas of the brain are most susceptible to ischaemic injury?
Watershed zones, where arterial blood supplies meet