Lecture 16 — Stroke Flashcards
What is the Definiton of a stroke?
A serious life threatening condition that occurs when the blood supply to part of the brain is cut off with signs and symptoms persisting for longer than 24hrs
What is a transient ischaemic attack (TIA)?
The same clinical features of a stroke but resolves within 24hrs (essentially a stroke resolving in 24hrs)
What are the main types of stroke?
Ischaemic stroke (thromboembolism)
Haemorrhagic (rupture of blood vessels)
Arterial dissection
Venous sinus. Thrombosis
Hypoxic brain injury
What occurs in an ischaemic stroke?
Occlusion of a blood vessel usually due to the rupture of an atherosclerotic plaque
What are the main types of Haemorrhagic stroke?
Subarachnoid haemorrhage
Intracerebral haemorrhage (blood vessel in the brain)
How does venous sinus thrombosis lead to a stroke occurring?
Impairs the venous drainage (back pressure) which impairs arterial blood flow to the brain leading to ischaemia
What is the emergency management of stroke?
Do CT head to determine if its a bleed
Give thrombolysis if less than 4hrs since stroke and stroke cause is not a bleed
How does blood appear on a CT head?
White
How does blood appear on an MRI?
High signal area
Slide 6:
What type of haemorrhage is seen on the right CT?
Describe it:
Subarachnoid haemorrhage
Blood has filled the basal cisterns producing. A 5 pointed star pattern
How does an acute ischaemic stroke appear on CT?
Likely no changes however you may see a hyper dense area indicating a thrombus
Slide 7:
What is visible on the left CT?
Hyper dense Middle cerebral artery indicating a thrombus in this area
What type of imaging is very good at identifying ischaemic stroke?
How does it appear?
MIR
High signal area (whiter area)
How may a head CT change as a stroke evolves?
Can look normal but then weeks area have darker areas indicating neuronal damage and oedema
What makes up the anterior brain circulation?
Anterior and middle cerebral arteries
What arteries feed the anterior circulation of the brain?
Internal carotid arteries
What arteries supply the posterior circulation of the brain?
Vertebral arteries
Go to slide 9 and complete the blood supply to the brain:
What part of the brain does the Anterior Cerebral Artery supply? (ACA)
Medial aspect of frontal and parietal lobes (motor and sensory homunculus)
Corpus callosum
What part of the brain do the Middle Cerebral Arteries supply?
Lateral aspect of frontal and parietal lobes (motor and sensory homunculus)
Lateral aspect of Superior temporal lobe
Deep structures like internal capsule, lentiform nucleus and caudate
What branch from the middle cerebral artery supply the internal capsule?
Lenticulostriate arteries
What part of the brain do the posterior cerebral arteries supply?
Occipital lobe
Inferior temporal lobe
Thalamus
What is the most commonly affected artery in stroke?
Middle cerebral artery
How does an Anterior Cerebral artery infarction present in a patient?
Think about the areas which the anterior cerebral artery supplies
Contralateral lower limb weakness
Contralateral lower limb sensory change
Urinary incontinence
Apraxia
Dysarthria/aphasia (rare)
Split brain syndrome (rare)
Why does an Anterior Cerebral artery infarct cause Contralateral lower limb weakness and sensory change?
ACA supplies medial aspect of frontal and parietal lobes which include the medial aspect of primary sensory and motor cortex which supplies the lower limb
Why does an anterior cerebral artery infarct cause urinary incontinence?
The paracentral lobules which are responsible for supplying the external urinary sphincter are represented medially in the brain
Why can an Anterior Cerebral artery infarct cause Split brain syndrome or alien hand syndrome?
Branch of the ACA supplies the corpus callosum which is a white matter tract allowing communication between the 2 hemispheres
What is Apraxia?
Difficulty doing every day tasks (motor planing)
Why can an Anterior Cerebral artery infarction cause apraxia?
Damage to the left frontal lobe due to the ACA supplying this part of the medial frontal lobe
Go to slide 11 and label the arteries:
What parts of the brain do the lenticulostriate arteries supply?
Entire internal capsule
+
Basal ganglia (includes lentiform nucleus, caudate)
With middle cerebral artery infarcts, what is worse, the infarction being more proximal or distal?
Proximal
Since the more proximal, the worse the damage to the brain so the more oedema that occurs and the higher the ICP becomes
Slide 12:
Label the Middle Cerebral Artery
How does a main stem Middle Cerebral Artery occlusion/infarction present?
Think about the areas it supplies
Contralateral hemiparesis of face arm and leg
Contralateral sensory loss
Contralateral homonymous hemianopia
Global aphasia if left sided
Left sided neglect if right sided
What do the cortical branches supply from the middle cerebral artery?
Lateral aspect of parietal lobe and superior temporal lobe
What are the cortical branches of the middle cerebral artery?
Superior division
Inferior division
What does the superior cortical divison of the middle cerebral artery supply?
Lateral aspect of frontal lobe
What does the inferior cortical divison of the middle cerebral artery supply?
Lateral parietal lobe
Superior aspect of temporal lobe
Why with a main stem Middle Cerebral Artery occlusion/infarct do you get contralateral hemiparesis of face, arm and leg?
MCA gives of Lenticulostriate arteries which supply the internal capsule + basal ganglia
The Lenticulostriate arteries contain UMN so UMN are unable to reach the spinal cord due to internal capsule damage
Why with a main stem Middle Cerebral Artery occlusion/infarct do you get contralateral sensory loss?
The Lenticulostriate arteries supply the internal capsule and basal ganglia
Internal capsule as well as containing UMN also contain ascending sensory fibres
Why with a main stem Middle Cerebral Artery occlusion/infarct do you get contralateral homonymous hemianopia?
The white matter of the parietal and temporal lobe contains optic radiations (parietal = superior optic radiations) and (temporal = inferior optic radiations)
Why with a main stem Middle Cerebral Artery occlusion/infarct do you get global aphasia if it’s left sided?
Left cerebral hemisphere is responsible for speech
Brocas area is in the inferior lateral frontal lobe
Wernickes area is in the superior temporal lobe
These areas are supplied by the Middle Cerebral Artery
What is neglect?
The failure to acknowledge the existence of usually the left side of space, left side of objects or left side of own body
What part of the brain is normally damaged with neglect?
Right parietal lobe
What signs are seen in neglect?
Tactile extinction (will only acknowledge touch on right side when touched on both left and right side simultaneously)
Visual extinction (wave 2 hands will only acknowledge the hand on the right side)
Anosognosia
What is anosognosia seen in neglect?
Patient doesn’t acknowledge theres a problem
They’ll say they just dont want to move their arm even though it’s paralysed
How do lacunar infarcts (branch of MCA) present?
Lack cortical features like aphasia or neglect
Equally effects sensory and motor function of Face arms and legs
What leads to a pure motor stroke affecting the face arms and legs equally in a lacunar infarct?
The infarct affects the internal capsule more anteriorly
What leads to a pure sensory stroke affecting the face arms and legs equally in a lacunar infarct?
The infarct affects the internal capsule more posteriorly
What leads to a sensorimotor stroke affecting the face arms and legs equally in a lacunar infarct?
Mixture of both UMN and ascending sensory nerves in the internal capsule more in the middle
With a main stem middle cerebral artery occlusion/infarct, does the Contralateral homonymous hemianopia have macular sparing?
No macular sparing
How does a patient with a Middle Cerebral Artery occlusion at the inferior division present?
Contralateral sensory change in face and arm
Wernickes/receptive aphasia if left sided
Contralateral homonymous hemianopia
Why does a patient get Contralateral sensory change in the face and arm with a Middle Cerebral Artery occlusion at the inferior division?
Since lateral parietal lobe supplied by this and this is the part of the sensory homunculus for the face and arms
Why does a patient get Wernickes/receptive aphasia with a Middle Cerebral Artery occlusion at the inferior division if it’s on the left side?
Wernickes area is in the superior temporal lobe which is supplied by the inferior division of the MCA
Why does a patient get Contralateral homonymous hemianopia with a Middle Cerebral Artery occlusion at the inferior division?
Both superior and inferior optic radiations in the parietal and superior temporal lobe respectively are destroyed
How does a patient with an occlusion//infarction in the superior division of the middle cerebral artery present?
Contralateral face and arm weakness
Brocas/expressivee aphasia if left sided
Why does a patient get Contralateral motor change/weakness in the face and arm with a Middle Cerebral Artery occlusion at the superior division?
Lateral frontal lobe supplied by this and this is where the face and arm are represented on the motor homunculus
Why does a patient get Brocas/expressive aphasia with a Middle Cerebral Artery occlusion at the superior division if it’s left sided?
Broca’s area located in the inferior lateral frontal lobe
How does a patient present if you get occlusion of all the cortical branches of the middle cerebral artery?
Just the same affects of the superior + inferior division occlusion
Contralateral sensory and motor weakness in face and arm
Wernickes + Brocas aphasia = global aphasia if its left sided
Contralateral homonymous hemianopia without macular sparing
How does a patient with a Posterior Cerebral Artery occlusion/infarction present?
Contralateral homonymous hemianopia with macular sparing
Complete Contralateral sensory loss or change
Why do patients with a posterior cerebral artery occlusion/infacrtion have contralateral homonymous hemianopia with macular sparing?
Supplies occipital lobe
Macule sparing since has dual blood supply from the Middle Cerebral Artery (MCA))
Why do patients with a posterior cerebral artery occlusion/infacrtion have contralateral sensory loss?
Posterior Cerebral Artery (PCA) supplies the thalamus via thalamoperforator/thalamogeniculate branches
So if PCA blocked thalamus not receiving blood supply and its essential in both sensory tracts
How do the Contralateral homonymous hemianopias occurring with MCA and PCA occlusions differ?
PCA occlusion = macular sparring since collateral supply from MCA
MCA occlusion = NON macular sparring
How do patients with brainstem strokes present?
Crossed deficit:
-Ipsilateral cranial nerve deficits (brainstem signs)
-contralateral sensory and motor signs (above decusstion of pyramids)
What are the symptoms of a cerebellar stroke?
Nausea
Vomiting
Vertigo/dizziness
Headache
What are the sings of a cerebellar stroke?
Ipsilateral cerebellar signs (DANISH)
Ipsilateral cranial nerve signs
Possible Contralateral sensory deficient
Possible Ipsilateral HORNERS syndrome
What are the Ipsilateral cerebellar signs?
Dysdiadochokinesia
Ataxia
Nystagmus
Intention tremor
Slurred speech
Hypotonia
How does a patient present if they have an occlusion in the distal/superior portion of the basilar artery (tip of the basilar)?
Visual and oculomotor deficits
Behavioural abnormalities
Somnolence, hallucinations and dreamlike behaviour
Why can some visual deficits be rescued in a tip of basilar artery occlusion?
Occipital lobes also supplied by the posterior communicating artery
Why is motor dysfunction usually absents in tip of basilar artery occlusion?
Cerebral peduncles reduced by posterior communicating artery
Why can you get dreamlike behaviour in tip of basilar artery occlusion?
Basilar normally gives of branches that go to the reticular formation that controls sleep in teh mid brain
How does a patient present with a full width occlusion of the proximal basilar artery that’s over the pontine artery branches ?
LOCKED IN SYNDROME (can still move eyes)
Why does locked in syndrome occur with a basilar artery occlusion over the pontine branches?
Why can the eyes still be moved?
Pontine arteries supply the corticospinal tracts of the body, occlusion = full body paralysis
Eyes can still be moved because the midbrain is still being supplied by the Posterior Cerebral arteris
Still conscious since midbrain’s reticular formation still in tact
What system do we use to classify strokes?
Bamford/oxford stroke classification
