Stroke Flashcards
The brain receives blood from 2 sources.
Name them.
1- Anterior circulation
2-Posterior circulation
What is the anterior circulation fed by? and what area of the brain does it supply?
- Fed by the internal carotid arteries
- Supplies most of the cerebral hemispheres.
What is the posterior circulation fed by? and what area of the brain does it supply?
- Fed by the vertebral arteries
- Supplies the brainstem, cerebellum, some of the temporal lobe and occipital lobe.
What are the 2 main vessels of the anterior circulation.
1-Anterior cerebral artery
2-Middle cerebral artery
What is middle cerebral artery a direct continuation of?
Is a direct continuation of the internal carotid artery.
Coritcal branches of the middle cerebral artery emerge from where to supply where?
- Emerge from the lateral fissure
- Supply the lateral aspect of the cerebral hemisphere, including the lateral parts of the frontal and parietal lobes as well as the superior temporal lobe.
What are the deep branches of the middle cerebral artery known as?
The lenticulostriate arteries
What structures do the lenticulostriate arteries supply?
They supply the deep grey matter structures including the lentiform nucleus, caudate nucleus and the internal capsule.
What is the anterior cerebral artery a branch of?
The internal carotid artery.
The left and right anterior cerebral arteries anastomose in the mideline via what?
The anterior communicating artery
Cortical branches of the anterior cerebral artery supply what?
The medial aspect of the frontal and parietal lobes
The anterior cerebral artery sends cortical branches to supply the medial aspect of the cerebral hemisphere. But it also has deep branches.
What deep white matter structure does the anterior cerebral artery supply?
The corpus callosum
The posterior circulation is composed of what main vessels.
1- Basilar Artery
2-Vertebral arteries
What vessel forms the posterior cerebral arteries?
The bifurcation of the basilar artery forms the posterior cerebral arteries.
What aspect of the brain does the posterior cerebral artery supply?
The occipital lobe,and the inferior aspect of the temporal lobe.
The posterior cerebral artery also has branches supplying the midbrain and the thalamus.
True or false
True
What forms the basilar artery?
The confluence of vertebral arteries.
What does the superior cerebellar artery supply?
The superior aspect of the cerebellum and midbrain.
What do the pontine arteries supply?
The pons - specifically the corticospinal tract; therefore if blocked can destroy the corticospinal tract and result in locked in syndrome.
What does the anterior inferior cerebellar artery supply?
The antero-inferio aspect of the cerebellum and the lateral pons.
What does the posterior inferior cerebellar artery supply?
The postero-inferio aspect of the cerebellum and the lateral aspect of the medulla.
Lenticulostriate arteries are deep branches of the middle cerebral artery. They supply deep brain structures and easily blocked resulting in lacunar strokes.
Explain why lacunar strokes are so variable in their presentation?
Because the lenticulostriate arteries supply many deep brain structures such as the thalamus, basal ganglia and internal capsule.
So depending where the infarct has occurred and what structure is deprived of blood will depend on the presentation seen.
e.g. thalamus- pure sensory stroke
internal capsule-pure motor stroke
The spinal cord has 2 main blood supplies.
State them.
1-Anterior spinal artery
2-Posterior spinal arteries
What does the anterior spinal artery supply?
Supplies the anterior ⅔rd of the spinal cord, including the spinothalamic tract and the corticospinal tract.
What do the posterior spinal arteries supply?
Supplies the posterior ⅓rd of the spinal cord. Including the dorsal column pathway.
If the anterior spinal artery is blocked what would be see?
- Would most likely have a bilateral affect as the artery is located along the midline.
- Would see loss of spinothalamic modalities below level of the blockage.
- Would also see upper motor neurone signs below level of the blockage due to ischaemia of corticospinal tract.
If the posterior spinal arteries were blocked, what would we see?
- Unilateral loss
- Get ipsilateral loss of dorsal column modalities below level of the blockage.
Lable the circle of willis.
Define a stroke
A serious life threatening condition that occurs when the blood supply to part of the brain is cut off.
Define a TIA
A transient episdoe of neurological dysfunction caused by ischemia without acute infarction.
State 3 differentials for TIA?
1-Migraine
2-Electrolyte imbalances e.g. Hypoglycaemia
3-Vertigo
How would you invetsigate a TIA?
Bedside:
- History
- Clinical examination e.g. peripheral nerve exam, cranial nerve exam
- Lying & standing BP
- Full set of observations
Bloods:
-FBC
-CRP/ESR
-U&Es
-LFTs
-HbA1C
-Bone profile
-Creatine kinase
-LDL
-INR
Imaging:
-MRI
-ECG
What are the 2 main types of stroke and their prevalence?
1-Ischaemic stroke ( 85%)
2-Haemorrhagic stroke (15%)
What is an ischemic stroke?
Ischaemic strokes occur when the blood supply to an area of brain tissue is reduced, resulting in tissue hypoperfusion.
Suggest 3 causes of a ischaemia stroke?
1-Thrombosis (a blood clot forms locally within a cerebral vessel)
2-Embolism (an embolus originating somewhere else in the body)
3-Systemic hypoperfusion (blood supply to the entire brain is reduced secondary to systemic hypotension (e.g. cardiac arrest).
What is a haemorrhagic stroke?
Haemorrhagic strokes occur secondary to rupture of a blood vessel or abnormal vascular structure within the brain.
What are the 2 subtypes of haemorrhagic stroke?
1-Intracerebral haemorrhage (within the brain)
2-Subarachnoid haemorrhage (beneath the layer of the arachnoid mater)
Suggest 6 risk factors for a stroke
1-Excess alcohol
2-Smoking
3-Diabetes mellitus
4-Hypertension
5-Hyperlipidaemia
6-Heart disease
If someone is having a stroke its essential to first distinguish between an ischaemic and haemmorhagic stroke.
What type of scan can be used to do this?
CT Scan
A haemorrhagic stroke will be visable, a ischaemic stroke will be hard to see acutely, this helps to differentiate between stroke types.
If someone is having a ischaemic stroke how will they be managed acutely?
-Thrombolysis within 4.5 hrs ( alteplase to dissolve the clot)
or
-Thrombectomy (removal of the clot)
How is a haemorrhagic stroke managed?
Craniotomy to remove the bleed.
Why is somone with a haemorrhagic stroke not eligible for thrombolysis or thromectomy?
Because in this instance, the stroke is a result of bleeding in the brain. So the treatment of thromoblysis would only propogate the bleeding and worsen the stroke.
If it was ischaemic in orgin, the thrombolysis would dissolve the blood clot and help restore blood flow to the brain.
The anterior cerebral artery supplies what region of the brain?
The medial aspect of the frontal and parietal lobe, and the corpus callosum.
If there is an infarct at the anterior cerebral artery.
What problems would we see and why?
- Contralateral lower limb weakness (due blood supply of medial motor homunuclus being affected, medial homunuclus represents the lower limb)
- Contralateral lower limb sensory deficit ( due to medial area of sensory homunuclus being affected)
- Urinary incontinence ( if paracentral lobules are affected)
- ## Frontal lobe features ( personality change)
- Parietal lobe features ( apraxia)
- Split brain syndrome/ alien hand syndrome ( due to corpus callosum damage)
What is alien hand syndrome?
When hands work independently of one another
What artery is most commonly affected in stroke?
The middle cerebral artery
If there is an occlusion at the proximal aspect of the MCA. What problems would we see?
- Contralateral hemiparesis (weakness or the inability to move on one side of the body, initally flacid then spastic)
- Contralateral sensory deficit of lateral aspect of homunculus ( often soley face and arms)
- Contralateral homonymous hemianopia
What area of the brain does the middle cerebral artery supply?
The lateral aspects of the frontal, temporal and parietal lobes.
True or false.
The middel cerebral artery has further divisions, superior division, inferior division and lenticulostriate arteries.
True
If there is an occlusion at the proximal aspect of the MCA. What problems would we see?
All branches of the MCA are occluded including the lenticulostriate arteries. So we see;
- Contralateral hemiparesis of face, arm and leg (the UMNs travel via the internal capsule, which is supplied by lenticulostriate arteries, which are occluded)
- Contralateral sensory deficit of lateral aspect of homunculus ( often soley face and arms)
- Contralateral homonymous hemianopia ( optic radiations travel through parietal and temporal lobes)
-Global aphasia (Both brocas & wernickes) if stroke is on left side
If there is a left sided proximal MCA occlusion what additional signs might be seen?
Aphasia also seen due to Brocas and Wernickes area being affected
If there is a right sided proximal MCA occlusion, what else might we see?
Right sided occlusion affects right parietal lobe, reuslting in contralateral hemispatial neglect (pt. can’t acknowledge what is happening on the left hand side)
Lenticulostriate occlusions occur due to small emboli working their way up from the heart via the internal carotid artery, along the middle cerebral artery and into the lenticulostriate arteries where they lodge causing a lacuna stroke.
What symptoms are seen with a lacuna infarct?
-Lack cortical features such as aphasia or neglect because MCA blood supply to lateral aspect of the cortex is still intact.
The lenticulostriate arteries are affected and they supply the internal capsule. Therefore we get either;
1- Pure motor (face,arm,leg weakness-lacune in artery supplying motor region of internal capsule)
2-Pure sensory stroke (sensory change in face, arm, leg- lacune in artery supplying sensory region of internal capsule)
3-Sensorimotor stroke (mixture of motor and sensory symptoms- lacune in artery supplying sensory & motor region of internal capsule)
If there are no cortical features present in a MCA stroke. What do we know about the site of occlusion?
The lenticulostriate arteries are affected; a lacunar stroke.
Distal MCA occlusions can affect either the superior or inferior MCA .
True or false.
True
If there is a distal occluison of the MCA at the superior division.
What symptoms would we see?
-Superior division supplies the lateral frontal lobe.Therefore the occlusion causes;
- Contralateral face and arm weakness ( as frontal lobe (motor) affected and features are represented laterally)
- If left sided- get expressive aphasia due to Brocas area being affected ( located in frontal lobe)
If there is a distal occlusion of the inferior MCA what symptoms do we see?
- The inferior division supplies the lateral parietal and superior temporal lobe, therefore we see;
- Contralateral sensory chnage in face and arm ( as parietal lobe (sensory cortex) affected and features representated laterally)
- If left sided affected, we see fluent aphasia due to wernickes area being affected (located in superior temporal lobe)
- Contralateral homonymous hemianopia ( as both optic radiations affected)
If there was an occlusion of all the MCA branches. As demonstrated in the image. What symptoms would we see?
The sum of both the superior and inferior division occlusions.
What area of the brain does the posterior cerebral artery supply?
Supplies posterior medial aspect of parietal lobe and temporal lobe and the occipital lobe
What problems are seen with a posterior cerebral artery infarction?
- Contralateral homonymous hemianopia WITH macula sparing ( due to dual blood supply from MCA)
- Contralateral sensory loss (due to thalamic involvment )
Name the 3 arteries which supply the cerebellum.
1-Superior cerebellar artery
2-Anterior inferior cerebellar artery
3-Posterior inferior cerebellar artery
Occlusions of the superior and inferior cerebellar artery can also occur. With reference to the DANISH acronym, state some signs/smptoms.
-Dysdiadochokinesis
-Ataxia
-Nystagmus
-Intention tremor
-Scanning dysarthria
-Hypotinia
Are cerebellar signs resultant from cerebellar artery occlusions contralateral or ipsilateral?
Ipsilateral
Why are there also possible ipsilateral cranial nerve signs and contralateral sensory deficits with cerebellar strokes?
Because the cerebellar arteries also supply the brain stem which is the site of cranial nerve origin and the site in which sensory pathways run through.
What areas of the brain do basilar arteries supply?
Brainstem & cerebellum
If there is an occlusion in the basilar artery what syndrome can result?
Locked in syndrome ( if pontine arteries are blocked too)
The body is paralysed but have preservation of oculomotor nerve so eye movements are spared.
What system can be used to classify ischaemic stroke?
Bamford classification system
Nb-(also known as the Oxford classification system).
Name the 4 different types of stroke identified by the Bamford/Oxford stroke classification?
1-Total anterior circulation stroke (TACS)
2-Partial anterior circulation stroke (PACS)
3-Lacunar syndrome (LACS)
4- Posterior circulation syndrome (POCS)
What is the criteria for a total anterior circulation stroke (TACS)?
All 3 of the following:
1-Unilateral weakness of the face, arm & leg.
2-Homonymous hemianopia
3-Higher cerebal dsyfunction
What is the criteria for a partial anterior circulation stroke (PACS)?
Two of the following:
1-Unilateral weakness of the face, arm & leg.
2-Homonymous hemianopia
3-Higher cerebral dysfunction
What is the criteria for a LACS?
One of the follwoing:
- Pure sensory stroke
- Pure motor storke
- Sensori-motor stroke
- Ataxic hemiparesis
What is the criterai for a POCS?
One of the follwing:
1-Cranial nerve palsy and a contralateral motor/sensory deficit
2-Bilateral motor/senosry deficit
3-Conjugate eye movement disorder
4-Cerebellar dysfunction
4-Isolated homonymous hemianopia or cortical blindness
