Stroke Flashcards
What are the two types of cerebrovascular accident?
Ischaemia or infarction of the brain tissue secondary to inadequate blood supply
Intracranial haemorrhage
What can cause disruption of the blood supply leading to a stroke or TIA?
Thrombus formation or embolus, for example in a pt with AF
Atherosclerosis
Shock
Vasculitis
What is a TIA?
Transient ischemic attack is transient neurological dysfunction secondar to ischemia without infarction (previously definied as symptoms of a stroke resolving within 24hrs)
They often precede a full stroke
What is a cresendo TIA?
A crescendo TIA is where there are two or more TIAs within a week. This carries a high risk of developing in to a stroke.
Presenting features of a stroke?
Sudden weakness of limbs
Sudden facial weakness
Sudden onset dysphasia (speech disturbance)
Sudden onset visual or sensory loss
Stroke risk factors?
Cardiovascular disease such as angina, myocardial infarction and peripheral vascular disease
Previous stroke or TIA
Atrial fibrillation
Carotid artery disease
Hypertension
Diabetes
Smoking
Vasculitis
Thrombophilia
Combined contraceptive pill
What tool is used in A&E to identify stroke and what score indicates stroke is likely
ROSIER anything above 0
Mgx stroke
Admit patients to a specialist stroke centre
Exclude hypoglycaemia
Immediate CT brain to exclude primary intracerebral haemorrhage
Aspirin 300mg stat (after the CT) and continued for 2 weeks
Once intracranial haemorrhage excluded thrombolysis or thrombectomy
What is used in stroke management for thrombylsis?
Alteplase (a tissue plasminogen activator that rapidly breaks down clots)
When should alteplase be given by to reverse the effects of a stroke?
Within 4.5 hours
What is thrombectomy?
Mechanical clot removal, which may be offered within 24 hours of the honest of symptoms (depending on the location) if an occlusion is confirmed on imaging
Why should blood pressure not be lowered during a stroke?
Risk of reduced perfusion to the brain
TIA management
Start aspirin 300mg daily.
Start secondary prevention measures for cardiovascular disease.
They should be referred and seen within 24 hours by a stroke specialist.
What is used as secondary stroke prevention
Clopidogrel 75mg OD
Atorvastatin 80mg should be started but no immediatley
Carotid endarterectomy or stenting in patients with carotid artery disease
Treat modifiable risk factors such as hypertension and diabetes
What specialist imaging can be used to establish the vascular territory involved in a stroke?
Diffusion weighted MRI/CT
Carotid ultrasound can be used to assess for carotid stenosis
What is the gold standard stroke imaging?
Diffusion weighted MRI
Once patients have had a stroke they require a period of adjustment and rehabilitation. This is essential and central to stroke care. Who is involved as part of the MDT?
Nurses
Speech and language (SALT)
Dieticians
Physiotherapy
Occupational therapy
Social services
Optometry and ophthalmology
Psychology
Orthotics
How does an infarct appear on CT head?
Hypodense
How does cerebellar dysfunction present?
DANISH:
Dysdiadochokinesia (an inability to perform rapid alternating hand movements)
Ataxia (a broad-based, unsteady gait)
Nystagmus (involuntary eye movements)
Intention tremor (seen when the patient is asked to perform the ‘finger-nose test’)
Slurred speech
Hypotonia
Causes of cerebellar dysfunction?
Most common: Stroke (ischemic more commonly than haemorrhagic, affecting the POSTERIOR CIRCULATION), multiple sclerosis
Other: Lyme disease, trauma to posterior fossa, alcoholism, drugs such as phenytoin or carbamazepine, primary tumors (e.g. cerebellopontine anfle tumours, acoustic neuroma), metastases - e.g. breast cancer, lunge cancer, congenital causes such as Friedrich’s ataxia, and the spinocerebellar ataxias.
What does dysphagia suggest about the nature of a stroke?
Dominant cortex involvement
Most common type of ischemic stroke?
Middle cerebral artery territory infarcts are the most common of the thromboembolic strokes.
The presence of isolated monoparesis (pure motor stroke) suggests what classification?
Lucanr strokes (LACS)
TACS
A total anterior circulation stroke (TACS) is a large cortical stroke affecting the areas of the brain supplied by both the middle and anterior cerebral arteries.
All three of the following need to be present for a diagnosis of a TACS:
Unilateral weakness (and/or sensory deficit) of the face, arm and leg
Homonymous hemianopia
Higher cerebral dysfunction (dysphasia, visuospatial disorder)
PACS
A partial anterior circulation stroke (PACS) is a less severe form of TACS, in which only part of the anterior circulation has been compromised.
Two of the following need to be present for a diagnosis of a PACS:
Unilateral weakness (and/or sensory deficit) of the face, arm and leg
Homonymous hemianopia
Higher cerebral dysfunction (dysphasia, visuospatial disorder)*
*Higher cerebral dysfunction alone is also classified as PACS.
POCS
A posterior circulation syndrome (POCS) involves damage to the area of the brain supplied by the posterior circulation (e.g. cerebellum and brainstem).
One of the following need to be present for a diagnosis of a POCS:
Cranial nerve palsy and a contralateral motor/sensory deficit
Bilateral motor/sensory deficit
Conjugate eye movement disorder (e.g. horizontal gaze palsy)
Cerebellar dysfunction (e.g. vertigo, nystagmus, ataxia)
Isolated homonymous hemianopia
LACS
A lacunar stroke (LACS) is a subcortical stroke that occurs secondary to small vessel disease. There is no loss of higher cerebral functions (e.g. dysphasia).
One of the following needs to be present for a diagnosis of a LACS:
Pure sensory stroke
Pure motor stroke
Sensori-motor stroke
Ataxic hemiparesis
What does the ACA supply
The anterior cerebral arteries supply the anteromedial area of the cerebrum.
What does the MCA supply
The middle cerebral arteries supply the majority of the lateral cerebrum.
What does the PCA supply
The posterior cerebral arteries supply a mixture of the medial and lateral areas of the posterior cerebrum.
What is CPP
Cerebral perfusion pressure (CPP) drives oxygen and nutrient supply to brain tissues.
The brain can autoregulate blood flow in order to ensure constant flow that is isolated from fluctuations in systemic blood pressure.
This microcirculation is regulated by cerebral vessel constriction and dilatation.
Most of the blood within the cranial cavity is contained within the low-pressure venous system. Venous compression is the main method of displacing blood volume in the aforementioned mechanism.
This is the mechanism that is frequently lost secondary to head trauma, leading to cerebral ischaemia and neuronal death (secondary brain injury). CPP can be calculated using the following formula
CPP = MAP – ICP
From which arteries is the anterior circulation of the brain derived?
Internal carotid artery, left and right
From which arteries is the posterior circulation of the brain dervived?
Left and right vertebral arteries
What is the anterior circulation of the brain responsible for supplying?
Cerebrum
Opthalmic artery
ICA - course and branches
The left and right common carotid arteries bifurcate at the level of C3/C4 to give off the internal carotid arteries (ICA) within the carotid sheath.
The internal carotid arteries then proceed through the respective carotid canal, within the petrous portion of the temporal bone.
Once in the cranial cavity, the internal carotid arteries pass anteriorly through the cavernous sinus.
Once the internal carotid arteries are distal to the cavernous sinus, each gives rise to the following branches:
Ophthalmic artery: Supplies all the structures in the orbit as well as some structures in the nose, face and meninges.
Posterior communicating artery:
Anteriorly connects to the internal carotid artery prior to the terminal bifurcation of the ICA into the anterior cerebral artery and middle cerebral artery.
Posteriorly, it communicates with the posterior cerebral artery.
Anterior cerebral artery: Supplies oxygenated blood to most midline portions of the frontal lobes and superior medial parietal lobes.
The internal carotid arteries then continue as the middle cerebral arteries. The middle cerebral arteries supply the lateral cerebral cortex, in addition to the anterior temporal lobes and the insular cortices.
The left and right common carotid arteries bifurcate at what level to give off the internal carotid arteries (ICA) within the carotid sheath?
C3/C4
ICA segments
C1 – Cervical
C2 – Petrous
C3 – Lacerum
C4 – Cavernous
C5 – Clinoid
C6 – Ophthalmic (supraclinoid)
C7 – Communicating (terminal)
What is the posterior circulation responsible for supplying?
Occipital lobes
Cerebellum
Brainstem
Vertebral arteries - course and branches
The left and right vertebral arteries arise from their respective subclavian arteries, on the posterosuperior aspect.
The vertebral arteries then proceed to enter the transverse foramina of the spine at level C6 and continue superiorly.
After passing through the transverse foramen of C1, the arteries traverse the foramen magnum.
Once inside the cranial vault, the vertebral arteries give off the following branches:
Posterior inferior cerebellar artery (PICA) – this is the largest branch of the vertebral artery and is one of three main arteries supplying the cerebellum
Anterior and posterior meningeal arteries – supply the dura mater
Anterior and posterior spinal arteries – supply the spinal cord along its entire length
The vertebral arteries then converge to form the basilar artery at the base of the pons, inside the cranium.
Segments of the vertebral artery
V1 – preforaminal
V2 – foraminal
V3 – atlantic, extradural, or extraspinal
V4 – intradural, intracranial
Basilar artery: course and branches
The basilar artery runs superiorly within the central groove of the pons, giving off a number of branches including the pontine arteries, which supply the pons.
The basilar artery eventually anastomoses with the circle of Willis via the posterior cerebral arteries and posterior communicating arteries.
Locked in syndrome
Pontine infarcts cause an interruption in the myriad of neuronal pathways enabling communication between the cerebrum, cerebellum and spinal cord. This can result in complete paralysis of all voluntary muscle groups, sparing those controlling the eyes. Individuals suffering from damage to the pons are fully conscious and cognitively intact.
Circle of Willis
the terminal branches of the anterior and posterior circulation form an anastomosis to create a ring-like vascular structure known as the circle of Willis, within the base of the cranium (highlighted in pink below).
The left and right internal carotid arteries continue as the middle cerebral arteries (MCA), after each giving off a branch to supply the anterior cerebral arteries (ACA). The anterior communicating artery links the two anterior cerebral arteries together.
The internal carotid arteries also give off the posterior communicating arteries (PCoA), linking the middle cerebral arteries (MCA) with the posterior cerebral arteries
Berry aneurysms in the circle of Willis are a common cause of non-traumatic subarachnoid hemorrhage - how are they managed?
An anyeurysm where is associated with CN3 nerve palsy?
The third cranial nerve is commonly affected by aneurysms in the circle of Willis, particularly those involving the posterior communicating artery (PoCA) due to its close anatomical relationship.
CN3 palsy - medical vs surgical?
Clinically, “surgical” third nerve palsy can be differentiated from “medical” third nerve palsy by evidence of pupillary involvement.
External compression of the third nerve affects parasympathetic fibres surrounding the outermost region of the third nerve. This compression results in an inability to constrict the pupil, making it appear fixed and dilated (often referred to as a ‘blown pupil’).
“Medical” third nerve palsy results from involvement of the vaso vasorum, which is involved in supplying the central area of the third cranial nerve. This results in pupillary involvement arising much later. Common causes of “medical” third nerve palsy include those affecting microvasculature, such as diabetes and atherosclerosis.
Most common causes of large artery occlusion (ie. TACS, PACS)
The two most common causes of large artery occlusion are cardioembolic (e.g. from AF), or plaque embolization (e.g. from significant carotid disease).
What test rules out carotid artery disease as a cause of stroke?
Carotid dopplers
In this case, carotid dopplers were normal, this rules out carotid artery disease, as you would still be able to see a ruptured plaque had that embolised previously.
Where is Wernicke’s area located?
Left temporal lobe
Damage to Wernicke’s area results from occlusion of which artery?
MCA
Consequence of damage to Wernikes area
Damage caused to Wernicke’s area results in receptive, fluent aphasia. This means that the person with aphasia will be able to fluently connect words, but the phrases will lack meaning. This is unlike non-fluent aphasia, in which the person will use meaningful words, but in a non-fluent, telegraphic manner.
What is receptive aphasia and what causes it?
Patients will not be able to respond to questions asked of them and will respond with fluent sentences that do not make sense
Patients are not aware that their speech does not make sense
Patients will be repetitive in their speech
Damage to Wernicke’s area - area located in the left temporal lobe and is responsible for the ability to understand speech. It is supplied by the left middle cerebral artery and therefore strokes that affect this vascular territory can result in receptive aphasia.
Where is Broca’s area and what is it involved in?
The left frontal lobe is the location of Broca’s area, which is involved in the expression of speech (written and spoken word).
Damage to Broca’s area results in expressive aphasia, in which the patient can understand speech but is unable to communicate their own thoughts.
What is expressive aphasia and what causes it?
Damage to Broca’s area results in expressive aphasia, in which the patient can understand speech but is unable to communicate their own thoughts.
Non fluent type
MCA stroke
What do strokes affecting the left occipital lobe typically cause and why?
The right occipital lobe is involved in the processing of visual stimuli and strokes affecting this region would typically result in isolated homonymous hemianopia.
Lesion of left vs right hemisphere
As a general rule, a lesion of the left hemisphere will cause dysphasia whilst, in the right hemisphere, it will cause neglect, visuo-spatial and cognitive problems.
(99% right handed patients and 30% left handed)
Alteplase is recommended for treating acute ischaemic stroke in adults in what circumstances?
Alteplase is recommended for treating acute ischaemic stroke in adults if:
treatment is started as soon as possible within 4.5 hours of the onset of stroke symptoms and
intracranial haemorrhage has been excluded by appropriate imaging techniques
CHA2DS2-VASc and HAS-BLED tools to guide anticoagulation in patients with AF
TOAST stroke classification
Large-arteryatherosclerosis(embolus/thrombosis)
Cardioembolism (high-risk/medium-risk)
Small-vessel occlusion (lacune)
Stroke of other determined etiology
Stroke of undetermined etiology
- Two or more causes identified
- Negative evaluation
- incomplete evaluation
What is the ABCD2 score risk assesment
ABCD2 score for stroke risk assessment after a TIA
High risk groups (ABCD2>4, multiple TIAs
[>2 in previous 7 days], patients in AF or
on anticoagulants) will require urgent
review, i.e. within 24 hrs
In principle all TIA patients should be
seen urgently wherever possible since as
noted earlier the TIA scenario is loaded
with opportunities for secondary
prevention when a TIA is diagnosed
