Stroke Flashcards
What is a stroke?
Stroke is defined as an acute neurological deficit lasting more than 24 hours and caused by cerebrovascular aetiology.
How are strokes subdivided?
Cerebrovascular accidents are either:
- Ischaemia or infarction of brain tissue secondary to inadequate blood supply
- Intracranial haemorrhage
Which type of stroke is most common? Ischemic stroke or haemorrhagic stroke?
Ischaemic stroke accounts for 87% of all strokes, haemorrhagic stroke for 10% and subarachnoid haemorrhage for 3%.
Briefly recap the Circle of Willis
What can cause a distruption of the blood supply in the brain?
Disruption of blood supply can be caused by:
- Thrombus formation or embolus, for example in patients with atrial fibrillation
- Atherosclerosis
- Shock
- Vasculitis
What is a transient ischaemic attack (TIA)?
Transient ischaemic attack (TIA) was originally defined as symptoms of a stroke that resolve within 24 hours. It has been updated based on advanced imaging to now be defined as transient neurological dysfunction secondary to ischaemia without infarction.
What is a cresendo TIA? And what is the risk of this?
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.
Briefly describe an ischaemic stroke and its causes
Ischaemic strokes occur when the blood supply to an area of brain tissue is reduced, resulting in tissue hypoperfusion.
There are several potential mechanisms which can result in an ischaemic stroke including:
- Embolism
- An embolus originating somewhere else in the body (e.g. the heart) causes obstruction of a cerebral vessel, resulting in hypoperfusion to the area of the brain the vessel supplies.
- Thrombosis
- Ablood clot forms locally within a cerebral vessel (e.g. due to atherosclerotic plaque rupture)
- Systemic hypoperfusion
- Blood supply to the entire brain is reduced secondary to systemic hypotension (e.g. cardiac arrest)
- Cerebral venous sinus thrombosis
- Blood clots form in the veins that drain the brain, resulting in venous congestion and tissue hypoxia
Briefly describe a haemorrhagic stroke and its causes
Note: intracerebral and subarachnoid haemorrhage
Haemorrhagic strokes occur secondary to rupture of a blood vessel or abnormal vascular structurewithin the brain.
There are two sub-types of haemorrhagic stroke known as intracerebral haemorrhage and subarachnoid haemorrhage.
- Intracerebral haemorrhage
- Intracerebral haemorrhage involves bleeding within the brain secondary to a ruptured blood vessel
- Intracerebral haemorrhages can be intraparenchymal (within the brain tissue) and/or intraventricular (within the ventricles)
- Subarachnoid haemorrhage
- Subarachnoid haemorrhage is a type of stroke caused by bleeding outside of the brain tissue, between the pia mater and arachnoid mater
What stroke is shown in the image?
Intracerebral haemorrhage.
What stroke is shown in the image?
Subarachnoid haemorrhage.
What stroke is shown in the image?
Ischaemic stroke specifically total anterior circulation stroke (TACS).
Briefly describe the blood flow to the cerebrum
The anterior, middle and posterior cerebral arteries each supply a specific territory of the brain:
- The anterior cerebral arteries supply the anteromedial area of the cerebrum
- The middle cerebral arteries supply the majority of the lateral cerebrum
- The posterior cerebral arteries supply a mixture of the medial and lateral areas of the posterior cerebrum
Briefly describe the Bamford classification system for strokes
The most commonly used classification system for ischaemic stroke is the Bamford classificationsystem (also known as the Oxford classification system).
This system categorises stroke based on the initial presenting symptoms and clinical signs. This system does not require imaging to classify the stroke, instead, it is based on clinical findings alone.
What are the 4 types of ischaemic strokes according to the Bamford classification system?
- Total anterior circulation stroke (TACS)
- Partial anterior circulation stroke (PACS)
- Posterior circulation syndrome (POCS)
- Lacunar stroke (LACS)
How does a total anterior circulation stroke (TACS) present?
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)
How does a partial anterior circulation stroke (PACS) present?
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)
How does posterior circulation syndrome (PCOS) present?
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
How does a lacunar stroke (LACS) present?
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
Briefly recap the Bamford classification system of ischaemic strokes
What are the clincial features of a stroke?
In neurology, suspect a vascular cause where there is a sudden onset of neurological symptoms.
Stoke symptoms are typically asymmetrical:
- Sudden weakness of limbs
- Sudden facial weakness
- Sudden onset dysphasia (speech disturbance)
- Sudden onset visual or sensory loss
What are the risk factors for strokes?
- 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
Briefly describe the FAST tool for identifying strokes in the community
F – Face
A – Arm
S – Speech
T – Time (act fast and call 999)
Briefly describe the ROSIER (Recognition of Stroke in the Emergency Room) in the emergency department tool for idenfitying a stroke
ROSIER is a clinical scoring tool based on clinical features and duration. Stroke is likely if the patient scores anything above 0.
How is a stroke diagnosed?
Use the CT scan to differentiate between ischaemic stroke and haemorrhagic stroke; which must be done before starting thrombolysis in ischaemic stroke and before reversing anticoagulation in anticoagulation-induced intracerebral haemorrhage.
Ischaemic stroke is a clinical diagnosis based on signs and symptoms. A normal CT scan does not rule out a stroke but will rule out intracranial haemorrhage, which must be excluded before starting thrombolysis.