Basics of a stroke Flashcards
What are the key features of a stroke?
Rapid onset
Focal loss of cerebral function
May have a global loss of function in the form of a coma or SAH
Lasts longer than 24 hours
Presumed vascular origin
What are the two different types of stroke?
1) Ischemic - thrombis or embolism
2) Hemorrhagic - intercerebral (between brain tissue) or subarachnoid (between pia and arachnoid mater)
What is an intercerebral haemorrhage?
Bleed from a blood vessel
Variables prognosis
Occasionally from an AVM
What does a intercerebral haemorrhage look like on an MRI?
Immediate appearance
Looks white - as blood and iron are dense
May spread over time
How does infarction occur?
Thrombus forms at sites of hardened patches of artery
Usually affects the small blood vessels
What does an infarction stroke look like on an MRI?
Grey area, develops six to 12 hours after the ischemic event starts
Brain tissue goes liquid like in density as ischemic damage occurs.
What are the risk factors for an embolism?
Atrial fibrilation
Cardiac failure
Valvular disease
Diabetes
Lipids
Where are embolism most likley to form?
Why does the prognosis for a stroke vary compared to a thrmobus?
Embolism - carotid artery or heart
Normally larger, blocks larger blood vessels results in more downstream tissue damage/death
What is meant by the ischaemic penumbra in a stroke?
Thrmobus blocks are artery
Regions that die quickly is the necrotic area
Surrounding area that is at risk but is not yet dead is the inschaemic penumbra, this region is also supplied by arteries known as collateral flow
Treatment should focus on resorting and preventing gurther damage to these arteries
How fast does damage from stroke occur?
1.9 million neurons a minute
What is a TIA?
A transient ischaemic attack
Acute loss of focal cerebral function
Or
Acute monocular visual loss (retinal artery blocked)
Lasts less than 24hrs
Indicates an increased risk of stroke, referred for help immediately
How does a thrombus/embolism get removed in a TIA?
Endogenous throbolytic mechanisms
Degrade or dissolve the thrombis, hence lack of oxygen is temporary.
What is the rosier scale in stroke recognition?
ROSIER - recognition of stroke in the emergency room
Generates a score from -2 to 5, higher score means a stroke is more likely.
Based on seizures and syncope (-1 each) then the BEFAST.
Aims to help distinguish between stroke and conditions that share symptoms with stroke
What proportion of ‘stroke’ patients in A and E are stroke patients?
50% of patients that present with stroke like symtpoms actually have stroke
What are some common non-stoke diagnosis with similar symptoms?
Seizure
Syncope
Sepsis
Migraine
Orthostatic hypotension
Labrynthitis
In differential diagnosis what symptoms are more likley to happen in a stroke?
Acute onset ***
Arm weakness
Leg weakness
Facial Weakness
Speech disturbance
What symptoms are less common but still experienced with a stroke?
Visual distrubance
Limb paraesthesia
Nausea
Headache
In differential diagnosis, what symptoms are less likley in a stroke?
Dizziness
Confusion
Loss of consciousness
Convulsive fits
What sort of questions should be asked when taking a history in a stroke case?
Time of onset
Parts of the body effected
Nature of symptoms
Previous TIA or stroke
Past vascular medical history
Family history
Lifestyle
What are some risk factors for TIA and stroke?
Age - more in elderly
Family history
Smoking, alcohol or recreational drugs
Hypertension
Diabetes
Raised cholseterol
Cariovascular disease or blood disorder etc
Atrial fibrillation
What are the different classifications of a stroke?
Anterior (carotid) system TACS / PACS
Posterior (vertebrobasillar) system POCS
Lacunar stroke LACS
What are the features of a TACS?
Total anterior circulation stroke
Affect both the middle and anterior cerebral arteries
Problems with motor or sensory function
Cortical problem - more behavioural and mental function
Hemianopia
What are the features of a PACS?
Partial anterior circulation stroke.
Less severe than TACS only one of the middle or anterior cerebral arteries are blocked
2 of the folllowing: Motor or sensort deficit
Higher cortical dysfunction
Hemianopia
What is a hemianopia?
Partial loss of vision, often in one side of vision
What are the features of a lacunar stroke (LACS) ?
Motor or sensory deficit only
Mostly ischaemic damage to small vessels branching from the circle of willis, effects non-cortical areas.
Mainly only present when multiple areas of damage has occured as each individual damage site is very small
Pons basal ganglia or thalamus
What are the features of a POCS?
A posterior circulation stroke
Isolated hemianopia
Brain stem signs
Cerebellar ataxia
What are some common signs of damage to the middle cerebral artery during stroke?
Parietal, frontal. superior temporal lobes are effected
Causes UMN facial weakness
Hemiplegia - paralysis on one side of the body
Hemianopia
Aphasia
Visuospatial problems
What is aphasia?
Difficulty with language and speech
What are some common symptoms of damage to the vertebral and basilar arteries?
Brain stem and cerebellum damage
Diplopia (double vision)
Disorders of eye movement
Vertigo
Dysphagia, dystarthria (speaking), bulbar weakness
LMN facial weakness
Respiratory failure or coma
Hemi or quadriparesis
What is bamford classification?
Divides people with stroke into four different categories based on symptoms.
Indicates areas where damage was likley occuring and what treatment will be more successfull.
Bedside classification using clinical information
What is thrombolytic stroke therapy?
Giving medication to break down the thrombus.
Given within 4.5 hours of onset, earlier onset has greater prognosis and fewer side effects
Offered to 12% of people with stroke
Has a concern of bleeding, affects 1 in 25 patients, is fatal in 1 in 40.
Medication ins normally alteplase or rt-PA.
What is a thrombectomy?
Surgical procedure to remove blood clots
Involves a wire mesh, inserted trough artery in the groin.
Normally only beneficial when given to patients with a thrombus in a large artery.
Why might a patient not be given thrombolysis?
Bleeding disorder
Not within the four hours window
Previous stroke or TIA within the last three months
Surgery in the last 2 weeks
Taking any anticoagulants or medication complications
Hemorrhagic stroke
What thrombolytic is used in acute stroke?
Alteplase is the only licensed thrombolytic
Also known as r-TPA or actilyse (brand name)
How is alteplase administered?
Box contains:
1 bottle of the drug in the powdered form
1 sterile water for injections
1 transfer canular for injections
Dosage is calculated by weight (0.9mg per Kg up to 90mg)
Dissolve to give a 1mg/ml solution
10% of dose is given IV over 1 minute
Remaining 90% is given by IV over 1 hour.
What are the limitation of IV alteplase?
Generalizability - limited patient window
Major stroke have poorer outcomes
Large blood vessels are difficult to achieve recanalization.
Can increase risk of hemorrhage in larger strokes
What treatment can be used if IV thrombolysis fails?
Intra-arterial clot removal
Intra-arterial thrmbolysis
What is the current criterial for qualifying for intra-arterial therapies after stroke?
Age younger than 60yrs
Major stroke with proximal Middle Cerebral Artery Thrombus
No signs of rapid improvement with thrmbolysis
Request a head CT and
What are some contraindications to IV rtPA?
No change in NIHSS score one hour after administration
3 hour treatment windown has expired, but less than 10 hours means treatment still required
Severe neurological deficits NIHSS over 16
What is NIHSS?
The National Institure for Health Stroke Scale
Uses criteria and scoring system to determine how bad a stroke is
Scored out of 42, a larger number indicates a more severe stroke.
How long does recanalisation in acute ischemic stroke take?
What are the different methods?
8 hours or longer
IV/IA rtPA
Merci Retrieval device - physically removes the clot (pushing pressure - screw shape expanded on far side of clot then pulled towards outlet)
Pneumbra Aspiration device - uses aspiration to remove the clot (sucking pressure)
What are the key concepts in the practicaltiy of endovascular treatment for stroke?
Femoral or radial access is required
Uses a series of catheters - sheath, guide catheter, micro catheter
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