Basics of a stroke Flashcards by Elizabeth McCabe

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

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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)

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What is an intercerebral haemorrhage?

Bleed from a blood vessel
Variables prognosis
Occasionally from an AVM

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What does a intercerebral haemorrhage look like on an MRI?

Immediate appearance
Looks white - as blood and iron are dense
May spread over time

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How does infarction occur?

Thrombus forms at sites of hardened patches of artery
Usually affects the small blood vessels

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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.

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What are the risk factors for an embolism?

Atrial fibrilation
Cardiac failure
Valvular disease
Diabetes
Lipids

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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

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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

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How fast does damage from stroke occur?

1.9 million neurons a minute

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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

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How does a thrombus/embolism get removed in a TIA?

Endogenous throbolytic mechanisms
Degrade or dissolve the thrombis, hence lack of oxygen is temporary.

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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

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What proportion of ‘stroke’ patients in A and E are stroke patients?

50% of patients that present with stroke like symtpoms actually have stroke

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What are some common non-stoke diagnosis with similar symptoms?

Seizure
Syncope
Sepsis
Migraine
Orthostatic hypotension
Labrynthitis

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In differential diagnosis what symptoms are more likley to happen in a stroke?

Acute onset ***
Arm weakness
Leg weakness
Facial Weakness
Speech disturbance

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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 Wire navigation