Transcript gm-L2-Stroke-Introduction_edit-301013

What is a stroke?
A stroke occurs when an artery supplying the brain
either blocks or bursts
Definition of a stroke
• Sudden onset
• Focal neurological disturbance e.g. speech problem,
limb weakness
• Vascular in origin (i.e. blood clot or bleed)
• Definition includes subarachnoid haemorrhage
(bleeding which occurs from a small swelling in blood vessel in
the brain) which presents with severe headache with or
without focal neurology.
• Previously, symptoms had to last more than 24
hours, but the American Heart Association guidelines
(2009) propose that patients with a visible ischaemic
event on magnetic resonance imaging are
categorised as ischaemic stroke even if event lasts
for <24 hours
Stroke 2009;40:2276-2293, Stroke. 2011;42:3612-3613
Definition of Transient Ischaemic Attack
(TIA)
• It had previously been defined as sudden onset of
focal neurological disturbance, assumed to be
vascular in origin, and lasting <24 hours
• However, in 2009, the definition was amended to
include magnetic resonance brain imaging criteria
– a brief episode of neurological dysfunction caused
by focal brain or retinal ischemia, with clinical
symptoms typically lasting less than one hour, and
without evidence of acute infarction on brain
imaging
Stroke 2009;40:2276-2293
How common is a stroke?
• 3rd most common cause of death
• Commonest cause of severe adult disability; 50%
survivors disabled at 6 months
• 120,000 strokes per year in UK
• A stroke occurs every 5 minutes in the UK (www.nhs.uk)
• In USA: about 795,000 suffer a stroke and 140,000 die
each year (http://www.strokecenter.org/patients/aboutstroke/stroke-statistics/)
3rd Most Common Cause of Death
Neurological effects of stroke (and TIA)
• Weakness down one side of body (opposite side of brain)
• Poor balance
• Sensory symptoms (e.g. numbness)
• Speech problems
– Language (usually dominant i.e. left side of brain) (affects both production
of language and understanding)
– Articulation
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Swallowing problems
Visual problems (e.g. double vision, loss of visual field)
Dyspraxia (difficulty with complex tasks)
Perceptual problems e.g. neglect
Memory and thinking
Incontinence
Symptoms Depend on part of Brain Affected
Is it a Stroke or not?
• Other medical conditions can ‘mimic’ a stroke (brain tumour,
seizure, migraine, low blood sugar, infection)
• About a fifth of patients with suspected stroke turn out not to
have had a stroke
• Brain scans essential to exclude some stroke ‘mimics’ (e.g.
Brain tumour) and to differentiate haemorrhagic from ischaemic
stroke
• Two main types of brain scans: Computed tomography (CT) and
magnetic resonance (MR)
• CT is the most accessible type of imaging and is quick to
perform. MR now available in most hospitals, but not all patients
are able to tolerate it
• CT is usually the ‘first-line’ brain imaging-it can identify fresh
blood very easily and so distinguish ischaemic from
haemorrhagic stroke, and it can identify some stroke mimics e.g.
brain tumours
Two Main Types of Stroke
• Haemorrhage (due to bleeding into the brain):
cause about 15% of strokes
• Ischaemic (due to a blocked blood vessel):
cause about 80% of strokes
Oxfordshire Community Stroke Project
Classification for: Haemorrhagic and Ischaemic Stroke
TACS
• Visual field loss
• Weakness arm or leg
• Dysphasia or inattention
or dyspraxia
LACS
• Weakness or sensory
loss
• No other symptoms
PACS
• Only two of the three
symptoms of TACS
POCS
• (brain stem or cerebella
symptoms)
TOAST classification-which
considers aetiology
• Large-artery atherosclerotic infarction,
(extracranial or intracranial)
• Embolism from a cardiac source
• Small-vessel disease
• Other determined cause e.g. dissection,
hypercoagulable states, sickle cell disease
• Infarcts of undetermined cause
(Adams et al Stroke. 1993; 24: 35–41)
Referral for exercise:
Classification of Patients
(data from STARTER)
35
30
25
20
number
15
10
5
0
TACS
PACS
LACS
POCS
Possible descriptions of stroke
when patients referred for exercise
Pathological subtype
• Ischaemic, infarction
• Description of likely
cause e.g. embolic
• Haemorrhagic,
‘intracerebral
haemorrhage’, ‘ICH’,
‘PICH’
Classification
• Oxfordshire Community
classification
• Site of lesion on brain
scan
– Middle cerebral
artery territory,
posterior cerebral
artery territory
Risk Factors for Ischaemic Stroke
Common
• Hypertension
• Diabetes mellitus
• Cigarette smoking
• Atrial fibrillation
• Carotid stenosis
• Cardiac disease
• Alcohol
• High cholesterol
• Obesity
• Reduced physical activity
• Diet
Rarer
• Vasculitis
• Polycythaemia
• Leukaemia
• Hyperviscosity
• Thrombophilias
• Anti-phospholipid syndrome
• Neurosyphilis
• Endocarditis
Risk Factors and Causes of Haemorrhage
Primary Intracerebral Haemorrhage
• Hypertension
• Coagulation disorder
• Aneurysm
• Arterio-venous malformation (AVM)
• Cigarette smoking
• Amyloid angiopathy
• Drug abuse
Causes of Ischaemic Stroke
• Blood clot forms in artery in brain e.g. middle
cerebral, or small deep artery in brain
• Blood clot forms at another site and ‘travels’ to brain
(embolism)
– Aorta (main artery in chest)
– Carotid artery (in neck)
– Heart
Blood Tests for Stroke
• Blood glucose (for diabetes and low sugar)
• Cholesterol
• Full blood count
– Anaemia (low haemoglobin) or polycythemia (too
many red cells)
– White cells (? Infection)
– Platelets (? Too many or too few)
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Electrolytes (e.g. sodium and potassium)
Urea and creatinine (kidney function and hydration)
ESR (for inflammation)
Blood clotting (for haemorrhagic stroke)
Other tests
• Chest X-ray (heart size, lungs)
• Electrocardiogram (ECG)
• Some patients may have carotid Dopplers (to look for
narrowing of carotid artery)
• Some patients may have echocardiography (i.e.
ultrasound of the heart) to look for blood clot in heart
and abnormalities of the heart valves)
Summary
• Stroke is 3rd most common cause of death
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Most common cause of adult disability
85% are Ischaemic (blocked artery)
Symptoms depend on part of brain affected
Oxfordshire Community Stroke Project
Classification frequently used to categorise
patients
• Different causes and risk factors for stroke