What is a stroke?

1
What is a stroke?

• A stroke occurs when an artery supplying the
  brain
• either blocks or bursts

2
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 lt24 hours

Stroke 2009402276-2293, Stroke.
2011423612-3613
3
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 lt24 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 2009402276-2293
4
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/patient
  s/about-stroke/stroke-statistics/)

5
3rd Most Common Cause of Death
6
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
• 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

7
Symptoms Depend on part of Brain Affected
8
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

9
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

10
Oxfordshire Community Stroke Project
Classification for Haemorrhagic and Ischaemic
Stroke

• TACS
• Visual field loss
• Weakness arm or leg
• Dysphasia or inattention or dyspraxia
• PACS
• Only two of the three symptoms of TACS

• LACS
• Weakness or sensory loss
• No other symptoms
• POCS
• (brain stem or cerebella symptoms)

11
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 3541)

12
Referral for exercise Classification of
Patients (data from STARTER)
13
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

14
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

15
Risk Factors and Causes of Haemorrhage

• Primary Intracerebral Haemorrhage
• Hypertension
• Coagulation disorder
• Aneurysm
• Arterio-venous malformation (AVM)
• Cigarette smoking
• Amyloid angiopathy
• Drug abuse

16
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

17
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)
• Electrolytes (e.g. sodium and potassium)
• Urea and creatinine (kidney function and
  hydration)
• ESR (for inflammation)
• Blood clotting (for haemorrhagic stroke)

18
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)

19
Summary

• Stroke is 3rd most common cause of death
• 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