Stroke Epidemiology And Patho Flashcards
Definition of Stroke by WHO:
Rapidly developing signs and focal disturbance of cerebral function, with signs lasting 24hrs or longer, leading to death with no apparent cause other than of vascular origin
Doesn’t include ischaemic attacking or haemorrhage/infarction related to infection or tumour.
Ischaemic = 90% HAemorrhagic = 10%
Epidemiology of Stroke: In Australia
53 000 strokes per year
Second leading killer in Australia [after heart disease]
costs AU $2.4billion
89% of acute stroke patients in Aus are admitted to hospital
Men at 30% greater risk than women early in life, but woman @ greater risk later
Rate of stroke unchanging, although mortality and severity declining slowly.
Epidemiology of Stroke: Risk Factors for Stroke
Poor diet High cholesterol High BP Sedentary lifestyle Smoking Stress Drug use Family history Diabetes Obesity
Epidemiology of Stroke:
Risk of stroke increases exponentially with age in adult hood
- 55-59 years of age: risk increases ~5% a year
- 80-84 years of age: risk increases ~25% a year
2 out of 10 people die within 1 months of stroke
3 out of 10 die within 1 year
5 out of 10 die within 5 years
Decreasing risk of dying as more time passes following stroke
Subarachnoid or I trace reveal haemorrhage is more likely to cause death than ischaemic stroke
Pathophysiology of Stroke
Impaired neurological function occurs from restricted blood supply [ischaemia] or bleeding or pressure injury
Affects multiple systems, depending on area of brain affected - motor and sensory.
The areas of the brain affected by stroke depend on the artery affected: middle cerebral artery [pink], posterior cerebral artery [green], and anterior cerebral artery [blue]
Haemorrhagic strokes caused by blood leaking into the brain [intra-cerebral] or spaces and spinal fluid around brain [subarachnoid]
Ischaemic strokes result form infraction
- thrombotic = localised thrombus or clot on an atherosclerotic plaque.
- embolic= material [embolus] from elsewhere concludes blood vessel.
Pathophysiology : What are some signs of haemorrhagic stroke?
What are some signs of ischaemic stroke?
Altered level of consciousness
Severe headache
Elevated BP
Some signs of Ischaemic stroke are similar, but cerebral blood flow is the primary marker for assessing [need CT and MRI for diagnosis]
Pathophysiology of Stroke: What are the main arteries?
Anterior, middle and posterior cerebral arteries - there are left and right arteries supplying each hemisphere
Cerebellar arteries supply cerebellum
Occlusion to artery on one side will affect the opposite side of the body, as a general rule
Pathophysiology of ACA lesion, Left MCA, Right MCA:
ACA lesion:
- lower limb [LL] hemiparesis
- upper limb [UL] hemiparesis/paralysis (less severe)
- hemisensory loss (LL>UL)
Left MCA= withdrawn, anxious, depressed, cautious, disorganised, slow movements.
- Right hemiparesis (UL>LL)
- R Hemisensory loss (UL>LL)
- Expressive and/or receptive aphasia
Right MCA= happy, unconcerned, impulsive, overestimates ability, unpredictable, fast movements.
- L hemiparesis (UL>LL)
- L hemisensory loss (UL>LL)
- denies existence of disability
- difficult dressing
Functional Consequences: What are some physical and psychological effects
- > 50% develop major depression, and continuation of unhealthy lifestyle increases risk of future stroke
- Co-morbidities [exist prior to stroke]: obesity, hypertension
- Secondary conditions [result from the stroke]: increased falls, spasticity, memory loss, aphasia, back pain, social isolation, stress
- also, hmemiparesis/quadriparesis or paralysis and impaired balance
Functional Consequences of Hemi Neglect?
Particularly if right side is damaged:
- impairment in parietal region, poor coordinate representation of extra-personal space
- don’t recognise one side of their body
- needs specific treatment, continued ex training
May set up safe challenges or obstacle course- patient learns to attend the the neglected side.
Patient finds and then uses neglected side to assist in bi manual tasks
Pharmacology:
May be using drugs for various conditions.
Blood thinners = increase risk of bruising and bleeding into a joint
Vasodilators = need longer cool down period, increase risk of post exercise hypotension
Antihypertensives = some BP meds cause a decrease HR response, harder to use target HR to determine intensity during cardio training.
Changes seen following Stroke:
Suggested that the brain attempts to deal with sudden loss of motor ability by removing inihibition to surrounding areas.
This CORTICAL INHIBITION is seen in a perilesional intracortical and intercortical capacity.
Motor cortex disinhibition is a phenomenon seen following stroke - weeks
Commonly know as ‘unmasking’, it referees to a loss of inhibitory interneurone input.
Loss of inhibition is temporary: important function implications
Think of this as ‘rebooting’ the system, which places us in a unique position
The lack of inhibitory input gives formerly ‘silent’ synapses the opportunity to influence the connected neurones
Gives us ability to change the motor homunculus - new connections and networks allows us to learn ‘new’ tasks without damaged brain tissue
Significant increases in spasticity and muscle tone
The flexed adducted posture is probably due to reflex activity, excessive motor neurone excitability and abnormal descending drive onto the motor neurone pool
Amplitudes of PICs may not be excessive, but enhanced reflex gain causing synaptic drive may be.
Importance of Exercise in Stroke patients?
Help to integrate back into community, reduce depression, improve social inclusiveness
Increases learning of visual and auditory tasks and improved association of shapes and figures
Improves fatigue resistance to allow to return to work
Minimise weight gain and accumulation of cardiac risk factors
INCREASED SYNAPTIC PLASTICITY- strong evidence that ex + learning is more effective than learning alone - BDNF and GDNF
Exercise Testing for Stroke Patients
Stroke patients should be screened by a physician before commencement of testing/training, and complete PAR-Q
Requires fasting blood draw, resting ECG, resting HR, BP [standing, seated, supind] and basal temp
Graded exercise test should follow before other testing
Exercise Testing for Stroke Patients: Endurance
Normally they have lower VO2 due to hemiparalysis/paresis and loss of muscle mass
A symptom limited test can be performed on treadmill, bike, arm ergo, etc.
If graded ex test showed no irregularities, there is no reason for staged test with continuous BP monitoring
