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Neurologic Function Part 2

Terms

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Stroke/Cerebrovascular Accident
The abrupt or rapid onset of neurological deficits resulting from decreased oxygen to the brain.
what % of 1st strokes are fatal?
25%
What % of 1st strokes result in moderate to severe disabilities.
28%
What is the key for strokes?
prevention
What are nonreversible risk factors for stroke?
Gender - male higher
Age - older higher
Race - blacks higher
Heredity
What are reversible risk factors for stroke?
Hypertension is most significant
Cardiac disease
diabetes
blood lipid abnormalities
obesity
abnormal antibodies - autoimmune problem could be cause.
What are some substances that are risk factors for stroke?
Alcohol use
smoking
oral contraceptives (hormones)
substance abuse (cocaine)
What are extracranial factors affecting cerebral blood flow?
Systemic blood pressure
Cardiac output
Blood viscosity
How is systemic blood pressure an extracranial factor affecting blood flow?
Map < 50 or above 150 autoregulation is effected. Leads to ischemic damage from decreased cerebral blood flow.
How does cardiac output affect cerebral blood flow?
When it is decreased by 1/3 it effects cerebral blood flow.
How does blood viscosity affect cerebral blood flow?
Polycythemia vera > COPD pts.; dehydration.
What are intracranial factors affecting cerebral blood flow?
Metabolic factors
Blood vessel condition
Intracranial pressure
What metabolic factors affect cerebral blood flow?
Decreased PO2, increased PCO2, increased HCO3 (?)
What blood vessel condition affects cerebral blood flow?
AV malformation, aneurysms, atherosclerosis
How does ICP affect cerebral blood flow?
IICP increases pressure on blood vessels - blood doesn't flow freely > ischemia.
What are the 4 basic types of strokes?
Thrombosis
Embolism
Intracerebral hemorrhage
Subarachnoid hemmorrhage
Thrombosis defined:
formation of clot in brain which blocks the artery > ischemia.
Describe what happens with thrombosis formation:
Clot forms > decrease perfussion from clot down > ischemia, necrosis, inflammatory response, inflammation increases > more pressure on tissue.
What is the most common type of stroke?
thrombosis - 55-65%
What physical conditions is thrombosis associated with?
diabetes and hypertension
When do thrombosis clots occur usually?
during periods of rest when everything slows down.
What is a warning sign of a thrombosis?
TIA
Which arteries are usually effected by thrombosis?
interior middle cerebral arteries.
What is an embolism?
Clot that floats into area from outside brain and blocks artery. Ischemic damage occurs.
what are some characteristics of emboli?
Beyond lodging get same responses as above. Occur suddenly, not related to activity.
What is a warning sign of emboli?
TIA
What are some causes of emboli?
Cardiac disease (chronic A Fib; Endocarditis after acute MI; valvular disease)or atherosclerotic disease in carotid arteries.
Will emboli reoccur?
Yes, if you don't treat underlying cause.
Intracerebral hemmorrhage...
bleeding into the brain with hemorrhagic damage,
What causes the damage in an intracerebral hemorrhage?
pressure > ischemia, etc. and the results of the body to clean up the area.
What are predisposing factors to intracerebral hemorrhage?
HTN, atherosclerosis > vessels rupture, blood goes into brain > hematoma.
Bleeding into brainstem.
Subarachnoid hemorrhage...
Bleeding into to subarachnoid space due to rupture of intracranial aneurysm or AVM. May also follow head trauma.
Is subarachnoid hemorrhage related to activity?
NO
What is the 1st sign of subarachnoid hemorrhage?
head ache > blood on meninges > sudden > rupture.
What is the prognosis of subarachnoid hemorrhage?
Poor
Why is management of subarachnoid hemorrhage difficult?
Because of vasospasms.
What does temporal development mean in reference to strokes?
Strokes typically progress through stages - develop over time.
What does TIA stand for?
Transient Ischemic Attack
What is a TIA?
brief episode of neurological deficits with no apparent residual damage. Episode last < 24 hours.
What is considered to be the cause of TIA?
vasospasms or microemboli which resolve.
What is a Reversible Ischemic Neurological Deficit (RIND)?
a neurological deficit which occurs suddenly and lasts > 24 hours but leaves no apparent residual effects.
How long does the deficit caused by RIND last?
may last several weeks but usually lasts < 1 week.
Is RIND considered a warning like TIA?
yes
What tests will show cerebral damage even if effects not apparent?
CT or MRI
What is stroke in evolution?
refers to the stroke in which deficits progress over a period of hours or days.
What is a completed stroke?
Deficits remain unchanged for 3 days. At this point aggressive rehabilitation begins unless stroke was due to ruptured aneurysm.
What do the clinical manifestations of strokes depend on?
Location, size of infarct and whether or not there is collateral circulation.
What does the Circle of Willis contain?
2 vertebral arteries
2 carotid arteries
What does the Anterior Cerebral Artery supply?
The medial portion of brain (core)
Limbic system
RAS
Memory
Sensory Speech
Lower body - sensory, motor
What does the Middle Cerebral artery supply?
Surface of brain
Hearing
Judgement, rational thought
Motor speech
Upper body - sensory, motor
What does the Posterior Cerebral artery supply?
cerebellum
brainstem
What are neuromuscular symptoms the result of:
destruction of motor pathways in pyrimidal tract with loss of skilled voluntary movement.
What is the result of right hemisphere damage?
Left sided hemiplegia (paralysis)/paresis (weakness.
Are upper and lower extremities affected to the same degree?
No, can be to different degrees.
When referring to hemi-, you are dividing the body into
Right and left
When referring to para-, you are dividing the body into
upper and lower
What is stroke in revolution?
refers to the stroke in which deficits progress over a period of hours or days.

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