Chapter 9 Flashcards
stroke
an embolism (blockage) or aneurysm (excess bleeding) in the brain
- results in a tissue of the brain being starved of oxygen and nutrients
immediate effects of stroke
sudden difficulty speaking, blindness in one eye, and numbness and/or weakness, usually on one side of the body
long-term effects of stroke
can cause aphasia (loss of speech), loss of fine motor control, paralysis, or even death
hypertension and stroke
- high blood pressure
- too much flow will cause the walls of passages to thin and eventually burst
risk factors of stroke
- hypertension
- cigarette smoking
- diabetes
- hypercholesterolemia
- overweight/no exercise
arterosclerosis
- “hardened vessels”
- plaques, fatty deposits of cholesterol, accumulate inside arteries on the walls and block the lumen, reducing blood flow
- these plaques can cause clots to form
clot
immune cells traffic to area to remove cholesterol deposits and release substances helping to form the clot
- sometimes these immune cells are activated by drugs, rather than trying to remove cholesterol deposits
thrombus
a clot attached to the artery wall
embolism
a clot floating in the bloodstream
- a floating clot can lodge in an artery, completely blocking blood flow and causing tissue death
- can form anywhere then flow to the brain and cause blockage
aneurysm
occurs when an artery wall balloons under pressure, the weakened wall can subsequently burst
- burst aneurysms are usually fatal
another definition of stroke
an injury to the brain caused by the interruption of blood flow to a focal area of the brain or by bleeding into or around the brain; this causes the sudden onset of a focal neurologic deficit or headache which lasts for at least 24 hours or leads to death
transient ischemic attack (TIA)
like a temporary stroke; caused by a brief interruption of blood flow to part of the brain, resulting in sudden, temporary loss of neurological function
- often called “mini-strokes” or “warning strokes” because they mimic the symptoms of a full-blown stroke but typically resolve within minutes to hours, leaving no permanent damage
types of stroke
- ischemic
- hemorrhagic
ischemic stroke
obstruction of a blood vessel supplying the brain by a blood clot deprives the brain of essential nutrients and if blood flow is not restored quickly leads to irreversible damage to the area of the brain supplied by the blood vessel
- thrombus or embolus
hemorrhagic stroke
bleeding into the brain substance or around the brain
four major subtypes of ischemic stroke
- atherothrombotic
- cardioembolic
- lacunar stroke or small vessel disease
- “other” causes
atherothrombotic stroke
- most common type of stroke
- cause: atherosclerosis of major extracranial (origin of the internal carotid, origin of the vertebral arteries) and intracranial vessels (basilar, carotid siphon, origin of the middle and posterior cerebral arteries)
- major risk factors: hypertension, smoking, diabetes, and elevated cholestrol
surgical treatment of treat angina
- balloon angioplasty
- placement of a stent
balloon angioplasty
a balloon is inflated in the coronary artery to “squash” the plaque and widen the lumen
1) balloon catheter with uninflated balloon is threaded to obstructed area in artery
2) when balloon is inflated it stretches arterial wall and squashes atherosclerotic plaque
3) after lumen is widened, balloon is deflated and catheter is withdrawn
- realized this was a bad idea because a portion of it would detach after balloon is deflated and could flow and cause blockage that causes a stroke somewhere else
placement of a stent
a roll of wire is used to hold open the coronary artery
- same process as balloon angioplasty but made of wire
- put patient on blood thinners to ensure that the blood does not stick to the wire
carotid endarterectomy
surgically remove plaque from carotid arteries
- have to tie off the artery on both ends of plaque
- very risky –> could accidentally cut artery; tying could break the artery
ischemia can be classified as…
acute or chronic
- based on duration and onset of symptoms
acute ischemia
- sudden onset: occurs abruptly and rapidly, often with severe symptoms
- short duration: typically lasts for a relatively short period, ranging from minutes to hours
- causes: primarily caused by a sudden blockage of blood flow such as thrombosis, embolism, trauma
- treatment: focuses on restoring blood flow quickly to prevent permanent damage; may involve medications to dissolve clots, surgical procedures to remove blockages, or lifestyle changes to reduce risk factors
edema
swelling due to water
chronic ischemia
- gradual onset: develops slowly and progressively over time, often with subtle or intermittent symptoms
- long duration: persists for an extended period, often months or years
- causes: usually caused by a gradual narrowing of blood vessels due to atherosclerosis or inflammation
- treatment: aims to improve blood flow and manage symptoms; may include medications to widen blood vessels, lifestyle changes to reduce risk factors, and in some cases surgical procedures to bypass or open blocked arteries
cardioembolic
cause: a thrombus can arise from the heart and then tends to lodge at branch points in the cerebral blood vessels
- left atrium
- left ventricle
- mitral or aortic valve
- venous system
- right heart with a right-to-left shunt
lacunar stroke or small vessel disease
- cause: small blood vessels which are the penetrating branches of the middle artery, anterior choroidal, posterior cerebral and posterior communicating arteries, and basilar artery
- risk factors: diabetes and hypertension, which causes thickening of the vessel wall (lipohyalinosis) leading to occlusion
- infarcts are usually small “holes” or lacunes”: putamen, thalamus, internal capsule, basis pontis
multi-infarct dementia
dementia caused by recurrent events of lacunar strokes
“other” causes of ischemic stroke
- blood disorders such as hypercoagulable state or hemoglobinopathy
- dissection of the blood vessel wall due to illicit drugs
- autoimmune process (vasculitis)
- obstruction of the veins (venous sinus thrombosis)
pathophysiology of ischemic stroke - microenvironment of stroke
- blood vessel occlusion
- ischemic penumbra
- progression: if blood flow isn’t restored , penumbra shrinks, and central core expands over time
- treatment: thrombolytic agents; must be administered within 3 hours of symptom onset for benefit
blood vessel occlusion in pathophysiology of ischemic stroke
- central core experiences extremely low blood flow
- tissue in the core is irreversibly damaged
ischemic penumbra in pathophysiology of ischemic stroke
- surrounds the core
- reduced metabolic activity
- tissue remains visible is perfusion is restored
cellular mechanisms of injury - microenvironment of stroke
- loss of blood supply: decreased energy production, failure of ionic pumps and mitochondrial injury
- cellular effects: production of free radicals; activation of leukocytes; release of excitatory neurotransmitters; influx of sodium, calcium, and chloride ions; release of proteases that break down cytoskeleton and DNA
microenvironment of infarct
- immediately following stroke astrocytic glial cells are activated and migrate to the peri-infarct
- glial scar: physical barrier to nearby neuronal circuits, biochemical barrier containing inhibitors, accumulation of GABA due to reduced uptake via astrocytes
mechanisms of hemorrhagic stroke
- intracerebral
- extracerebral: subarachnoid hemorrhage, subdural hematoma, epidural hematoma
hemorrhage stroke
bleeding occurs within the brain tissue or around the brain
intracerebral hemorrhage
- bleeding into the brain parenchyma
- small percentage arteries (in the putamen, thalamus, pons, and cerebellum) are affected and ruptured, leading to bleeding
- causes: hypertension, arteriovenous malformations, bleeding into a brain tumor, medications such as warfarin, hematologic disorders
- symptoms: patients may experience a headache, nausea or vomiting, and a focal neurological deficit
- diagnosis: a CT scan is needed to rule out ischemic stroke
subarachnoid hemorrhage (SAH)
bleeding occurs in the space between the brain and the thin tissues covering it, often due to aneurysm rupture
extradural hemorrhage
- caused by damage to middle meningeal artery (and vein)
- often from minor head trauma
- bleeding forms a hematoma between skull and dura
- slow formation; symptoms may be delayed hours or days
