Brain injury Flashcards
What are the two types of injuries that can occur to the head/brain?
Primary/direct injuries and secondary (subsequent injuries)
What is a primary injury?
also known as direct injury
- damage caused by impact
What is a secondary injury?
occurs because of other factors such as edema, infection, ischemia
What is a mild brain injury?
a concussion, may or may not lose concsciousness
What is a moderate brain injury?
hemorrhages, edema, cognitive/motor dysfunction
What is a severe brain injury?
extensive tissue damage, coma, hematomas
What is the worst brain injury?
brain death and persistent vegetative state
What is a stroke?
syndrome of acute focal neurologic defecit from a vascular disorder that injures brain tissues
What brain injury is the leading cause of mortality and morbidity?
strokes
What is also referred to as a brain attack?
a stroke
brain attack = heart attack
*** time is of essence
What are the risk factors of a stroke?
- increases with age, greater in men, african americans
- heart diseases (hypertension, atrial fibrilation, high cholesterol), sickle cell disease, diabetes
- substance abuse: alcohol, cocaine, smoking
What are the two types of strokes?
- ischemic stroke
- hemorrhagic stroke
What is the prevalence of an ischemic stroke?
it is the most common type of stroke (70-80%)
What happens during an ischemic stroke?
the heart pumps blood to the tissues, a blood clot stops the blood supply to the brain causing a decreased amount of oxygen getting to the brain, high cholesterol levels deposit in arteries (can block the artery completely) and then blood doesn’t reach the brain (ischemia)
What is hypoxia?
deprivation of oxygen with maintained blood flow
What are ways hypoxia can occur?
decrease atmospheric pressure
carbon dioxide poisoning
anemia
What happens if the brain isn’t receiving enough oxygen?
the brain is only 2% of the body weight but uses 20% of the oxygen and fuel
If lack of oxygen - mild euphoria or drowsiness, and impaired problem solving skills
*May not be lethal
What is ischemia?
reduced/interrupted flow, decrease oxygen, decreased glucose, increase wastes (because the blood isn’t taking the waste from the brain, may be focal (stroke) or global (cardiac arrest)
What can happen during ischemia?
It often leads to unconsciousness if it lasts 2-4 minutes
50-75% of the energy by the brain is used to maintain ionic gradients
What are the three ionic gradients effected by ischemia?
- potassium out: hyperexcitability (more K+ oustide cell) of the membrane leads to convulsions
- sodium accumulates inside: neuronal and interstitial edema leads to cell destruction (because osmolarity is increased)
- calcium in (i.e. more calcium inside cell): releases NT/enzymes which lead to cell destruction
What if the threshold of injury isn’t reached during an ischemic attack?
the damage is reversible if you manage to revive the person rapidly
How can you treat a person with an ischemic stroke?
provide oxygen so the metabolic demands decrease, maintain glucose
- if you cool down the body temperature below normal (32-34 degrees celsius) the brain’s glucose (metabolic requirement) goes down so if the patient goes no longer than four minutes they may be able to be revived
During ischemia there can be an overstimulation of receptors of excitatory amino acids, what does this mean?
Gultamate (mostly astrocytes and glial cells) inside of the cell (ICF) has 16X more glutamate than outside, ischemia immobilized transport systems (i.e. no 02, no ATP, carrier molecules don’t work) so glutamate starts leaking out of the cell increasing ECF concentration, glutamate binds to NMDA receptors allowing calcium inside the cell causing a whole cascade of events which will destroy the cells
How can you prevent damage due to glutamate during ischemia?
Inhibit excitatory amino acids synthesis/release, block NMDA receptors (glutamate receptors), stabilize membrane potential (lidocaine/barbituates), block enzymes causing cell death
- a positive feed back cycle - if you block NMDA receptors glutamate can’t act on them so calcium won’t come in
IS survival likely during a hemorrhagic stroke?
NO
What are the characteristics of a hemorrhagic stroke?
- fatal, spontaneous hemorrhage in brain tissues
- occurs suddenly, during activity
- due to rupture of blood vessels (aneurysms), leading to edema, compression of brain tissue and vasospasm
What are some symptoms of hemorrhagic stroke?
- vomiting
- headache
- paralysis
- sensory and mental changes
What is the progression of a hemorrhagic stroke?
- progresses rapidly to coma and death
What are the manifestations of stroke?
- depends on affected cerebral artery, area supplied (smaller region defecits may be minor, larger region may have larger defecits) and adequacy of collateral circulation (if entire brain is supplied by a few arteries, one artery is blocked so one part of the brain may be effected, others not)
What are the causes of hemorrhagic strokes?
- advancing age
- hypertension leading to higher blood pressure which may cause an aneurysm
- arteriovenous malformations, coagulation disorders
What are the three types of deficits that can occur from strokes?
- motor defecits
- language and speech defecits
- cognitive deficits
What is motor deficit?
weakness/ paralysis on contralateral (opposite side because of the split by the corpus callosum) side (hemiparesis), face, arm, leg
What are language and speech deficits? What are the two types?
Dysarthria: imperfect articulation, changes in voice quality/ pitch
Aphasia: inability to communicate spontaneously or to translate thoughts/ideas into meaningful speech
What are cognitive deficits? What are the three types?
Memory loss
Hemiinattention/hemineglect: inability to attend to and react to stimuli from other side
Apraxia: impaired ability to carry out learned motor activities
Agnosia: impaired recognition
When a patient (men) undergo a stroke and only shave or wash one side of face, what type of cognitive defecit is this?
hemiinattention/hemineglect