week 9 patho intracranial regulation Flashcards
what are some things that affect intracranial regulation
impaired blood flow
damage to brain tissue
compromised neurotransmission (loss of neurons in the brain)
impaired glucose regulation
what happens when intracranial regulation is affected
cerebral edema and increased ICP
how is cerebral edema and ICP related
one will most likely cause the other (ex. if you have high ICP it will probably cause cerebral edema)
what are the three parts of the brain compartment
- brain tissue (78%)
- blood (12%)
- cerebrospinal fluid (10%)
what is the Monro-kellie doctrine
describes how the body maintains normal pressure in the skull
ex. increased pressure in one area will most likely decrease pressure in another or ICP will increase
which 2 things does the brain depend on for normal functioning
- consistent supply of blood (for oxygen, nutrients, and glucose)
- healthy heart and lungs to pump oxygenated blood to the brain
why does the brain need a consistent supply of blood
because the brain cant store oxygen and glucose, so it needs a constant flow of it
what is cerebral perfusion pressure
pressure needed to ensure adequate brain tissue perfusion
what who pressures make up CPP (cerebral perfusion pressure)
MAP (mean arterial pressure) minus ICP
MAP: forces blood into the brain
ICP: compresses blood flow in the arteries and pushes blood flow out
what is auto regulation
brain regulates its own blood flow by vasodilation and vasoconstriction
high CO2: vasodilation
high O2: vasoconstriction
pH: based on acidiy and alkalinity of brain
what are the two compensatory mechanisms of the brain
CSF volume: brain will produce more CSF or move it around
Autoregulation
what is normal ICP
5-15 mmHg
what things could cause failure of auto regulation
severe hypotension/shock, now the only thing that determines cerebral perfusion is BP alone
what will happen to a hypotensive patient if auto regulation fails
they will have severe cerebral ischemia
what would happen to a hypertensive patient if auto regulation is lost
stroke or rupture/ v high ICP
what can increase ICP for the brain tissue, blood and CSF
brain tissue: tumour, abscess, cerebral edema
blood: intracranial hemorrhage, intracranial hematoma
CSF: hydrocephalus
what is hydrocephalus
Hydrocephalus is a neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles (cavities) deep within the brain
what are the three types of cerebral edema
vasogenic: permeability of capillary endothelium is shitty and it leaks all over
cytotoxic: cells become hypoxic = swelling from Na/K pump failing
interstitial: obstruction causes cerebrospinal fluid to leak and move around
what causes vasogenic cerebral edema
permeability of endothelium sucks d/t injury, proteins leak into intravascular space
what are some causes of vasogenic cerebral edema
brain tumours, head trauma, abscesses, tocins
how does cytotoxic cerebral edema happen
injury to brain tissue causes hypoxia to the cells, cells stop working and Na/K pump fails
this causes sodium retention and water moves into the cells, causing swelling and loss of cellular function
how does interstitial cerebral edema happen
hydrocephalus causes obstruction, prevents cerebral spinal fluid from leaving ventricles. this leads to increase in intraventricular pressure which pushes CSF into extracellular space.
what are the four types of brain hemmorhage
epidural hemmorhage (above dura mater)
subdural hemmorhage (below dura meter)
subarachnoid hemmorhage (below arachnoid)
incracerebral hemorrhage (in the brain)
how does high ICP lead to brain herniation
cerebral edema, compression of brain vessels, tissue, and ventricles, decreased blood flow, tissue hypoxia, death of brain cells, acidosis, impaired auto regulation, brain stem compression, brain herniation
what is brain herniation
basically brain tissue shifts from one space to another to make room for extra things.
how does high ICP cause ocular issues
swelling compresses oculomotor nerve (cranial nerve 3)
how does high ICP affect LOC
pressure pushes on the brain stem (always check LOC in neuro patients)
whats cushings triad
late signs of intracranial pressure affecting systemic vital signs
- increased blood pressure
- decreased heart rate
- irregular respiratory rate (cheyne stokes)
what are the three signs of cushings triad
hypertension
bradycardia
bradypnea
whats the difference between decorticate posturing and decerebrate posturing
decorticate: arms flexed and pulled inward (means damage to both corticospinal tracts)
decerebrate: arms extended with wrists pronated and fingers flexed (VERY BAD, means damage to brain steM)
how does high ICP cause vomitign
direct pressure on vomiting centre (medulla)
usually projectile vomiting with no nausea
what is bacterial meningitis
inflammation of the meninges. bacteria enters the brain and crosses BBB, cytotoxic agents come in and make BBB more leaky which causes cerebral edema and increase in ICP
which people does bacterial meningitis usually occur in
infants, older adults, high risk populations
why is bacterial meningitis more prevalent in the winter and spring
because they’re secondary to vital and respiratory disease
what are the two most common types of meningitis
pneumococcus meningitis and meningococcal meningitis
what is a positive kerning sign
you bend the knee up and down and it causes pain (sign of bacterial meningitis)
what is nuchal rigidity
stiff neck (also associated with bacterial meningitis)
