neuro pt. 1 Flashcards
what makes up the CNS
brain
spinal cord
what are the 3 layers of the meninges
dura
arachnoid
pia
what is the space between the skull bone and dura
epidural space
what is the space between the dura and arachnoid
subdural space
what is the space between the arachnoid and pia
subarachnoid space
outermost layer of meninges directly beneath skull
dura mater
what does a rupture of the dura mater result in?
epidural or subdural hematoma
which layer of the meninges circulates CSF and contains cerebral vasculature
arachnoid mater
rupture of an artery in the arachnoid mater cuases what?
subarachnoid hemorrhage
what absorbs CSF for removal
arachnoid villi
what does a blockage in arachnoid villi cause?
communicating hydrocephalus
which layer of meninges forms the choroid plexus within ventricles and is responsible for production of CSF
pia mater
what is responsible for production of CSF
choroid plexus within the ventricles
what is csf reabsorbed by?
arachnoid villi
what does csf function as?
shock absorber and protects brain tissue
what does csf contain?
glucose!!
amino acids, other nutrients
what are the 2 major sets of vessels that supply the brain?
2 internal carotid arteries
2 vertebral arteries
what is a circular network that permits blood to circulate between hemispheres and anteriorly and posteriorly
circle of willis
what should you expect to find in CSF?
1) blood
2) glucose
3) cloudy fluid
4) green fluid
2) glucose
what is pressure in the cranial vault called
ICP
3 components of ICP
1) blood volune
2) brain tissue volume
3) CSF
describe the monroe-kellie doctrine
-ability of brain to self regulate
-inc. in volume of one intracranial component must be compensated by dec. in one or both other componensts
-if this doesn’t occur, ICP inc.
how is autoregulation accomplished?
changes in diameter of vessles (vasoconstriction/dialtion)
what happens when BP increased with impaired autoregulation
it can inc. cerebral blood flow and ICP
what is cerebral blood flow (CBF) affected by?
cerebral perfusion pressure (CPP)
what shows adequacy in delivering oxygen to the brain
cerebral perfusion pressure (CPP)
what is the formula for calcualting CPP
MAP - ICP = CPP
describe the compensatory mechanism of pressure autoregulation (related to MAP changes)
inc. MAP -> cerebral vasoconstriction -> dec. blood flow
dec. MAP -> cerebral vasodialtion ->inc. blood flow
describe the compensatory mechanism of metabolic autoregualtion (CO2 changes)
inc. CO2/lactic acid = vasodialtion / inc. flow
dec. CO2 = vasoconstriction / less flow
what are the 3 things that effect ICP
cerebral blood flow
CSF
brain tissue volume
what component of ICP does cerebral edema effect?
brain tissue volume
what is cerebral edema caused by
brain trauma, CNS infection, brain tumors, CVAs
what secondary complication does cerebral edema lead to?
impairs circulation leading to hypoxia
what are the 2 types of cerebral edema
vasogenic
cytotoxic
displacement of brain tissue through structures in the skull because of inc. ICP
central herniation
which symptoms occur in central herniation once compensatory mechanisms are exhausted?
cushing’s triad
bilateral pupillary dilation!!!
flaccid paralysis
is cushings triad a sign of imminent death?
yes
s/sx of cushing’s triad
-inc. pulse pressure (systolic inc., diastolic dec.)
-bradycardia (30-40)
-abnormal resp pattern (not if vented)
what does cushings triad indicate?
brainstem compression
imminent death
when is an ICP monitoring device not indicated
mild/mod brain injury (awake)
complications of ICP monitoring devices
infection
obstruction
hemorrhage
mispalcement
nurse cares for vented pt. post head injury. HR drops from 70 to 34 and BP = 205/76. Nurse suspects what?
1) cytotoxic edema
2) vasogenic edema
3) cushing triad
4) meningitis
3) cushing triad
