rrd 10 Flashcards
neurological system
cerebral blood flow is normally maintained at a rate that matches ___________, ensuring a constant supply of _______.
- metabolic needs of brain
- oxygen and glucose and waste removal
maintenance of effective cerebral blood flow is dependent on keeping what 2 forces in balance?
- cerebral perfusion pressure (CPP)
- intracranial pressure (ICP)
cerebral perfusion pressure (CPP)
pressure required to get oxygenated blood into the brain to perfuse the cells of the brain
if CPP is too low or high, the result is?
- ineffective perfusion
- ischemia to brain
- cellular hypoxia
- cell injury and death
- loss of cell membrane integrity
- water + other cell contents released
- cerebral edema + increased ICP
- further loss of effective perfusion
if CPP is either too high OR too low, it can lead to?
- cerebral edema
- increased ICP
intracranial pressure (ICP)
totality of pressures in the brain
- atrial & venous pressures (blood) + CSF pressure + Brain (tissue)
bc cranium is a bony structure, _________ in pressure in the brain can be tolerated.
very little increase
some degree of pathologic alteration in brain fxn (decreased LOC, impaired sensorimotor fxn, etc.) can be expected from?
small amt of increased ICP
the main culprit in causing increased ICP (IICP) and loss of balance btw ICP and CPP is?
cerebral edema
example of situation causing cerebral edema
- ischemia from blockage (plaque or stricture) of an artery in brain or going into brain (carotid)
- cells hypoxic
- swell, increased vascular permeability
- edema
- increased ICP
- decreased CPP
- brain ischemia
what can cause CPP to go out of balance?
- HTN (high)
- hypotension (low)
- blockage of arterial flow into brain (low)
what can cause ICP to go out of balance?
- head injury
- brain tumor
- brain attack/stroke
- infections, acid/base imbalance, hypoxemia from resp disorders, meningitis can lead to inflammation of brain tissue
brain attack
process of any interruption of the normal blood supply to a part of the brain or entire brain, resulting in damaged brain tissue
other names for brain attacks
- strokes
- CVAs (cerebrovascular accidents)
most common underlying etiologies of brain attack (BA) are?
- atherosclerosis of cerebral arteries and/or of incoming arteries (carotid+ vertebral)
- HTN
- others: brain aneurysms, heart probs that lead to low CO -> decreased blood to brain
risk factors of BA
- preexisting hx of atherosclerosis and/or HTN
- older age
- fam hist
- diabetes
- lifestyle choices (smoking, high fat diets)
categories of BA are based on? what are they?
- underlying mechanism
- ischemic cause vs hemorrhagic cause
S/S ____ depend on whether a stroke is ischemic or hemorrhagic. TX ____ depends on knowing which kind is occurring, which is determined by ___.
- does not
- does
- CAT scan or MRI of brain
no matter what mechanism the BA falls under, ultimately the actual negative effects of a stroke are still?
- cerebral edema
- IICP
ischemic brain attack cause is usually the ________ of arteries supplying brain (_______ arteries) or ______ arteries themselves.
- narrowing or blockage
- carotid or vertebral
- intracranial
ischemic brain attack is usually related to ____ and other processes that damage arterial walls, resulting in same process as ____ formation in coronary arteries
- atherosclerosis
- plaque
patho of ischemic brain attack
- diminished perfusion to brain tissue
- cellular ischemia
- infarction (cell death)
- inflammatory process
- swelling, cerebral edema
- increased ICP
- further decrease in perfusion
thrombotic stroke
occurs from a clot or plaque that blocks off the artery in which is has developed and causes ischemia distally
embolic stroke
when fragments that break from an arterial thrombus travel downstream until they get stuck in a smaller artery and cause ischemia to brain distally
arterial fibrillation leading to thrombotic/embolic event
- afib
- disorganized motion of LA allows some incoming blood to pool & promotes stasis
- small clots develop in atria
- break off
- travel to brain via carotids
- lodge in cerebral artery
- ischemia/infarct to distal tissue
atherosclerosis of carotids causing thrombotic/embolic events
- carotids common place for thrombi to develop
- small clots can break off from these
- travel downstream
___ emboli can cause thrombotic/embolic events, usually ______, during _____.
- air
- iatrogenic
- surgury
clots around ____ or ___ valve prosthesis or _____ from around affected valve can cause thrombotic/embolic event.
- mitral or aortic
- vegetation
_____ artery plaque can develop in the _____; if breaks, free, can lodge in _____ arteries to cause thrombotic/embolic events.
- intracranial
- circle of Willis
- smaller
transient ischemic attack (TIA) can happen in either thrombotic or embolic situation and cause same S/S as a fully-evolved stroke, but?
does not damage brain tissue bc is transient (i.e. temporary - resolves itself quickly)
S/S from TIA only last _____ and have ______ neurologic deficit (TIAs last between _______).
- < 24 hrs
- no lasting
- 10 mins to < 24 hrs
TIAs are often a warning of?
more serious, fully-evolved stroke can occur at later date
hemorrhagic stroke is usually caused by?
effects of blood that leaks out directly onto brain tissue
in most areas of the brain, there is normally ____ blood directly on brain tissue. it is carried in _____ and when arrives at ____, O2 + nutrients diffuse into tissue cells & CO2 + other wastes diffuse out of cells.
- NO
- arteries and veins
- capillary beds
what happens when an intracerebral aneurysm begins to leak blood onto brain tissue?
- blood irritates the tissue
- inflammatory process
- swelling, cerebral edema
- increased ICP
- cellular ischemia, injury, and/or infarction of the surrounding area
causes of hemorrhagic brain attack
- pressure of HTN
- weakened arterial walls from atherosclerosis
- aneurysms
- congenital vascular malformations
- bleeding into a tumor
- coagulation disorders
S/S of BA depend on?
- where the brain attack occurs
- which blood vessel is affected
- what part of the brain does the vessel supply blood to
three general areas of brain tissue are?
- brainstem
- cerebellum
- R/L hemisphere of the cerebrum
major cerebral blood supply is
- vertebral artery merges w/ basilar artery -> supplies blood to brainstem + cerebellum
- R/L internal carotid artery forms R/L middle cerebral artery (MCA) -> supplies blood to R/L hemisphere of cerebrum
how to assess patient for S/S of various kinds of BA
- assess pt’s autonomic status (include LOC (level of consciousness and mental status)
- assess sensorimotor system
(a) assess sensorimotor above the sholders
(b) assess sensorimotor below the shoulders - assess reflexes
autonomic status includes?
involuntarily controlled neuro fxnz
normal VS (_______) are often one indicator that areas in the brain that control respiration (_____) are working normally, that is having _______.
- BP, HR, RR, temp
- brainstem
- no cerebral edema and IICP
levels of consciousness (LOC)
the brain’s ability to respond appropriately to the environment
changes in LOC are often the first sign of?
neurologic event or a worsening of an existing neurologic illness
expected LOC includes?
- being alert/easily arousable to alertness if asleep
- being orientated X 4 (self, time, place, events)
- following commands appropriately
- having norm speech (speech centers in brain ok)
- conversing appropriately (cognition, mental status ok)
abnormal LOC findings often means that?
there has been an event that led to increased cerebral edema and IICP in certain areas of the brain
abnormal of LOC includes?
- not being alert: from being lethargic to inability to awaken the patient at all (coma)
- not orientated to some or all of self, time, place, events
- doesn’t follow commands
- speech might be garbled or no speech at all
- verbal responses/conversational efforts show inappropriate or dysfxn mental status (confusion or behavior like withdrawal/aggression)
sensorimotor
movement and sensation are intricately related
expected sensorimotor findings upon assessment include
- norm sensation, muscle tone, movement that is also…
- symmetric, the same bilaterally (same on both R/L sides of body)
the ___ cranial nerves (CNs) branch out from the brainstem (______) and rule ______ status ____ the shoulders.
- 12
- midbrain, pons, medulla
- sensorimotor
- above
lesion
- gen term for problem
- tumor, ischemia, localized increase in cerebral edema and pressure, bleeding, etc.
focal
one area of the brain is affected
CN VII
- facial nerve
- controls facial movement and expression
if there is a focal lesion caused by BA, tumor, or bleeding in RIGHT hemisphere, expect to have _______ findings, with the defect manifesting ______ on the ________ side.
- asymmetric
- unilaterally
- opposite/contralateral
what happens when there is a focal cerebral edema around the right CN VII?
- CN VII allows a smile
- facial drooping on left side of the mouth
ipsilateral
same side
CN II
- optic nerve
- responsible for transmitting visual images to the brain
what happens if there is a focal cerebral edema around the right CN II?
- visual defects in the two left halves of BOTH eyes
- homonymous hemianopia
CNII (optic) and CNIII (oculomotor) control the _________. when norm fxn is present on both nerves, _____ pupils should respond equally to ______. both pupils should constrict to _________.
- pupillary light reflex
- both
- light
- to the same size
bilateral loss of the pupillary light response
- both pupils are either fixed and dilated OR fixed and pinpoint
- indicates a lesion in the brain stem
certain parts of the sensorimotor apparatus that connects brain to spine to muscles in torso, arms, legs (below shoulder) are called?
corticospinal and spinothalamic tracts
corticospinal tracts
- descending (motor) tracts
- aka pyramidal tracts
there are bundles of long ____ that originate in the _____ of certain areas of the _____ cortex on either side of the brain.
- axons
- cell bodies
- motor
axons in certain areas of the motor cortex cross over, or ________, from their point of origin in the _______ to the opposite side of the body at the _________, giving them their _____ look.
- decussate
- cerebral cortex
- junction btw spinal cord + brain stem
- pyramid
the pyramidal tracts carry impulses that produce ________ from brain via spinal cord to various _______ to _______ between nerves and muscles.
- voluntary movements of purpose + skill
- peripheral spinal nerves
- neuromuscular junctions
spinothalamic tracts
ascending sensory tracts
spinothalamic tracts carry sensations of? from where to where for processing?
- pain, temp, crude + light touch
- body to brain (thalamus)
T/F the spinothalamic tracts do not cross over from one side of the body to the other side of the brain.
FALSE: they do similar to corticospinal tracts, just in a different area
if there is a focal lesion related to corticospinal or spinothalamic tracts in the brain, expect to see?
asymmetric sensorimotor changes
the pathologic changes of focal lesion related to corticospinal/spinothalamic tracts will usually be?
unilateral, on the contralateral side of the body because of decussation
a pt with a tumor on the right side of the brain would have decreased strength + sensation of arms + legs on what side of the body?
contralateral/opposite side
normal peripheral reflexes include?
- expected degree of response
- equal bilaterally (symmetric)
- reflects good connections in reflex arc of spine
- norm interpretation in the brain
norm central reflexes include?
appropriate cough, swallow, gag, etc.