CNS Flashcards
two mechanisms of brain death
anaerobic metabolism
deterioration of ion gradients
critical factor in determining neuronal cell fate
ATP depletion
if we decrease blood flow to the brain
we decrease washout of waste products
causes K+ to leave the cell and Na+, Cl+, and Ca++ to come in
Anoxic depolarization
NT important in learning/memory
glutamate
Excititatoy NT, binds with NMDA receptor to allow Ca++ to flow into cell
Glumamate
Excessive glumamate release with ____________
impaired membrane integrity
Glutamate reuptake is dependent on ____________. When repute fails glutamates now _____________.
ATP
Excitotoxic
Excess glutamate release and Open NMDA receptors leads to
Calcium overload
ca++ overload and swell in
cytotoxic edema and swelling
NMDA receptor activation and calcium overload stimulates nitrous oxide production and body cannot clear
reactive nitrogen species
lipid peroxidation causes
injury to the cell membrane and inflammatory response
formation of arachidonic acid leads to MORE free radials and inflammatory mediators
lipid peroxidation
Work- stimulates to bring in new bold flow and carry out wast products
metabolic vasodilation
influenced by pH, CO2 and O2
metabolic vazodilation
cases hyper perfusion and edema
impaired vasoconstriction
Normal ICP
0-15
can occur with vasogenic or cytotoxic (glutamate or Ca++) edema, space occupying lesions, or obstruction/excess production CSF
increased ICP
cytotoxic edema
increased brain TISSUE volume
Vasogenic Edema
Increased brain TISSUE volume
Ischemia and Necrosis
Increased brain TISSUE volume
obstructive and non-obstructie hydrocephalus
Increase CSF volume
Acidosis
Increased BLOOD volume
High arterial PaCO2
Increased BLOOD volume
papilledema
edema of the optic disc r/t increased ICP
protrusion of brain through an opening on the supporting dura of the brain
herneation
herniation of tentorum cerebeli
transtentorial herniation
herniation around falx cerebri
subfalcine herniation
dependent on the reticular activating system (RAS)
Level of conciousness
responsible for sleep wake transitions and arousal
RAS
Pupil reflex, change in size, shape and reactivity
CN II and III
Eye movements controlled by
CN 3,4,6
oculovestibular reflex:
rotate head side to side
normally turn eyes to opposite direction of head rotation
Dolls eyes maneuver
Positive if eyes do not rotate in the opposite directions
oculovestibular reflex:
inject cold water into ear
cold calorics
tonic deviation of both eyes toward the irrigated side
wisp of cotton touches cornea to illicit a blink response
absent in severely impaired brain function
corneal reflex
Hypothermia used to
decrease brain metabolism, decreases workload and save 02 for the cells that need it
Why do we want CPP >60?
Proper oxygenation and CLEARANCE of waste products
fever, seizures, agitation and pain
increase brain metabolism
focal TBI
Coup - primary area of insult
Polar
Conta coup, acceleration/deceleraton
Diffuse
global axonal injuy to brain, movement of brain in scull “shearing”
above dura mater
epidural
below dura and above arachnoid space
subdural
below arachnoid space
subarachnoid
alteration or loss of consciousness without any evidence of brain damage on CT
Concussion
necrosis, laceration or bruising
Contusion
collection of blood
Intercranial hematoma
arterial
lucid interval
epidural hematoma
bridging veins
symptoms 2-10 days later,
subdural hematoma
bridging veins
rupture of cerebral aneurism, AVM
subarachnoid hematoma
blood spreads throughout CSF causing meningeal irritation, hydrocephalus, headache, vasospasms and ischemia
subarachnoid hematoma
Why do we want to maintain normal PaCO2
to keep blood supply normal and not increase ICP
sudden onset of neurologic dysfunction that leads to area of brain infarction
Stroke
Most common form of stroke
Ischemic
Sudden occlusion of cerebral artery SECONDARY to thrombus formation or emboli
ischemic stroke
atherosclerosis and coagulopathies
thrombotic stroke
cardiac dysfunction or dysrhythmias
embolic stroke
contralateral hemiplegia, hemisensory loss, contralateral visual field blindness
Ischemic stroke
Aim of early thrombolytic therapy
salvaging penumbra
if neurologic deficits completely resolve
TIA
TIA warning sign for
thrombotic disease that may carry a risk for ischemic stroke-
preventative for thrombolytic (ischemic) stroke
ASA, carotid endarterectomy, angioplasty if 70% occluded
brain parenchyma (functional tissue of brain)
hemorrhagic stroke
secondary to chronic HTN
hemorrhagic stroke
morbidity and mortality much hight
hemorrhagic stroke
Tx for Hemmorhagic stroke
CV stabilization, BP management, keep mildly hypertensive at first
Tx for ischemic stroke
thrombolytics, andticoagulants, antiplatelet, enarterectomy, angioplasty, stents
total blindnes to right eye
d/t complete vision of right optic nerve
bipolar hemianopia
midline chiasmal lesion
right nasal hemianopia
lesion of right peichiasmal area
left homonymous hemianopia
lesion or pressure on right optic tract
brain damage to DOMINANT cerebral hemisphere
Aphasia
poor articulation and sparse vocabulary
Broca’a Aphasia
impaired AUDITORY comprehension and speech that is fluent but dost make sense
Wernike Aphasia
Most common cause of subarachnoid hemorrhage
cerebral aneurisms and AVM’s
Marfans
week medial layer of artery
four key points with aneurisms
- weakened MEDIAL layer of artery- commonly congenital
- happens at areas of BIFURCATION
- Sudden/ severe HA
- Meningisus Triad
Meninngismus Triad
Photophobia, NV, Stiff neck
most commonly found in circle of willis
saccular / berry aneurisms
vasospasm managed by keeping blood volume and pressure at NORMAL TO HIGH levels
Ca++ Channel Blockers
Aneurisms
Failure of capillary system to develop
arterial blood shunted
venous system progressively enlarges r/t high pressure
SEIURES/ nerologic dysfunction
AVM
surgical removal, gamma knife, streotactic radiosurgery, irradiation, glue embolism
AVM
commonly associated with bacterial infections
meningitis
usually viral
encephalitis
nasopharynx entry point
meningitis
secondary problem = accumulation of neutrophils and degranulation
Meningitis -
destroys brain tissue, bacteria, nerves and blood vessels
NEUTROPHILS degranulation
LP - neutrophils, LOW glucose, bacteria, protein ELEVATED
Meningitis
NEUTROPHILS cause vasculitis and clotting leading to cerebral infarcts
meningitis
respiratory tracts, GI tract, inoculation by insects and animal bites such as rabies
entry point fro encephalitis
attacks arachnid membrane and CSF
encephalitis
CYTOKINES and MACROPHAGES cause vascular and tissue injury cells and blood vessels
encephalitis
pus with neutrophils and pyogenic bacteria
brain abcess
infected core of NEUTROPHIL and TISSUE DEBRIS
brain abcess
PERIFOCAL edema with proliferation of ASTROCYTES
brain abcess
LIQIFIED core and fibrous gliosis(dark ring)
brain abcess