Neuro Pathophysiology Flashcards
What role does the frontal lobe play?
Strong role in emotions
What is fMRI? What can you see on it?
function magnetic resonance imaging. You can see how neurons are passing info from neuron to neuron.
What role does the brain stem play?
Basic functioning for human existence; where respiratory center, sleep/wake cycle and temp regulation
What is the role of the cerebellum?
Regulation/coordination of movement
What role does the limbic system have?
Role in emotions
Which structures have a role in endocrine function?
Pituitary and hypothalamus
Which structures play a role in memory and emotional processing?
Hippocampus and amygdala
Which structure triggers “flight or fight”?
Amygdala
Which lobes of the brain make up the “higher order” cortex?
Temporal lobe, occipital lobe, parietal lobe, frontal lobe
What portion of the brain does the Circle of Willis supply blood to?
Perfuses the entire brain
Two vertebral arteries (directly off aortic arch) join together to make the ____.
Basilar artery
Which vascular structures are the main blood flow to the brain, directly off aorta?
Internal carotid arteries and vertebral arteries
Which arteries connect the cerebral arteries?
Communicating arteries
Which arteries perfuse the temporal and parietal lobes?
Middle cerebral arteries
Which arteries perfuse the frontal lobe?
Anterior cerebral arteries
Which arteries provide perfusion to cerebellum and occipital areas?
Posterior cerebral arteries
What are watershed areas?
Most distal area of perfusion; between 2 terminal arteries; most at risk during times of poor perfusion
Where are aneurysms likely to develop?
Bifurcating point
T or F. You can regenerate neurons and connections between them.
False. You can only regenerate connections.
What is the normal cerebral blood flow?
50cc/100 g/min
What percentage of CO does the brain receive?
15 - 20%
What is the range of blood flow the brain can receive?
10 - 300 ml/100 g/min
What are the results of CBF < 20-25 ml/100 g/min?
Cognitive impairment
What are the results of CBF < 15-20 ml/100 g/min?
Isoelectric EEG
What type of imaging can you visualize OEF?
PET Scan
What is OEF of brain?
25-30%
If cerebral blood flow goes dow, OEF goes ___.
Up
What is hyperemic response?
Increased blood flow after restored blood flow (arteries are dilated)
____ is tightly coupled to ____.
CBF, CMR
When temperature goes, enzymatic activity goes __ and so does ____ and ____.
up, CMR, and blood flow.
One way to protect the brain:
Cool it (decreased O2 demand)
You measure cerebral metabolic rate with ____.
Calimetry and looking at jugular venous saturation.
What happens when PaO2 is decreased (<60 mm Hg)?
Arterial dilation
What happens when PaCO2 is increased in the brain?
Turns to carbonic acid in interces of brain and vasodilation.
What effect does the decrease in CO2 cause during hyperventilation?
Vasoconstriction; decrease CBF, helpful in decreasing ICP
What is the normal PaCO2 range?
20 - 80 mm Hg
CBF changes _____ per mm Hg change in CO2.
1-2 ml/100 g/min
T or F. CBP changes when a person gets acutely metabolic acidodic.
False
CBF changes ____ % per degree change celsius.
5-7%
At what temperature is your EEG isoelectric?
20 degress
T or F. Volatile agents cause a dose dependent reduction in CMR.
True
T or F. Volatile agents change coupling with CBF.
True
CBF is ___ with higher levels of volatile agent.
higher
T or F. Volatile agents are direct vasodilators.
True
Neurological Properties of NO
- Stimulates CMR
- Increased CBF
- Increases ICP
- Effects minimal with barbs, narcotics, and hypocarbia
5 Neurological Properties of Thiopental (Pentathal)
- Decreased CBF
- Decreased CMO2
- Reactivity to PaCO2 maintained
- Uniform metabolic depression
- Good for protective measures of brain; to put people in coma
4 Neurological Properties of Propofol
- Decreases CBF
- Decreases CMO2
- More prominent depression in cortical tissue (not good for comas)
- Maintained PaCO2 reactivity
6 Neurological Properties of Etomidate
- Reduced CBF
- Reduces CMO2 in a dose dependent manner
- Metabolic depression is not uniform (forebrain)
- Reduces CBF more than CMR (in dogs)
- Low doses can lower seizure threshold
- Myoclonus may be interpreted as seizure activity
5 Neurological Properties of Ketamine
- Increases CBF
- No effect on overall CMO2
- Increases CSF levels by blocking reabsorption
- Not used in neuro regularly
- Increases ICP
Neurological Properties of Succinycholine
-Transient increase in ICP
Which way is the autoregulation curve shifted in patient’s with chronic high BP (untreated)?
To the right
Equation for CPP
CPP = (MAP - CVP) - ICP
What is the normal CPP range?
60 - 80 mm Hg
CPP 25- 40 mm - Hg shows ___ on EEG.
Flatline
At what CPP does a patient have irreversible brain damage?
< 25 mm Hg
What are the skull component volumes/percentages?
Brain TIssue: 1280 cc (80%)
Blood: 192 cc (12%)
CSF: 128 cc (8%)
Total volume: 1600 cc
What is the Monroe-Kellie Doctrine?
The total volume of intracranial contents must remain stable.
What is the normal ICP?
< 15 mm Hg (Usually around 10 mm Hg)
What is hydrocephalus?
When CSF cannot get out and ventricles grow
5 Properties of CSF:
- Protects the brain
- Produced and stored in ventricles
- Produced by choroid plexus (modified ependymal cells in ventricles)
- Produces 21 ml/hr (500 ml/hr)
- Gets recycled (reabsorbed by body)
What are two places the brain can herniate?
Tantoriums or foramena
What is the difference between a Bolt and a Ventriculostomy?
They both measure ICP but a bold only goes into brain. The ventriculostomy catheter goes into the ventricles and you can drain CSF
What happens to waveforms as intracranial pressures increase?
The waveform becomes more blunt/ you lose the waveform.
What is an ominous sign on an ICP monitoring device?
If you go from lost waveforms to regular waveforms suddenly it could mean herniation.
What is are the ways to measure CMRO2?
Inject pt with radioactive glucose and analyze its uptake;
What will CMRO2 be in there is no perfusion to the brain?
0
Equation for CMRO2?
CMRO2 = CBF X OEF X SaO2
Define autoregulation as it pertains to berebral blood flow.
As CMRO2 goes up, so does CBF; if CBF stays constant OEF goes up instead
What are some of the ways to measure cerebral O2 saturation?
Cerebral oximeter; jugular venous bulb oximetry; transcranial saturation
What is equation for jugular venous saturation?
SjO2 = SaO2 - (Oxygen consumption/cardiac output X Hgb X 1.39) [Mixed venous equation]
What is the drawback for using jugular venous bulb oximetry?
Invasive; problem getting blood to brain if there’s intracranial HTN > increased OEF > lower jugular venous blood oximetry
What are transcranial doppler ultrasounds used for?
To look at movement of RBCs; flow and speed; Used on temporal bone (thin) and to screen people after aneurysm rupture to detect vasospasm
What is the first neurological sign a patient is experiencing decreased CPP?
Patient starts to get goofy
What is the normal CPP goal for adequate perfusion?
> 50 mm Hg
What are the MAP and CPP goals for a patient with brain injury?
MAP > 90 mm Hg
CPP > 70 mm Hg
What are the 10 ways to treat elevated ICP?
- Head elevation up to 30 degrees.
- Hyperventilation: CO2 25 - 30 mm Hg
- Hypertension control
- Paralysis
- Pentothal (or bariturate coma)
- Diuretics
- Dexmethasone (helps control leaky vessels)
- CSF Drainage (intracranially)
- Fluid control
- Controlled hypothermia: 33 - 35 degrees celsius (passively)
