Normal Neurophysiology

Question 1

Name the cortical lobes of the brain and where they are located

Answer 1

frontal (front), parietal (top, back), occipital (back), temporal (side)

Question 2

What is a normal cerebral blood flow?

Answer 2

50cc/100gm/min

Question 3

The brain receives what percent of cardiac output?

Answer 3

15-20%

Question 4

What percent of body mass does the brain account for?

Answer 4

2%

Question 5

Increased cerebral metabolic activity causes a _____ in CBF

Answer 5

Increase

Question 6

A CBF of what would result in cognitive impairment? Isoelectric EEG?

Answer 6

< 20 – 25 ml/100 g/min; < 15 - 20 ml/100 g/min

Question 7

If CBF to one side of the brain is diminished (such as from an atherosclerotic artery), it would be expected that the OEF in the diminished area would be (decreased/increased)?

Answer 7

Increased. A higher oxygen extraction fraction would be needed to account for diminished blood supply.

Question 8

What are the five determinants of CBF?

Answer 8

CMRO2, PaO2, PaCO2, temperature, drugs

Question 9

What are some of the roles of the brainstem?

Answer 9

respiration, temperature regulation, metabolism

Question 10

What is the main role of the cerebellum?

Answer 10

coordination of movement

Question 11

Cortical vision takes place in what lobe?

Answer 11

occipital

Question 12

Hearing is a function of what lobe?

Answer 12

temporal

Question 13

Which arteries supply blood to the circle of Willis?

Answer 13

basilar artery, internal carotid arteries, and middle cerebral arteries

Question 14

How long does it take for the brain to be without O2 to be irreversibly damaged?

Answer 14

Roughly 4 minutes

Question 15

What happens to blood flow in the circle of Willis if one of the arteries supplying blood is occluded?

Answer 15

Blood will circulate in the direction opposite of how it was circulating before

Question 16

What are two general ways to fix a cerebral aneurysm?

Answer 16

Surgically (clipping) or by invasive radiology (usually involves placing a catheter or coil to stop blood flow to the aneurysm)

Question 17

Which artery(ies) supply blood to the frontal lobes?

Answer 17

Anterior cerebral arteries

Question 18

Which artery(ies) supply blood to the lateral lobes?

Answer 18

middle cerebral arteries

Question 19

Which artery(ies) supply blood to the cerebellum and occipital lobes?

Answer 19

posterior cerebral arteries

Question 20

What is watershed?

Answer 20

Watershed areas are the most distal terminal areas of perfusion

Question 21

Which areas of the brain are most susceptible to infarction?

Answer 21

Interior watershed portions

Question 22

Where do aneurysms generally occur?

Answer 22

At bifurcations

Question 23

Autoregulation couples CBF with what?

Answer 23

CMRO2

Question 24

CBF changes how much per mmHg change in CO2 (not H+)?

Answer 24

1-2 ml/100g/min

Question 25

O2 extraction fraction can be observed with what monitor?

Answer 25

PET scan

Question 26

Normal O2 extraction of brain?

Answer 26

25-30% (same as with other organs)

Question 27

Temperature and CMR are _____ related?

Answer 27

directly

Question 28

Hypoxia causes arteries in the brain to _____.

Answer 28

dilate

Question 29

Hypercarbia causes vessels in the brain to _____.

Answer 29

dilate

Question 30

Metabolic alkalosis leads to a(n) ______ in CBF.

Answer 30

decrease

Question 31

CBF changes by how much for every 1°C?

Answer 31

5-7%

Question 32

At what temperature might a patient be isoelectric on an EEG?

Answer 32

20-25°C

Question 33

What is the relationship between volatiles and CBF? Why?

Answer 33

Volatiles increase CBF because they cause vasodilation

Question 34

What is the typical relationship between anesthetic drugs/volatiles and CMRO2/CBF?

Answer 34

anesthetic drugs/volatiles generally decrease CMRO2 and increase CBF

Question 35

Which volatile agent increases CMRO2?

Answer 35

N2O

Question 36

Which drugs decreases CBF?

Answer 36

barbiturates, propofol, etomidate

Question 37

Which drug increases CBF and has no effect on CMRO2?

Answer 37

Ketamine

Question 38

Which drug causes a transient increase in CBF?

Answer 38

Sux

Question 39

CBF autoregulation occurs most successfully across a MAP range of what?

Answer 39

50-150mmHg

Question 40

Why is it important to keep people with chronic HTN within 10-20% of baseline MAP?

Answer 40

Autoregulation curve shifts over time with HTN. Allowing blood pressure to drop too low may take it out of the CBF autoregulation range and CBF would drop dramatically (see CBF autoregulation curve).

Question 41

What is the equation for CPP?

Answer 41

CPP = MAP - ICP or CPP = (SBP - CVP) - ICP

Question 42

What is a normal MAP range? What is a normal ICP range?

Answer 42

MAP 70-110mmHg; ICP 7-15mmHg

Question 43

What is the minimum value CPP should be kept at?

Answer 43

50mmHg

Question 44

Relative percentages of intracranial components? (brain, blood, CSF)

Answer 44

brain 80%, blood 12%, CSF 8%

Question 45

What is the Monroe-Kelly Doctrine?

Answer 45

"The total volume of intracranial contents must remain stable." i.e. skull is a closed space and if one of the components increases, another must decrease

Question 46

Where is CSF produced and stored?

Answer 46

In the ventricular system (actually produced by choroid plexus and ependymal cells within ventricles).

Question 47

Which portion of the ventricles has openings which allow CSF to bath the brain?

Answer 47

the 4th ventricle

Question 48

What is the condition that occurs when there is a large excess of CSF in the skull?

Answer 48

hydroencephalus

Question 49

What is a typical rate of CSF production?

Answer 49

21ml/hr (500ml/day)

Question 50

What happens to CSF?

Answer 50

It gets reabsorbed by the body