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Physiology II > Neuropathophysiology > Flashcards

Flashcards in Neuropathophysiology Deck (64)
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1
Q

What are some of the areas through which the brain may herniate?

A

fibrous structures separating lobes of the brain, foramen magnum

2
Q

How is CPP calculated?

A

MAP - (ICP + CVP)

3
Q

ICP and CPP are _____ related

A

inversely

4
Q

What are two methods for monitoring ICP?

A

“bolt” method and ventriculostomy

5
Q

What major advantage does a ventriculostomy have over an intracranial bolt?

A

ventriculostomy allows drainage of CSF

6
Q

What is the equation for CMRO2?

A

CMRO2 = CBF x OEF x SaO2

7
Q

When calculating CMRO2, how might SaO2 be determined?

A

Using a cerebral oximeter

8
Q

What is the equation for SjO2?

A

SjO2 = SaO2 - (Oxygen Consumption / Cardiac Output x Hb x 1.39)

9
Q

HTN has what effect on O2 extraction?

A

Increases O2 extraction

10
Q

Where is the trans-cranial doppler placed and why?

A

Across the temporal bones because they are thin

11
Q

How would a vasospasm shown on a transcranial Doppler?

A

the waveform would be blunted

12
Q

What may happen to the arteriole after the rupture of an aneurysm?

A

vasospasm

13
Q

What happens to ICP when the brain herniates?

A

ICP decreases

14
Q

A tumor would have what effect on CMRO2?

A

increase

15
Q

How might chronic HTN affect CPP?

A

CPP should not be affected because the autoregulation curve shifts

16
Q

What is the minimum CPP value to keep a patient at?

A

50mmHg

17
Q

At what MAP and CPP should a head injury patient be kept in?

A

MAP >90mmHg, CPP >70mmHg

18
Q

What are ways to treat elevated ICP?

A

head elevation, hyperventilation, paralysis, diuretics, dexamethasone, CSF drainage, control BP, limit fluids, hypothermia, drugs (Pentothal, propofol, etomidate)

19
Q

When controlling high ICP, what temperature range should the patient be kept at? Why?

A

33-35°C; each degree decrease in temperature decreases CBF 5-7% but below 33°C arrhythmias occur

20
Q

When controlling high ICP, how much should the patient’s head be elevated? Why?

A

30°; above 30° arterial blood flow to the brain is compromised

21
Q

When controlling high ICP, to what SaCO2 should the patient be hyperventilated? Why?

A

25-30mmHg; below this narrows cerebral vasculature too much and compromises blood flow

22
Q

When controlling high ICP, why is important to use NMBD?

A

NMBD limit O2 consumption by skeletal muscles, allowing more for the brain

23
Q

Why would Pentothal, Propofol and etomidate be useful in the treatment of high ICP?

A

They decrease CBF and CMRO2

24
Q

Why would dexamethasone be useful in the treatment of high ICP?

A

Dexamethasone is a steroid that can help reduce swelling

25
Q

Why is it dangerous to drain CSF from the spinal cord when ICP is elevated?

A

Can cause herniation since CSF drops below ICP

26
Q

What types of mass lesions are there?

A

tumor, infection, hematoma, congenital

27
Q

If a small lesion caused respiratory arrest, where was the lesion likely located?

A

near the brainstem (compressing on it?)

28
Q

What are some symptoms of elevated ICP?

A

N/V, headaches, dizzines, memory loss, personality changes, hi BP/bradycardia (Cushing’s Response), papilledema (optic disk swelling), seizures

29
Q

What are some things to look for in a CT scan or MRI when evaluating for brain tumor?

A

Are lateral ventrals smaller than normal? Could brain be injured by trying to remove the tumor? What position will the patient need to be in during surgery?

30
Q

What are things to look for pre-operatively when evaluating a patient with neurological dysfunction?

A

Get CT or MRI scans if available, look for signs of elevated ICP, find out what medications they’re taking, what is baseline neurologic function

31
Q

What is a consideration for a patient on anti-epleptics?

A

these patients may metabolize drugs quicker, especially NMBD

32
Q

Patients with brain tumors are likely to have what electrolyte imbalance?

A

hypokalemia

33
Q

Changes in personality necessitate what?

A

CT scan

34
Q

Number one goal in managing a patient with an intracranial mass lesion?

A

preventing changes in CBF

35
Q

Types of intracranial bleeds?

A

subdural hematoma, epidural hematoma, intraparenchymal hematoma, subarachnoid hemorrhage

36
Q

Paranchyma of brain are made of what?

A

neurons and glial cells

37
Q

Three coverings of the brain?

A

pia, arachnoid, dura mater

38
Q

Layers covering brain from outside in?

A

skull, epidural space, dura mater, subdural space, arachnoid, subarchnoid space, pia mater

39
Q

What are the differences between acute, sub-acute and chronic subdural hematomas?

A

Acute hematoma is still bleeding, sub-acute hematoma stopped bleeding but blood is still present, chronic subdural hematoma stopped bleeding and now blood is breaking down

40
Q

Regarding intracranial bleeds, where are arterial bleeds and venous bleeds generally located?

A

arterial - generally in epidural space, venous - generally in sundural space

41
Q

What is a lucid interval? In what kind of hematomas do they generally occur?

A

Occur with epidural hematomas. Patient is asymptomatic (lucid) following trauma, then when enough blood accumulates, they become comatose.

42
Q

Epidural hematomas are often present with what injury?

A

skull fracture

43
Q

Most common site of epidural hematoma? What artery?

A

temporal bone and middle menningeal artery

44
Q

What is the most common cause of sub-arachnoid hemorrhage not related to trauma?

A

rupture of aneurysm

45
Q

What is an arterial-venous malformation and why is it relevant?

A

An abnormal connection between arteries and veins; they sometimes rupture and cause sub-arachnoid hemorrhage.

46
Q

Age of typicaly patient with intracranial tumor?

A

40-60 y/o

47
Q

What EKG changes are associated with sub-arachnoid hemorrhage?

A

P wave changes, development of U waves, ST elevation or depression, T wave changes, PVC’s

48
Q

How might a ruptured aneurysm cause hydroencephalus?

A

Blood getting into the 4th ventricle then clotting, causing an accumulation of CSF

49
Q

Most common arteries associated with intracranial aneurysms?

A

Internal carotid/posterier communicating bifurcation (30-35%); anterior communicating artery (30-35%); middle cerebral artery (20%)

50
Q

What could happen to an aneurysm when MAP gets too high or low?

A

too high - rupture, too low - spasm or hypoperfusion

51
Q

What is SIADH? What does it lead to?

A

Syndrome of inappropriate antidiuretic hormone (seen in 1/3 pts w/ aneurysmal rupture); leads to hyponatremia/hyperkalemia

52
Q

General treatment for vasospasm?

A

“three H’s” - hypervolemia, hypertension, hemodilution (makes blood less viscous so it can flow through vessels easier)

53
Q

What is the incidence of venous air embolism with sitting craniotomies?

A

20-40%!

54
Q

How does venous air embolism present?

A

Decrease in ETCO2, HoTn, coronary ischemia

55
Q

What is the treatment for venous air embolism?

A

turn off N2O, increase PEEP, head down and to right side, flood field with saline, bilateral IJ compression, aspirate entrained air

56
Q

What is the purpose of bilateral IJ compression when treating venous air embolism?

A

To stop air from entering venous circulation

57
Q

What is the purpose of increasing PEEP when treating venous air embolism?

A

To increase CVP

58
Q

Apply 1-6 that corresponds with the Glasgow coma scale for “best motor response:” (a) flexion to pain (b) obeys verbal commands (c) localizes pain (d) no response (e) withdraws to pain (f) extension to pain

A

1 - d, 2 - f, 3 - a, 4 - e, 5 - c, 6 - b

59
Q

What is a normal Glasgow coma scale value?

A

15

60
Q

Patients with a Glasgow coma scale below ____ are often intubated.

A

6-7

61
Q

What is a countrecoup injury?

A

An injury that occurs on the side of the brain opposite that which was impacted (occurs when brain bounces back in skull).

62
Q

Why might a patient with a head injury have HoTN?

A

bleeding from coup or countrecoup injury

63
Q

What is a distracting injury?

A

An injury that distracts a patient from another injury they have

64
Q

What head injury is associated with hyponatremia?

A

Aneurysm and SIADH