Basic - Neuro Flashcards

1
Q

When do you need to be careful administering Succinylcholine to patients who suffered burns?

A

Generally AFTER the first 24 hours - 2 years
- at that point, significant upregulation of nicotinic ACh receptors will occur

*same with pts with stroke and spinal cord injuries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Multiple sclerosis

  • ACh receptors (up/downregulated)
  • Depolarizing muscle relaxant
  • Nondepolarizing muscle relaxant
A

ACh receptors: Upregulated

Depolarizing muscle relaxant:
Careful, especially if flaccidity or spasticity

Nondepolarizing muscle relaxant:
May be more resistant or sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Conditions that cause an upregulation of ACh receptors

A
  1. MS
  2. Burns
  3. Stroke
  4. Spinal cord injury
  5. GBS
  6. Prolonged immobility
  7. Muscular dystrophies
  8. Prolonged use of NMB

*can cause an exaggerated increase in K+ after giving Sux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Lambert eaton syndrome

  • disorder
  • Depolarizing muscle relaxant
  • Nondepolarizing muscle relaxant
A

prejunctional Ca2+ antibodies

Depolarizing muscle relaxant:
more sensitive

Nondepolarizing muscle relaxant:
more sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Lambert eaton syndrome

  • disorder
  • Depolarizing muscle relaxant
  • Nondepolarizing muscle relaxant
A

ACh receptor:
- downregulation

Depolarizing muscle relaxant (sux):
more resistant

Nondepolarizing muscle relaxant (roc):
more sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Myasthenia gravis

  • disorder
  • Depolarizing muscle relaxant
  • Nondepolarizing muscle relaxant
A

ACh receptor:
- downregulation

Depolarizing muscle relaxant (sux):
more resistant

Nondepolarizing muscle relaxant (roc):
more sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
How do barbiturates affect :
ICP:
Cerebral blood flow: 
Cerebral autoregulation:
CMRO2:
A

ICP: Decrease
Cerebral blood flow: Decrease (dose dependent)
CMRO2: Decrease (dose dependent)
Cerebral autoregulation: Unaffected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Treatment for extrapyramidal symptoms or acute dystonic reactions?

A
  1. Anticholinergics
    - diphenhydramine (both anticholinergic and antihistamine)
  2. BDZ
  3. BB

*EPS: abnl movement when cholinergic-dopaminergic balance is off

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

________ on EEG is the goal target of reducing CMRO2 during an open cerebral aneurysm clipping

A

Burst suppression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the upregulation of postjunctional ACh receptors due to?

What risk does this pose?

A

Injury to nerves that cause decreased release of ACh or denervation or lack of ACh stimulus to the post-junctional receptor

hyperkalemia induced cardiac arrest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Cushing’s triad

A
  1. HTN
  2. Bradycardia
  3. Respiratory changes

= ominous sx of serious head injury -> urgent intubation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is mannitol used for in neurosurgery?

A

osmotic diuretic -> quickly decrease ICP
- however, you NEED an intact BBB or else mannitol will raise brain osmolality, increase cerebral volume and risk herniation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is nitroglycerin not recommended in pts with head trauma if they are hypertensive?

A

Cerebral vasodilator -> may further raise ICP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can cross the BBB

A

Small lipophilic molecules

  • oxygen
  • CO2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Treatment for elevated ICP intraop

A
hypertonic saline
diuretics
mannitol
- draw fluid back across the BBB in hopes of decreasing the edema
- however, you NEED an intact BBB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Effect of acute vs chronic use of phenytoin on nondepolarizing NMB

A

Acute:
- Potentiates blockade
(acute reduction in ACh release - less competitive inhibition)

Chronic:
- Increases resistance to blockade (ED95)
- Decreases duration of blockade
(increased postjunctional ACh receptor density - more receptors to block. and decreased sensitivity at the receptor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the ED95 in neuromuscular blocking drugs?

A

dose required to achieve desired effect in 95% of population

18
Q

Effect of phenytoin use on depolarizing NMB (succinylcholine)

A

Prolonged d/t upregulation in ACh receptors - higher risk of hyperK

Upregulation: denervation or lack of ACh stimulus to the post-junctional receptor

19
Q

Post op vision loss secondary to ANTERIOR ischemic neuropathy (AION) is most likely to occur after which type of surgery?

A

Cardiac surgery

*cardiac sx is done on the anterior = AION
posterior spine sx are done on the posterior = PION

20
Q

Post op vision loss secondary to POSTERIOR ischemic neuropathy (PION) is most likely to occur after which type of surgery?

A

posterior spine surgery

anterior ischemic optic neuropathy more common periop cause of vision blindness than posterior

21
Q

Decreasing a pts PaCO2 by 1mmHg will decrease CBF by ____

A

1mL/100g/min

22
Q

Pathway for eccrine sweat gland innervation (located all over the body except lips, and tip of penis and clit)

A

SYMPathetic preganglionic -> nicotinic receptor -> SYMPathetic postganglionic -> muscarinic receptor

23
Q

Pathway for apocrine sweat gland innervation (located in armpit and perianal areas)

A

PARAsympathetic preganglionic -> nicotinic receptor -> PARAsympathetic postganglionic -> muscarinic receptor

24
Q

_____ agents interfere with the sweating mechanism, which may lead to temp increases (esp child with fever)

A

Anticholinergic agents

- include in differential

25
In pts with methemoglobinemia (toxic side effect of benzocaine admin), the only value that significantly changes on ABG is ____
PaO2 - partial pressure of arterial oxygen -
26
What is methemoglobinemia? *occurs after exposure to substances that oxidize hgb faster than methemoglobin reductase can reduce it
Altered state of hgb where the FERROUS (Fe2+) form of heme is oxidized to the FERRIC form (Fe3+) - cannot bind oxygen
27
What can cause methemoglobinemia?
* occurs after exposure to substances that oxidize hgb faster than methemoglobin reductase can reduce it - prilocaine - benzocaine - abx: dapsone, sulfonamides, trimetoprim - metoclopramide - nitrates / nitrites
28
on ABG, which value is NOT directly measured, but calculated based on the assumption that ALL hgb is normal?
SaO2 | - Can be falsely elevated in methemoglobinemia
29
How many days of immobility leads pts to have increased risk of hyperkalemia with depolarizing muscle relaxants?
> 16 days
30
The TOF of a nerve in a paralyzed extremity is ______
exaggerated | - production of extrajunctional ACh receptors in affected muscles -> increase response w/ stim
31
CMRO2 and CBF decrease ___% for every 1C decrease in temperature
6%
32
Increasing PaCO2 from 40-60 mmHg will cause an (increase/decrease) in CBF approximately __%
increase 60%
33
CBF remains unchanged within the autoregulatory range of MAP ____ and PaO2 ____
MAP 50-150mmHg PaO2 >50mmHg
34
How do you calculate the diff in blood pressure in 2 different sites?
Height (cm) x 0.74 Subtract this value from the systolic and diastolic value at the heart * mneumonic: - pH = Pressure height - pH 15 20 = pressure 15 = height 20 cm
35
Tetanus prevents neurotransmitter release (glycine and GABA) from ____ in the ____
inhibitory neurons - inhibition of inhibitory neurons -> increased muscle contractions Spinal cord
36
Botulism prevents neurotransmitter release (ACh) from ____ at the ____
nerves neuromuscular junction
37
What illicit drug is a risk factor for tetanus contraction?
Heroin
38
Neurogenic shock following acute high spinal cord injuries is associated with severe bradycardia and hypotension from _______
unopposed vagal or parasympathetic activity and loss of cardiac accelerator fibers (if injury is above T1-T4)
39
Why would Pts with acute spinal cord injury become bradycardic during intubation?
Stimulation usually occurs above the level of spinal cord injury. Nerve transmission is unable ot descend and activate the thoracic sympathetic chain at T1-T4
40
Why would Pts with acute spinal cord injury present with paradoxical shallow respirations?
implies level of injury is between C4-C7 | - C3, C4, C5 keeps the diaphragm alive
41
Autonomic hyperreflexia beings ___ weeks following acute spinal injury
2-3 weeks
42
Etomidate and ketamine (Increases/decreases) amplitude of Somatosensory evoked potential stimulus (SSEP)
increases