Vertigo

Front 1

Imagine a line that goes posteriorly and diagonally to just behind the left ear. The direction traced out by this line is most similar to the alignment of which semicircular canal?
left anterior
left lateral
left posterior

Back 1

left posterior (vector points from one ear to the contralateral eye)

Front 2

Fluid in the _______ of the semicircular canal deflects the ______ during rotational motion of the head.

Back 2

Fluid in the _ampulla_ of the semicircular canal deflects the _cupula_ during rotational motion of the head.

Front 3

Describe the neuronal pathway involved in the VOR.

Which part of the pathway is most susceptible to damage?

Back 3

1. inner ear sensory info travels on CN 8 to the ipsilateral vestibular nuclei in the brainsteam
2. Vestibular nuclei relays info to bilateral eye nuclei (CN nuclei 6 and 3)
3. Eye nuclei innervate medial and lateral rectus muscles to execute VOR.

The brainstem (vestibular or eye) nuclei are most likely to be damaged (neurological problem).

Front 4

Linear acceleration is detected in the horizontal and verticle directions by the ________ and ________, respectively, maculas of the otolith organ.

Back 4

Linear acceleration is detected in the horizontal and verticle directions by the _utricle_ and _saccule_, respectively, maculas of the otolith organ.

Front 5

What is the easiest way to isolate and test the vestibulospinal reflex?

Back 5

Have patient stand on foam mat (knock out proprioception) while blindfolded (knock out VOR) and observe balance.

Front 6

The tests used to diagnose a "dizzy" patient are _specific or sensitive?_; the tests can be used to rule ____ a specific diagnosis.

Back 6

specific tests rule in diagnoses because they err on the side of giving a negative result (most people who don't have the disease get a negative result, but plenty of people who have it get a negative result as well).

Front 7

How can you tell if "vertigo" is caused by the inner ear (versus CNS)?

Back 7

Vertigo of peripheral origin, signs:
-severe
-sudden onset
-NO disturbance of consciousness
-always nystagmus with vertigo
-autonomic symptoms (i.e. paleness)
-tinnitus (possible)
-Deafness (possible)
-influenced by head position

Front 8

Nystagmus problem: a lesion in the inner ear will usually be coupled with a (contra or ipsi?)lateral beat nystagmus?

Back 8

Nystagmus problem: a lesion in the inner ear will usually be coupled with a contralateral beat nystagmus?

Front 9

A patient's vision is blocked.
a) nystagmus appears: where is the problem (generally?)
b) nystagmus disappears: where is the problem (generally?)

Back 9

a) peripheral (inner ear)
b) central (ocular nuclei)

Front 10

If a patient looks one way while their eyes beat the other way, this is a ______ nystagmus. It is brought on my chemical toxicity, most often ______.

Back 10

Gaze, EtOH

Front 11

A problem with smooth pursuit indicates an _inner ear or central_ problem.

Back 11

central problem

Front 12

Quickly switching from objects in opposite fields tests the patient's saccade ability; asymmetric eye movements indicate _______.

Back 12

indicate a central problem, usually demyelinating (could be multiple sclerosis)

Front 13

Headthrust test: how do you do it, why must it be quick, and how do you tell if there is a problem

Back 13

Quickly turn head to one side while patient fixates on a target; must be quick to inhibit input from the contralateral side; if the patient's eye follows with the turn instead of keeping focus on the target, there is a lesion on the side to which the head was turned.

Front 14

Headshake test relies on continuous information coming in from both sides; if there is a deficit on the right side, the patient's eyes will beat toward the _____ after the shaking is over.

Back 14

beat toward left (side with lesion contributes less information)

Front 15

Dramatically reduced ability to read while your head is shaking indicates impaired VOR due to a (central or inner ear) probelm.

Back 15

inner ear problem

Front 16

Vertigo accompanied with another symptom (i.e. headache) and unilateral hearing deficit are both indications for _______

Back 16

MRI/CT imaging

Front 17

BPV, the most common cause of vertigo, is due to freely moving calcium stones in the ______ semicircular canal.

Back 17

posterior

Front 18

The most common diagnoses...

Back 18

BPV
Meniere's Disease (excess fluid)
Vestibular neuritis
migraine-related

Front 19

Explain how inflammation can decrease a local anesthetic's ability to enter the cell.

Back 19

Inflammation can lower extracellular pH; LA (a weak base) remains protonated longer and cannot easily enter cell.

Front 20

List the three categories of neuron size and their respective sensitivities to LA.

Back 20

small: Adelta (pain) and C (temp/sympathetic sensory) fibers; most vulnerable

medium: B (sympathetic preganglionic), less vulnerable

large: A (proprioception, motor, touch/pressure), least vulnerable

Front 21

All things equal, how do the following affect a fiber's sensitivity to LA:
-position in nerve
-frequency of activity
-Myelination
-Size

Back 21

-position in nerve: increases with greater eccentricity
-frequency of activity: increases with frequency
-Myelination: increases with more myelination
-Size: increases with decreasing size

Front 22

List the determining factors for a LA's potency, onset of action, and duration of action.

Back 22

Potency: hydrophobicity
Onset: hydrophobicity, pKa
Duration: hydrophobicity, vascular access (washout), protein binding (extends life)

Front 23

Toxic effects on excitable cells stemming from LA overdose, in order of likelyhood of occuring:

Back 23

most likely: nervous system (oral numbness, tinnitus, drowsiness)
2nd most likely: cardiac depression (conductance, contractility, pulse all decrease, plus arrythmias)

Front 24

Metabolism difference b/w aminoesters and aminoamides

Back 24

aminoesters: plasma esterases; PABA metabolite (common allergy)
aminoamide: hepatic metabolism

Front 25

treatment for LA toxicity:

Back 25

maintain airway

drugs: barbituates/sedatives to prevent seizures; atropine to reduce PS drive; epinephrine for arrythmia

also new treatment: lipid emulsion to draw LA away from site of action

Front 26

allergic considerations with LAs

Back 26

aminoesters have problems with allergies (metabolite PABA + drug preservative)

Front 27

List the following toxicities associated with these specific agents:

Back 27

Prilocaine: methemoglobinemia (methylated hemoglobin, can't unload O2)
Bupivicaine/etidocaine: cardiac arrythmias
Benzocaine/Procaine: PABA metabolite (allergy)

Front 28

non IV LA:
topical

main concern:

Back 28

don't want to create a drug reservoir (contains prilocaine, watch out for methemoglobinemia)

Front 29

non IV LA:
subcutaneous/subdermal
which drugs?
concern?

Back 29

usually lidocaine, Bupivicaine or Ropivicaine for longer duration
concern = pain upon administering (give w/ baking soda to decrease sting)

Front 30

LA Block technique: Bier
why?
how?

Back 30

Bier block
why = anesthetize an arm
how = exsanguinate limb w/ constrictions, inject LA, wait 30 minutes for protein binding to occur, remove constrictions

Front 31

LA Block technique: plexus
why?
how?

Back 31

plexus block
why = desensitize an entire sensory area
how = hit any plexus (digit, intercostal, femoral, popliteal)

Front 32

LA Block technique: neuraxial
what are the 2 routes?
what are the differences?

Back 32

neuraxial block
spinal and epidural
spinal = rapid, dermatome-based, intrathecal injection
epidural = slower, patchy distributions, requires higher [drug]

Front 33

epinephrine and LA: what's the connection?

Back 33

epinephrine can vasoconstrict (preventing washout); epinephrine also serves as an indicator for accidental arterial injection (tachycardia will occur)