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Neuropathology > Eye Movements and Dizziness > Flashcards

Eye Movements and Dizziness Flashcards

1
Q

Vertigo

def

A

illusion of movement: rotation, translation or tilt

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2
Q

Dysequilibrium

def

A

imbalance while standing or walking; ataxia, proprioceptive or kinesthetic dysfunction, motor dysfunction

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3
Q

Presyncope

def

A

Lightheadedness, graying out of vision

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4
Q

Psychologic dizziness

types

A

Confusion: poor concentration, agitation
Giddiness: elation, excitement
Derealization: depersonalization, déjà vu, detachment

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5
Q

Functional classes of human eye movements

Visual fixation

def

A

Holds an image of a stationary object on the fovea when the head
is stationary

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6
Q

Functional classes of human eye movements

Vestibular

def

A

Holds images of the seen world steady on the retina during brief head movements

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7
Q

Functional classes of human eye movements

Optokinetic

def

A

holds images of the seen world steady on the retina during sustained head rotation

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8
Q

Functional classes of human eye movements

Smooth pursuit

def

A

holds the image of a moving target steady on the retina

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9
Q

Functional classes of human eye movements

Nystagmus quick phases

A

Reset the eyes during prolonged rotation and direct gaze towards the oncoming visual scene

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10
Q

Functional classes of human eye movements

Saccades

def

A

Bring images of objects of interest onto the fovea

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11
Q

Functional classes of human eye movements

Vergence

def

A

Move the eyes in opposite directions so that images of a single object are simultaneously placed on both foveae

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12
Q

Static eye movements

List/fun

A

(1) Saccade- To acquire target
(2) Vergence- To align eyes on target
(3) Fixation- To hold target

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13
Q

Diplopia is a problem of…

A

Diplopia, or double vision, is a problem of static eye movements: Failure to align eyes on target and keep them there

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14
Q

Testing static eye movements

Red glass or Maddox rod

A

(1) The red lens over one eye allows determination of which image comes from each eye. The ribbed lens of the Maddox rod additionally eliminates normal image fusion by vergence.
(2) The patient is asked to look at a light and describe what is seen in each of the 9 directions of gaze, and the result is diagrammed in a tic-tac-toe figure as shown.
(3) Looking toward the weak muscle gives the greatest divergence.
(4) The weak muscle may be a result of a cranial nerve deficit, or due to a problem with the connections between nuclei, as in internuclear ophthalmoplegia, where there is an interruption in the medial longitudinal fasciculus connecting the cranial nerve VI nucleus with the cranial nerve III nucleus.

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15
Q

Dynamic eye movements

list

A

(1) Vestibular reflex
(2) Optokinetic movement
(3) Nystagmus quick phases

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16
Q

Anatomic parts of vestibular apparatus

A

A) Saccule and utricle are translational accelerometers

B) Semi-circular canals (SCCare rotational accelerometers)

17
Q

Parts of vestibular apparatus

Look it up

A

Do it

18
Q

Functions of VOR

A

A) Gain and phase: gain is the degree to which head movement moves the eyes, phase refers to how quickly the response occurs

19
Q

Oscillopsia

def

A

Loss of VOR

20
Q

Connections for lateral eye movements

A

Excitation at the semicircular canal stimulates the medial vestibular nucleus which stimulates the contralateral sixth nerve nucleus which stimulates the ipsilateral 3rd nerve nucleus via the MLF.

21
Q

Bedside tests of vestibular function

list

A

Hallpike-Dix maneuver

Baranys Caloric test

Suppression of fixation

Past pointing

22
Q

Hallpike-Dix Maneuver

What does it provoke

A

Provokes severe nystagmus in BPPV or milder nystagmus in other peripheral lesions

23
Q

Hallpike-Dix Maneuver

How is it done

A

(1) Have patient turn head 45o to one side and extend neck- this puts the posterior canal on that side in the plane of rotation
(2) Move patient quickly from sitting to lying, letting head hang below horzontal plane- observe for nystagmus for one minute
(3) Move patient quickly back to sitting- observe again for nystagmus for one minute
(4) Repeat with head turned the other way to test the posterior canal on the other side

24
Q

Caloric Test

How is it done

A

COWS CUWD

a. Cold water -> nystagmus beating to the opposite side (slow phase toward the ear being tested)
b. Warm water -> nystagmus beating to the same side (slow phase away from the ear being tested)
c. Cold water in both ears -> nystagmus beating upward (slow phase downward)
d. Warm water in both ears -> nystagmus beating downward (slow phase upward)

25
Q

Suppression of fixation

mech

A

Suppression of fixation: brings out nystagmus

(1)Use Frenzel goggles or ophthalmoscope while covering the other eye, so patient can keep gaze steady by focusing on a target

26
Q

Past pointing

mech

A

(1) Hold one arm extended forwards, swing up to vertical then back down to a target, repeat
(2) Continue repeating this motion with eyes closed. Vertigo will cause drift away from the target.

27
Q

Peripheral vs central vertigo (chart)

Nystagmus direction/fixation/gaze

A

Nystagmus direction
Peripheral: Usually mixed (horizontal & rotational)
Central: Usually a single direction

Fixation
Peripheral: Usually suppresses nystagmus
Central:Usually does not suppress nystagmus

Gaze
Peripheral: Nystagmus increases with gaze toward the direction of the quick phase
Central: No change or reverses direction

28
Q

Peripheral vs central vertigo (chart)

Calorics/balance/Assoc with

A

Calorics
Peripheral: Little change
Central: Increases

Balance
Peripheral: Mild defect, poor tandem, + past-pointing, (-) Romberg
Central: Severe defects, unable to tandem, +/- past-pointing, + Romberg

Assoc with
Peripheral: May be assoc with hearing loss or tinnitus
Central: Usually no hearing loss or tinnitus, may be assoc with brainstem or cerebellar signs

29
Q

Episodic Dizziness

Time/chars/dx/rx

1 minute or less

A

(1) Benign paroxysmal positional vertigo (BPPV)
(2) Etiology: otolith or other debris is loose in semicircular canals (usually posterior)
(3) Dx: Positive Hallpike-Dix maneuver
(4) Rx: Epley’s or Semont’s maneuver

30
Q

Modified epley’s maneuver (pg. 369)

Mech/alternative

A

(i) One minute to slowly change positions, four minutes in each postion
(ii) Debris (otoconia) falls into saccule
(iii) Patient then wears a soft collar, no bending, sleeps sitting up for two days while debris adheres, resorbs

Seemont’s Maneuver: not shown but similar, can try if Epley’s fails

31
Q

Episodic Dizziness

1 hour or less

list/dx/rx

A

(1) Transient ishemic attack (TIA)
a. Dx: Cerebrovascular & cardiac studies
b. Rx: Reduce risk factors, antiplatelet drugs, CEA

(2) Migraine
a. Dx: International Headache Society criteria
b. Rx: Diet, Sumatriptan, other medications

(3) Panic Attacks
a. Dx: DSM-III R criteria
b. Rx: Benzodiazepines, tricyclics

32
Q

Episodic Dizziness

Hours to days

List/dx/rx

A

Meniere’s Syndrome

a. Dx: fluctuating hearing loss, low frequency sensorineural hearing loss, tinnitus
b. Rx: Low salt diet, no caffeine, Diamox, surgery

33
Q

Vestibular Suppressants

list

Antivertiginous
Antiemetics
Other

A

Antivertiginous (sedation):
Diazepam
Droperidol

Antiemetics:
Promethazine
Prochlorperazine

Other:
Meclizine
Scopolamine

34
Q

Management of acute vertigo

Day 1-3

A

(1) Vestibular suppressants
(2) Bed rest
(3) Hospitalize if dehydrated or if central defect is suspected
(4) Laboratory tests: FTA (fluorescent treponemal antigen for syphilis), ESR (erythrocyte sedimentation rate), rheumatoid factor, ANA (anti-nuclear antibodies for systemic lupus)
(5) MRI

35
Q

Management of Acute vertigo

subacute

More than 3 days

A

(1) Stop vestibular suppressants!
(2) Begin vestibular exercises
(3) Laboratory tests: Audiogram, Caloric testing, Rotary chair test

Neuropathology (29 decks)

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