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632: Neuroanatomy-Neuroscience > Disorders of the Vestibular and Visual Systems > Flashcards

Disorders of the Vestibular and Visual Systems Flashcards

1
Q

What is vertigo?

A

An illusion of motion

*most common symptom of vestibular system disorder

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2
Q

What does vertigo arise from?

A

a disturbance of spatial orientation in the vestibular cortex

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3
Q

Vestibular disorders may cause ______ nystagmus

A

pathologic

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4
Q

Does pathologic nystagmus fatigue and habituate in periperhal or central disorders?

A

in most peripheral disorders, but not in central disorders

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5
Q

What does a complete lesion affecting receptors or cranial nerves dedicated to that system produce?

A

a total ipsilateral loss of sensory input for the particular system

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6
Q

What does a complete lesion in the retina or optic nerve cause?

A

ipsilateral blindness in the visual system

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7
Q

Do peripheral or central disorders typically cause recurring periods of vertigo and more severe nausea?

A

Peripheral vestibular disorders

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8
Q

What always accompanies peripheral vertigo?

A

nystagmus

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9
Q

What are 2 other symptoms of vestibular disorders?

A
  • diminished hearing

- tinnitus

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10
Q

What are 5 common peripheral vestibular disorders?

A
  • benign paroxysmal positional vertigo (BPPV)
  • vestibular neuritis
  • Ménière’s disease
  • traumatic injury
  • perilymph fistula
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11
Q

What benign paroxysmal positional vertigo (BPPV)?

A

An inner ear disorder that causes acute onset of vertigo and nystagmus

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12
Q

BPPVs are benign meaning….?
Paroxysmal meaning…?
Positional meaning…?

A
  • Benign: Is not malignant.
  • Paroxysmal: Has a sudden onset of a symptom or disease.
  • Positional: Denotes head position as the provoking stimulus.
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13
Q

Rapid change of head position, resulting in vertigo and nystagmus, will subside in less than _ minutes, even if the provoking head position is sustained.

A

2

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14
Q

What are 4 activities that frequently provoke BPPV?

A
  • Getting into or out of bed
  • Bending over to look under a bed
  • Reaching up to retrieve something from a high shelf
  • Turning over in bed
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15
Q

What causes BPPV?

A

the displacement of otoconia from the macula into a semicircular canal

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16
Q

Signs and symptoms of BBPV can be provoked using the _____ maneuver.

A

Hallpike

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17
Q

The displacement of otoconia may occur spontaneously or it may be the result of what?

A

trauma or infection of the vestibular apparatus

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18
Q

What is Vestibular Neuritis?

A

Inflammation of the vestibular nerve

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19
Q

What usually causes Vestibular Neuritis?

A

a virus

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20
Q

What are the symptoms of Vestibular Neuritis?

A
  • dysequilibrium
  • spontaneous nystagmus
  • nausea
  • severe vertigo
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21
Q

Is hearing affected in Vestibular Neuritis?

A

no

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22
Q

What is Ménière Disease?

A

A disease that causes a sensation of fullness in the ear, tinnitus, severe acute vertigo, nausea, vomiting, and hearing loss

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23
Q

What is Ménière Disease associated with?

A

Abnormal fluid pressure in the inner ear

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24
Q

Traumatic injury may cause what 3 things to occur which may alter the vestibular system?

A
  • concussion of the inner ear
  • fractures of the bone surrounding the vestibular apparatus and nerve
  • pressure changes in the inner ear
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25
Q

What is perilymph?

A

fluid in the space between the bone and the membranous labyrinth in the inner ear

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26
Q

A perilymph fistula is the result of what?

A

An opening between the middle and inner ear which allows perilymph to leak from the inner ear into the middle ear

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27
Q

What does a perilymph fistula produce?

A
  • abrupt onset of hearing loss
  • tinnitus
  • vertigo
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28
Q

What is oscillopsia?

A

the subjective sensation of visual objects bouncing when the head is moving or the persons is walking

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29
Q

Oscillopsia tends to occur because normal reflexive adjustments for head movement are _______.

A

decreased

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30
Q

Oscillopsia is the initial complaint of what?

A

Bilateral Lesionsof the Vestibular Nerve

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31
Q

Central Vestibular Disorders are the result of what?

A

damage to the vestibular nuclei or to the connections within the brain

32
Q

Central Vestibular Disorders are most commonly the result of what 4 things?

A
  • ischemia or tumors in the brainstem/cerebellar region (e.g., Wallenberg’s syndrome)
  • cerebellar degeneration
  • multiple sclerosis
  • Arnold-Chiari malformation
33
Q

What may also cause vestibular dysfunction?

A

Migraine headaches

34
Q

What does unilateral vestibular loss cause problems with?

A
  • posture
  • eye movement control
  • nausea
35
Q

Peripheral lesions interfering with otolithic function on one side causes imbalance which produces a tendency to fall _____ the side of the lesion.

A

toward

36
Q

A unilateral lesion affecting the otoliths or the vestibular nuclei may produce what?

A

An ocular tilt reaction

37
Q

What does bilateral vestibular loss eliminate?

A

A person’s internal sense of gravity

38
Q

What must a person with bilateral vestibular loss relay on for spatial orientation?

A

visual and proprioceptive cues

39
Q

IS vertigo present in bilateral vestibular loss? Why or why not?

A

No, because there is no asymmetry of the vestibular information

40
Q

Bilateral loss of semicircular input causes failure of which reflex?

A

VOR

41
Q

When a person with bilateral vestibular loss walks, what happens?

A

the world appears to bounce up and down

42
Q

What is a common symptom of individuals with chronic vestibular dysfunction?

A

stiffness of the neck and shoulders, due to attempting to stabilize the head to lesson vertigo or oscillopsia.

43
Q

Visual losses are clinically described by referring to the “_______________”.

A

“visual field deficit.”

44
Q

What is anposia?

A

Loss of sight in one or both eyes

45
Q

What is hemianopsia?

A

Loss of sight in one half of the visual field

46
Q

What is homonymous hemianopsia?

A

Loss of vision in the left or right visual field of both eyes

47
Q

A lesion of the optic nerve will cause what?

A

loss of vision from the ipsilateral eye

48
Q

A lesion of the optic chiasm will cause what?

A

bitemporal hemianopsia

49
Q

A lesion of the optic tract will cause what?

A

loss of vision from the contralateral visual field of both eyes (homonymous hemianopsia)

50
Q

Describe a person who is cortically blind

A

They have no awareness of any visual information

51
Q

What is blind sight?

A

the ability of an individual who is cortically blind to orient or point to visual objects

52
Q

How can a person who is cortically blind orient their head position?

A

Because the ability to perceive light and dark is vaguely retained in the visual system

53
Q

The ability of a cortically blind person to orient to visual objects is contingent on what?

A

Intact function of the retina and pathways from retina to superior colliculus

54
Q

Abnormalities of eye movement occur with lesions involving what 6 things?

A
  • Cranial nerves that control extraocular muscles
  • Strength of extraocular muscles
  • Medial longitudinal fasciculus
  • Vestibular system
  • Cerebellum
  • Eye fields in the cerebral cortex
55
Q

What are tropia and phoria?

A

deviations of the ability to align the eyes

56
Q

Define tropia

A

the deviation of one eye from a forward gaze when both eyes are open

57
Q

Define phoria

A

the deviation from a forward gaze, apparent only when the person is looking forward with one eye, while the other eye is covered.

58
Q

What is motion sickness?

A

Nausea, headache, anxiety, and vomiting experienced in moving vehicles

59
Q

What may cause motion sickness?

A

A conflict between different types of sensory information or by postural instability.

60
Q

What may cause seasickness?

A

A conflict between visual and vestibular information

61
Q

When a patient reports dizziness what 4 things must the clinician distinguish among?

A
  • Vertigo: illusion of movement (vestibular disorder)
  • Near syncope: feeling of impending faint (cardiovascular)
  • Dysequilibrium: loss of balance (usually neurologic)
  • Light-headedness: inability to concentrate (psychological such as anxiety disorder)
62
Q

What is the most important question to answer if the patient has a vestibular disorder?

A

Whether the lesion is peripherally or centrally located

63
Q

Postural tests are classified as one of what 2 types of tests? Give an example of each

A
  • Static: Romberg’s test

- Dynamic: tilt boards

64
Q

Which coordination test examines lower limb coordination?

A

Tandem walking and the heel-to-shin test

65
Q

What is sensory ataxia characterized by?

A

It is characterized by impaired vibratory and position sense, decreased or lost ankle reflexes, a lack of nystagmus, and a lack of vertigo.

66
Q

What is cerebellar ataxia characterized by?

A

The inability to stand with feet together, regardless of whether the eyes are open or closed. Vertigo and nystagmus may be associated.

67
Q

When is cerebellar ataxia evident?

A

All of the time, regardless of whether the person is standing, sitting, or lying down.

68
Q

When is vestibular ataxia evident?

A

When walking; limb movements are normal when lying down

69
Q

What is sensation testing used for?

A

to localize a lesion

70
Q

What 3 senses are tested during sensation testing?

A

Hearing, proprioception, and vibration

71
Q

What are proprioception and vibration tests used to distinguish between?

A

lesions of the conscious proprioception pathways and vestibular lesions

72
Q

When performing the Hallpike maneuver, if the left ear, rotary nystagmus is _______; if the right ear is affected, rotation is ________.

A

clockwise

counterclockwise

73
Q

What are 5 ways in which Vestibulo-Ocular Reflexes are tested?

A
  • Passive, rapid head thrusts
  • Testing dynamic visual acuity
  • Using a rotating chair
  • Caloric testing
  • Electronystagmography
74
Q

Describe how a caloric test is performed

A

A small amount of cold (30° C) or warm (44° C) water is instilled into the ear canal.

  • In a conscious patient, the mnemonic COWS summarizes the saccadic movements of the eyes: cold opposite, warm same
  • Nausea and vomiting may result from the vestibular action on autonomic function.
75
Q

What is Electronystagmography?

A

a recording of eye movements

76
Q

The ability to direct gaze can be tested by which 3 tests?

A
  • Cover test
  • Cover-uncover test
  • Alternate cover test
77
Q

What are rehab exercises designed to promote?

A

movement retraining, habituation, or substitution to improve function

632: Neuroanatomy-Neuroscience (26 decks)

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