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Neurophysiology > Special Senses: Vision, Hearing and Vestibular > Flashcards

Special Senses: Vision, Hearing and Vestibular Flashcards

1
Q

T/F: There is a greater proportion of our brain devoted to vision than any other sense?

A

TRUE

multiple concurrent visual processes are ongoing continuously like:

  1. conscious perception of visual image info
  2. conventional visual reflexes
  3. saccadic movements
  4. regulation of sleep/wake
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2
Q

A lesion to the optic nerve prior to the optic chiasm would result in what type of visual deficit?

A

blindness in the ipsilateral eye

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3
Q

what are the functional implications to ipsilateral blindness?

A
  1. poor depth perception
  2. small visual field
  3. far peripheral vision is impacted = difficulty with driving and other higher level tasks
  4. potential musculoskeletal issues like pain from positioning to compensate
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4
Q

compression of the optic chiasm would result in what visual defict?

A

binasal hemianopsia = loss of nasal fields bilaterally, temporal fields spared

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5
Q

what are the functional implications of binasal hemianopsia?

A

trouble with near vision and any tasks that utilize that like reading

difficulty concentrating

difficulty with ADLS

**these pts can usually learn to compensate pretty well though

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6
Q

a lesion to the optic chiasm would result in what visual deficit?

A

bitemporal hemianopsia = results in loss of temporal fields, nasal fields spared

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7
Q

bitemporal hemianopsia is commonly seen with what type of injury?

A

pituitary tumors

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8
Q

what are the functional implications of bitemporal hemianopsia?

A

it’s like having horse blinders on!

miss peripheral objects and trip on things

miss doors

common fall risk

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9
Q

what do patients with bitemporal hemianopsia require?

A

prism glasses or other external aids to be safe on their feet

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10
Q

a lesion to the optic tract after the optic chiasm results in what type of visual deficit?

A

homonymous hemianopsia = complete loss in affected region of binocular visual field

Temporal half of R/L visual field + nasal half of L/R visual field

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11
Q

homonymous hemianopsia is common with what type of injury?

A

CVA

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12
Q

what are the functional implications of homonymous hemianopsia?

A

difficulty seeing everything on one side

must teach pt to turn towards the side they are missing

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13
Q

a lesion to the lower division of the optic radiations (in temporal lobe) results in what visual deficit?

A

upper quadrantopia

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14
Q

what are the functional implications for someone with upper quadratanopia?

A

none really!

just mostly annoying to pts but they can function just fine

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15
Q

a lesion to the upper division of the optic radiation (temporal lobe) would result in what visual deficit?

A

lower quadrantanopia

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16
Q

what are the functional implications of lower quadrantanopia?

A

might just be an annoyance and pt can function/adapt just fine

BUT, pts often forget to compensate with this making tripping and falling more common

17
Q

what causes homonymous hemianopia with macular sparring?

A

a lesion to both division of the optic radiations

or a lesion to the visual cortex

18
Q

what are the functional implications to homonymous hemianopsia with maccular sparring?

A

the exact same as homonymous hemianopsia

19
Q

what is the typical cause of monoaural hearing loss?

A

peripheral lesion/damage

cochlear lesion or damage to CN VIII

20
Q

what does having 2 ears help us with?

A

localization of source of sound

21
Q

what are some common causes of acquired hearing loss?

A
  1. acoustic neuroma
  2. meniere’s disease
  3. traumatic brain injury
  4. ototoxicity
  5. presbycusis
22
Q

what are the functional implications of hearing loss?

A

can impact the ability to participate in social settings

but other than that none really/just annoying

23
Q

T/F: if there is acquired hearing loss, vestibular loss/dysfunction is usually not far behind

A

TRUE

24
Q

List the 3 vestibular reflexes

A
  1. Vestibulo-occular reflex (VOR)
  2. Vestibulospinal reflex (VSR)
  3. Vestibulocollic reflex (VCR)
25
Q

what is the VOR?

A

allows us to stabilize gaze during head movements

results in eye movements that equally coutner head movements

26
Q

describe how the VOR would work with L head turning

A

+L semicircular canals → +R abducens and +L occulomotor to move eyes

-R semicircular canals → -L abducens and -R occulomotor

27
Q

Vestibular damage involving the VOR would most likely impact what structures?

A
  1. Central: damage to midbrain and pons
  2. Peripheral: CN VIII, labryinth structures
28
Q

damage to the VOR would result in what impairments?

A
  1. difficulty stabilizing image on retina while head is moving
  2. bilateral vestibular dysfunction
    1. oscillopsia = bouncing vision
  3. unilateral vestibular dysfunction
    1. nystagmus
    2. saccedes
29
Q

what do the VSR and VCR help with?

A

postural adjustments

30
Q

what structures are involved with the VSR?

A
  1. otoliths (utricle and saccule) project to LVN
  2. axons descend to antigravity muscles at all levels of the spinal cord
31
Q

what structures are involved with the VCR?

A
  1. MVN axons descend in MLF to upper cervical levels of spinal cord
    • these help dictate head position in response to head rotation
32
Q

how does the VSR work?

A

Head is tilted to one side

  1. Canals and otoliths are stimulated ipsilaterally (and inhibited contralateral)
  2. Increased input through the vestibular nerve to the vestibular nuclei ipsilaterally
  3. Impulses transmitted through the lateral & medial vestibulospinal tracts to the spinal cord

** result in increased lateral extension of trunk on side of head tilt, increased flexion contralaterally

33
Q

Damage to the VSR/VCR would result in what?

A

Postural instability, difficulty sensing falling/tipping

Truncal ataxia

34
Q

what is truncal ataxia?

A

incoordination, unstable trunk movement during movement

Neurophysiology (9 decks)

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