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B&B 2 (MM) > 3.12.14 Clinical Eye and Ear > Flashcards

3.12.14 Clinical Eye and Ear Flashcards

1
Q

Describe the effects of Parasympathetic ANS on the pupils

A

Constriction

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2
Q

Describe the effects of Sympathetic ANS on the pupils

A

Dilation

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3
Q

Describe the afferent limb of the Parasympathetic pupillary response.

A

Lens > retina > optic nerve > optic tract > PRETECTAL NUCLEUS (midbrain) > Edinger-Westphal nucleus

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4
Q

Describe the efferent limb of the Parasympathetic pupillary response.

A

Edinger-Westphal > CN3 > ciliary ganglion > SHORT ciliary nerves > constrictor muscles

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5
Q

Which important nucleus redirects afferent fibers to the Edinger-Westphal nucleus for the pupillary light reflex?

A

Pretectal nucleus

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6
Q

Which carries Parasympathetic fibers to the eyes: the long or short ciliary nerve?

A

Short ciliary nerve

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7
Q

Which carries Sympathetic fibers to the eyes: the long or short ciliary nerve?

A

Long ciliary nerve

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8
Q

What might cause dilated and unreactive pupils?

A

Damage to the efferent limb caused by:

  • Compression of CN3
  • Cavernous sinus fistula
  • Stroke in the midbrain (pretectal nucleus; Edinger-Westphal nucleus)
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9
Q

What is Marcus-Gunn? Symptoms?

What might cause it?

A

(Marcus-Gunn pupil) = afferent limb damage in Parasympathetic ANS control of pupil
Eye is less reactive to swinging light test; caused by:
- Stroke in optic nerve
- Unilateral cataract
- Optic neuritis

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10
Q

Describe the afferent limb of the Sympathetic pupillary response.

A

Cortex or posterior hypothalamus:

  • Emotional response
  • Pain sensation
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11
Q

Describe the efferent limb of the Sympathetic pupillary response.

A

Posterior hypothalmus > reticular formation (brainstem) > ciliospinal center (preganglionic sympathetic neurons of C8-T1) > T1/T2 nerves > across APEX OF THE LUNG > superior cervical ganglion > carotid sheath > cavernous sinus > long ciliary nerves and nasociliary nerves > radial dilator muscles

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12
Q

What is the name for a set of symptoms characterized by the loss of the efferent limb of sympathetic fibers that control the eye? Causes?

A

Horner’s syndrome; this also would include other sympathetic innervation of one side of the face:
Vasodilation, anhydrosis, miosis, ptosis
Caused by:
- Tumor in apex of the lung
- Surgery on carotid artery (fibers along the sheath)
- Brainstem stroke

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13
Q

What would cause ipsilateral blindness (entire field)?

A

Damage to the optic nerve

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14
Q

What sort of vision loss would accompany an optic tract lesion?

A

Contralateral homonymous heminaopsia (field opposite of the lesion)

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15
Q

What sort of vision loss would accompany an optic chiasm lesion?

A

Bitemporal hemianopsia (loss of lateral fields)

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16
Q

What sort of vision loss would accompany a lesion of Meyer’s loop (which lobe)?

A

(Temporal lobe)

Contralateral homonymous superior quadrantanopsia

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17
Q

What sort of vision loss would accompany a lesion of the parietal lobe?

A

Contralateral homonymous inferior quadrantanopsia

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18
Q

What sort of vision loss would accompany a lesion of the occipital lobe?

A

Contralateral homonymous hemianopsia

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19
Q

What sort of vision loss would accompany posterior cerebral artery occlusion?

A

Contralateral homonymous hemianopsia with macular sparing

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20
Q

What accounts for macular sparing in posterior cerebral artery occlusion?

A

A small branch of the middle cerebral artery (some people) to the tip of the occipital lobe

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21
Q

What is hippus?

A

Normal, rhythmic variation in pupil size

22
Q

What is physiologic anisocoria?

A

Normal difference in pupillary size (same person)

- Usually not more than one or two millimeters

23
Q

What is pharmacologic mydriasis

A

Dilation of the pupils pharmacologically

24
Q

What is Argyll-Robertson?

A

(Argyll-Robertson pupil)
aka “Prostitute’s pupil” - accomodates, but doesn’t react; neurosyphilis
Pupils will constrict when focusing on a close object; will not constrict in response to light

25
Q

Describe the path of CN3

A
  • Exits ventral midbrain
  • Courses near the posterior communicating artery beneath the cerebellar tentorium
  • Goes through cavernous sinus to the orbit
26
Q

Cavernous sinus lesions and transtentorial herniation are associated with dysfunction of…

A

Cranial nerve III (Oculomotor)

27
Q

If the patient is found leaning to one side, stating that this helps his vision, what might you expect?

A

Lesion of CN4, opposite to the side which he is leaning (compensates for loss of down and out movement)

28
Q

Which cranial nerve exits the brainstem dorsally (after crossing internally)

A

Cranial nerve IV (Trochlear)

29
Q

What motion of the eyes does the frontal lobe control (i.e. the right frontal lobe)

A

Directs eyes to move conjugately in the opposite direction (i.e. right frontal lobe controls looking to the left)
- Right frontal lobe cues the left lateral rectus (abducens); conjugate movement is coordinated by the medial longitudinal fasciculus (MLF)

30
Q

What is internuclear ophthalmoplegia? What location is affected? Describe the result of a unilateral lesion?

A
  • A deficit of conjugate movement of the eyes.
  • The medial longitudinal fasciculus (MLF) coordinates these movements.
  • Lesion to the MLF affects ipsilateral adduction (info from the contralateral abducens nucleus crosses over and ascends the MLF to the oculomotor nucleus)
31
Q

What structures may be affected in sensorineural hearing loss?

A

Cochlea (hair cells), cochlear nerve, cochlear nucleus, etc. (cochlear and retrocochlear)

32
Q

What structures may be affected in conductive hearing loss?

A

External auditory canal, tympanic membrane, ossicles (outer ear and middle ear)

33
Q

What is the Weber test? What results would you expect normally? Sensorineural hearing loss? Conductive?

A

Tuning fork to the vertex of the head. Sound lateralizes to (is louder in) one ear or the other

  • Normally: equilateral hearing/no lateralization
  • Sensorineural: Sound lateralizes to the unaffected ear
  • Conductive: Sound lateralizes to the affected ear (overcompensation of nerves)
34
Q

What is the Rinne test? What results would you expect normally? Sensorineural hearing loss? Conductive?

A

A test of bone versus air conduction of sound

  • Normally: Air > Bone (both ears)
  • Sensorineural: Air > Bone (both ears)
  • Conductive: Bone > Air (affected ear)
35
Q

What might you find by otoscopic examination?

A

Cerumen impactation
Otitis externa
Otitis media
Tympanic membrane perforations

36
Q

What can be diagnosed by audiometry?

A
  • Conductive vs. Sensorineural hearing loss
  • Frequencies sensed
  • Deficits (in decibels) of frequencies
37
Q

What is BAER’s? What does it test?

A

Brainstem Auditory Evoked Potentials

BAER’s helps in anatomical localization of lesions of the auditory nerve or brainstem

38
Q

What is electrocochleography (ECochG)?
Compound action potential (AP)?
Summating potential (SP)?
Interpretation of the ratio?

A

Measurement of the electrical activity within the cochlea after acoustic stimulation
AP = combined recording of numerous individual nerve action potentials
SP = potential arising from displacement of the basilar membrane
SP:AP is normally less than 0.5; increased pressure of the inner ear fluid will increase the ratio

39
Q

What six tests are commonly used to test cochlear nerve function/hearing?

A

Weber, Rinne, Otoscopic examination, Audiometry, BAER’s, Electrocochleography (ECochG)

40
Q

What are the three tests commonly used to test vestibular nerve function?

A

Rotational test, Caloric test, Electronystagmography (ENG)

41
Q

With respect to a rotational test spinning the pt to the right, what would you expect of the direction of:
Endolymph flow?
Slow phase nystagmus?
Fast phase nystagmus?

A

Endolymph: to the right (continuing the motion of the spin)
Slow: along with the endolymph
Fast: opposite of the endolymph (resetting vision)

42
Q

What is the mnemonic for normal caloric testing results?

A

COWS:
Cold = opposite (fast phase of nystagmus)
Warm = same (slow phase of nystagmus)

43
Q

What direction should the fast phase of nystagmus with peripheral lesion? Central lesion?

A

Peripheral: opposite of the lesion
Central: toward the lesion

44
Q

Vertigo is due to pathology of what structures?

A 
Labyrinths (peripheral)
Vestibular nerve (peripheral)
Vestibular nuclei (central)
45
Q

Sensation of impending faint (near syncope) is usually caused by…

A

Cardiovascular disorders

46
Q

Dysequilibrium is usually caused by…

A

Anxiety, multiple sensory deficits, or cerebellar dysfunction

47
Q

Ill-defined light-headedness is usually due to…

A

Hyperventilation or anxiety

48
Q

Peripheral conditions involving CN8 vestibular function include (6):

A 
Labyrinthitis
Meningitis
Trauma
Meniere's syndrome
Benign positional vertigo
Cerebellopontine Angle (CPA) tumors
49
Q

Meniere’s syndrome =

A

Idiopathic disorder

Paroxysmal attacks of hearing loss, vertigo, and tinnitus

50
Q

Cerebellopontine Angle tumors

A

usually acoustic Schwannomas
Vertigo, tinnitus, retrocochlear sensorineural hearing loss
Involvement of CN5 and CN7

51
Q

Central conditions involving CN8 vestibular function include (3):

A

Multiple sclerosis
Vascular (stroke)
Neoplasms

B&B 2 (MM) (22 decks)

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