Section 3: Flashcards

1
Q

can cranial nerve dysfunction cause monocular diplopia?

A

no

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2
Q

what are some differentials if the patient has monocular diplopia

A

uncorrected astigmatism, cornea, cataract, Srx

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3
Q

if patient has horizontal diplopia, what muscles do you think are affected?

A

lateral or medial rectus

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4
Q

if patient has vertical diplopia, what muscles do you think are affected?

A

SO, IO, SR, or IR

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5
Q

what muscles may be affected if the patient has horizontal diplopia worse at far

A

lateral rectus

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6
Q

what muscles may be affected if the patient has horizontal diplopia worse at near

A

medial rectus

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7
Q

what muscles may be affected if the patient has vertical diplopia worse at far

A

IR or SR

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8
Q

what muscles may be affected if the patient has vertical diplopia worse at near

A

IO or SO

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9
Q

if patient moves chin up or down, their problem is likely

A

vertical muscle problem

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10
Q

if patient has a head turn, their problem is likely

A

horizontal muscle problem

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11
Q

if patient has a head tilt, their problem is likely

A

torsional component

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12
Q

where else does fibers from CN III travel to

A

iris sphincter and levator

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13
Q

what innervates the Obicularis

A

CN VII

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14
Q

oculosympathetic innervation goes to:

A

Mueller’s muscle/ Dilator

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15
Q

12 diagnostic tests you should run

A
  1. pinhole (if monocular diplopia)
  2. keratometry (if monocular diplopia)
  3. pupils
  4. cover test
  5. parks 3 step
  6. versions/ductions
  7. red lens/ maddox rod in 9 fields of gaze
  8. refraction
  9. phorometry
  10. saccades/OKN
  11. cranial nerve evaluation
  12. ocular health evaluation
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16
Q

most common ocular motor nerve palsies are

A
  • abducens, VI (44-57%)
  • trochlear, IV (21-28%)
  • oculomotor, III (15-17%)
  • multiple (5-13%)
17
Q

origin of oculomotor nerve

A

oculomotor nuclei and edinger westphal nuclei

only nucleus with sub nuclei

18
Q

superior branch of oculomotor nerve has the

A

SR, Levator

19
Q

inferior branch of the oculomotor nerve has the

A

IO, IR, MR

20
Q

what are the parasympathetic fibers of the oculomotor nerve

A

iris sphincter, ciliary muscle

21
Q

what are 4 signs of a complete CN III palsy

A
  1. ptosis
  2. mydriasis
  3. exotropia/ hypotropia
  4. pain (retro-orbital and peri-orbital)
22
Q

what are some differential diagnoses for 3rd nerve palsy

A
  • myasthenia gravis
  • thyroid eye disease
  • CPEO- chronic progressive external ophthalmoplegia
  • midbrain lesion
  • orbital fracture
  • Brown’s syndrome
23
Q

where are some proposed areas of injury for CN III palsies

A
  • exit from brainstem
  • herniation against tectorial region
  • superior orbital fissure
24
Q

what are some important aspects of congenital III nerve palsy

A
  • formed from absence or incomplete development of the III nerve nucleus or nerve
  • may have amblyopia
  • rare in comparison to acquired III nerve palsy
  • aberrant regeneration
25
Q

what do the rare central lesions in the nuclear (dorsal aspect of midbrain) present as?

A
  • bilateral ptosis and contralateral SR palsy
  • ipsilateral III palsy with limited SR action
  • can also have isolated muscle paresis
26
Q

what occurs with damage to edinger-westphal nucleus

A

pupils- 2 sides are fused so bilateral

27
Q

what occurs with damage to lateral subnuclei

A

ipsilateral IR, IO, MR

28
Q

what occurs with damage to medial subnuclei

A

contralateral SR

29
Q

what occurs with damage to central caudal sub nucleus

A

bilateral levators

30
Q

what are some causes of nuclear III palsy

A
  • infarction thrombosis or emboli (most common)
  • demyelination
  • tumor or neoplasm
  • thiamine deficiency (Wenicke’s)