Cranial nerves – visual disorders

Intro
1. Pupillary reflex abnormalities
  1. Greater anisochoria in bright light
    1. Parasympathetic deficit
      1. Insufficient constriction
  2. Greater anisochoria in dim light
    1. Sympathetic deficit
      1. Impairment of dilation
2. Visual abnormalities
  1. Abnormalities of the pupillary reflex
  2. Optic pathway lesions
  3. Disorders of eye movement
3. Fundus oculi examination
4. Retina
  1. Nasal
  2. Temporal
Optic pathway lesions
1. Pre-chiasmal lesions
  1. both visual field defects AND abnormalities of the pupillary reflexes
  2. Central scotoma
2. Chiasmatic lesions
  1. Bitemporal heteronomous hemianopia
  2. Contralateral temporal hemianopia + ipsilateral central scotoma
    1. When lesion is before decussation
3. Post-chiasmal lesions
  1. No abnormalities to pupillary reflexes
  2. 2 main defects
    1. Homonimous lateral hemianopia
    2. Altitudinal hemianopia
Optic nerve diseases
1. Optic neuritis (optic neuropathy)
  1. Infectious disorders
  2. Retrobulbar neuritis
  3. Demyelinating optic neuritis
    1. MS most common cause
  4. can also be associated with neuromyelitis optica (Devic’s disease)
2. Papilledema
Disorders of eye movement
1. STRABISMUS (heterotropia)
2. Oculomotor (III) nerve palsy
  1. Diplopia
  2. If lesion is complete
    1. Ptosis
    2. Fixed dilated pupil
    3. Eye deviated “downward and outward”
    4. Elevation, depression and adduction are impaired
3. Trochlear (IV) nerve palsy
  1. Vertical diplopia
  2. Elevation of the affected eye and head tilt away from the side of the lesion
4. Abducens (VI) nerve palsy
  1. horizontal diplopia
  2. Eye abduction is impaired
5. ACUTE BILATERAL OPHTHALMOPLEGIA
  1. Causes
    1. Brainstem
    2. Nerves
    3. Cavernous sinus
    4. Neuromuscolar junction
6. CONJUGATE GAZE PALSY
  1. Causes are damage to
    1. Voluntary system
    2. Vestibulo-ocular reflex and neck proprioceptive afferents
    3. Automatic
  2. Pathologies are called horizontal oculomotor syndromes
    1. Internuclear ophthalmoplegia
      1. lesion of the MLF between nuclei VI and III
    2. Horizontal gaze palsy
      1. Damage to the VI nucleus
    3. "One-and-a-half" syndrome
      1. lesion of PPRF or nucleus VI and the MLF on the same side

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Cranial nerves – visual disorders

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	Created by LewisLewis almost 11 years ago