Cranial nerves – visual disorders

Cranial nerves – visual disorders

1. Intro

   • Pupillary reflex abnormalities
     • Greater anisochoria in bright light
       • Parasympathetic deficit
         • Insufficient constriction
     • Greater anisochoria in dim light
       • Sympathetic deficit
         • Impairment of dilation
   • Visual abnormalities
     • Abnormalities of the pupillary reflex
     • Optic pathway lesions
     • Disorders of eye movement
   • Fundus oculi examination
   • Retina
     • Nasal
     • Temporal

2. Optic pathway lesions

   • Pre-chiasmal lesions
     • both visual field defects AND abnormalities of the pupillary reflexes
     • Central scotoma
   • Chiasmatic lesions
     • Bitemporal heteronomous hemianopia
     • Contralateral temporal hemianopia + ipsilateral central scotoma
       • When lesion is before decussation
   • Post-chiasmal lesions
     • No abnormalities to pupillary reflexes
     • 2 main defects
       • Homonimous lateral hemianopia
       • Altitudinal hemianopia

3. Optic nerve diseases

   • Optic neuritis (optic neuropathy)
     • Infectious disorders
     • Retrobulbar neuritis
     • Demyelinating optic neuritis
       • MS most common cause
     • can also be associated with neuromyelitis optica (Devic’s disease)
   • Papilledema

4. Disorders of eye movement

   • STRABISMUS (heterotropia)
   • Oculomotor (III) nerve palsy
     • Diplopia
     • If lesion is complete
       • Ptosis
       • Fixed dilated pupil
       • Eye deviated “downward and outward”
       • Elevation, depression and adduction are impaired
   • Trochlear (IV) nerve palsy
     • Vertical diplopia
     • Elevation of the affected eye and head tilt away from the side of the lesion
   • Abducens (VI) nerve palsy
     • horizontal diplopia
     • Eye abduction is impaired
   • ACUTE BILATERAL OPHTHALMOPLEGIA
     • Causes
       • Brainstem
       • Nerves
       • Cavernous sinus
       • Neuromuscolar junction
   • CONJUGATE GAZE PALSY
     • Causes are damage to
       • Voluntary system
       • Vestibulo-ocular reflex and neck proprioceptive afferents
       • Automatic
     • Pathologies are called horizontal oculomotor syndromes
       • Internuclear ophthalmoplegia
         • lesion of the MLF between nuclei VI and III
       • Horizontal gaze palsy
         • Damage to the VI nucleus
       • "One-and-a-half" syndrome
         • lesion of PPRF or nucleus VI and the MLF on the same side