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Cranial Nerve III, IV and VI
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Oculomotor, Trochlear, and Abducens Nerves Clinical Notes and Interpretation
  • Pupilary abnormalities result from CN II or CN III lesions.
  • With sympathetic chain lesions (Horner's Syndrome), affected pupils are smaller but still reactive.
  • Jerky nystagmus indicates a CNS lesion.
  • Vertical nystagmus indicates a brainstem lesion.
  • Nystagmus can also indicate a peripheral vestibular lesion.
  • Pendular nystagmus suggests a congenital disorder.
  • Dysfunction of the III, IV, or VI cranial nerves will produce diplopia with the head held in neutral, which can be further differentiated as described below:
    • CN III - Ptosis, inferior-lateral displacement of ipsilateral eye, and history of migraines.
    • CN IV - Diplopia worsens on downward gaze and improves when the head is tilted to the contralateral side.
    • CN VI - Medial deviation of ipsilateral eye and diplopia; improves when contralateral eye is abducted.
  • Patients may present with a cervical deviation to correct diplopia; this cervical deviation may be mistaken for a torticollis deformity.
  • Diplopia, except in rare instances (dislocated lens, retinal detachment), should disappear when one eye is covered.
  • With non-organic total blindness, the patient will likely demonstrate eye movements that will follow a moving object.


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Section: Cranial Nerves III, IV and VI
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Page 11 of 15
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