Cranial Nerve III, IV and VI
- 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.
Section:
Cranial Nerves III, IV and VI
Page 11 of 11
