Third nerve palsy

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Background

  • Third (oculomotor) nerve, innervates eyelid muscles and external ocular muscles (except lateral rectus and superior oblique) [1]
  • Nerve also carries parasympathetic fibers on external surface allowing for pupillary constriction
  • Palsy causes diplopia except in lateral gaze (lateral rectus innervated by CN VI)
  • Ptosis, headache

Causes


Clinical Features

  • Eye deviates laterally and down
  • Pupil exam:
    • If dilated/nonreactive likely secondary to space occupying lesion
    • If pupil is spared likely ischemic etiology
  • Loss of accommodation

Differential Diagnosis

Diagnosis

  • If complete CNIII involvement with ptosis, mydriasis, and ophtalmoplegia:
    • assume a compressive etiology from an intracraneal anurysm.
    • Proceed to a CTA brain
  • If complete oculomotor nerve palsy without pupil involvement then strongly favor an ischemic process
    • Consider a CTA brain
    • Coronal reconstruction on CT will allow visualization of orbits to rule out compressive process
  • If associated with other neurologic deficits:
    • CTA brain followed by MRI/MRA brain

Management

  • If ischemic cause
    • Medical management with most self resolving in 6-8 wks
    • Ophthalmology f/u
  • If aneurysm/mass
    • Neurosurgery consult
  • If diplopia
    • No driving or operating heavy machinery

See Also

References

  1. Capo, H., M.D., Warren, F., M.D., Kupersmith, M. , M.D. Evolution of Oculomotor Nerve Palsies. J Clin Neuroophthalmol. 1992 Mar;12(1):21-5. (12)1:21-25, 1992.
  2. Appenzeller S, Veilleux, M. Clarke, A. Lupus. Third cranial nerve palsy or pseudo 3rd nerve palsy of myasthenia gravis? A challenging diagnosis in systemic lupus erythematosus. 2009 Lupus. Aug;18(9):836-40.
  3. Chaudhary,N. et al Imaging of Intracranial Aneurysms Causing Isolated Third Nerve Palsy. J. Neuro-Ophthalmol 2009;29:238-244