Sign Up for a Free Account
  • Updated 07.03.2023
  • Released 01.12.2000
  • Expires For CME 07.03.2026

Third nerve palsy



Adults with a vasculopathic profile and isolated third nerve palsies usually have reversible ischemic damage to the extra-axial portion of the nerve, a condition that resolves spontaneously within three months. However, patients at any age may rarely harbor life-threatening intradural cerebral aneurysms and other serious conditions. Because ischemic and nonischemic causes cannot be confidently distinguished by clinical criteria, all patients with isolated third nerve palsies should undergo prompt neuroimaging aimed at identifying a responsible aneurysm, regardless of whether the pupil is spared or involved. Except in children, pregnant women, and young adults, CT and CTA are preferred over MRI and MRA because of accessibility and conspicuity of blood vessels. If the reviewing radiologist is expert at excluding aneurysm and the imaging is of adequate quality, noninvasive imaging should detect cerebral aneurysms that cause third nerve palsies. If the imaging review is negative for aneurysm, further work-up can be deferred in adults with a vasculopathic profile to allow for spontaneous recovery of a presumed ischemic lesion within three months. In children, young adults, older adults without a vasculopathic profile, and adults with a vasculopathic profile whose palsy has worsened or not fully recovered within three months, further evaluation is indicated. Patients with nonisolated third nerve palsies may have intracranial inflammations or cancer; they should undergo MRI. If imaging is negative, further investigation, including lumbar puncture, should be undertaken.

Key points

• Third nerve palsy produces some combination of ipsilateral ptosis, mydriasis, and ophthalmoplegia.

• For purposes of evaluation, third nerve palsies should be divided into those that are not accompanied by other pertinent neurologic or systemic manifestations (“isolated palsies”) and those are accompanied by other pertinent manifestations (“nonisolated palsies”).

• Isolated third nerve palsies in patients with arteriosclerotic risk factors are usually caused by ischemia of the extra-axial portion of the nerve, but because clinical features do not allow exclusion of aneurysm, adults should undergo prompt imaging by CT and CTA and children and pregnant women by MRI and MRA.

• Aneurysmal clipping appears to lead to complete recovery from the palsy in 50% or more of patients, whereas coiling leads to complete recovery in about 33%, but the approach to the aneurysm must be based on what is safest and most effective in dealing with the aneurysm.

• Nonisolated acquired third nerve palsies may be caused by neoplasms, brainstem infarctions, inflammations, and extradural (cavernous sinus) aneurysms, but not by life-threatening intradural aneurysms; patients should undergo neuroimaging and other evaluations directed to the topographically localizing signs and symptoms.

• Acute third nerve palsies in patients over 55 years of age with headache, scalp tenderness, or jaw claudication may rarely be caused by giant cell arteritis, so evaluation must be directed at that condition.

• Diplopia may be alleviated by occlusion of the nonfixating eye by means of a patch, spectacle occluder, or opaque contact lens.

• Eye muscle surgery can be successful in restoring single binocular vision in some patients with intractable diplopia.

Historical note and terminology

The terms “third nerve palsy” and “oculomotor nerve palsy” are interchangeable.

This is an article preview.
Start a Free Account
to access the full version.

  • Nearly 3,000 illustrations, including video clips of neurologic disorders.

  • Every article is reviewed by our esteemed Editorial Board for accuracy and currency.

  • Full spectrum of neurology in 1,200 comprehensive articles.

  • Listen to MedLink on the go with Audio versions of each article.

Questions or Comment?

MedLink®, LLC

3525 Del Mar Heights Rd, Ste 304
San Diego, CA 92130-2122

Toll Free (U.S. + Canada): 800-452-2400

US Number: +1-619-640-4660



ISSN: 2831-9125