Third nerve palsy

Jonathan D Trobe MD (Dr. Trobe of the University of Michigan has no relevant financial relationships to disclose.)
Originally released January 12, 2000; last updated June 8, 2020; expires June 8, 2023

This article includes discussion of isolated and nonisolated third nerve (oculomotor) palsies. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Adults with isolated third nerve palsies usually have reversible ischemic damage to the extra-axial portion of the nerve, a condition that resolves spontaneously within 3 months. However, patients at any age may rarely harbor life-threatening intradural cerebral aneurysms. 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. CT and CTA are preferred over MRI and MRA because of accessibility. 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. 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 considered.

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 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 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 third nerve palsies may be caused by neoplasms, brainstem infarctions, and inflammations, 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 averted 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 essentially interchangeable.

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