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 December 10, 2018; expires December 10, 2021

This article includes discussion of third nerve palsy, isolated third nerve palsy, oculomotor nerve palsy, diplopia, ptosis, and mydriasis. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


The patient with third nerve palsy might harbor a life-threatening cerebral aneurysm or tumor. When third nerve palsy is accompanied by other pertinent abnormalities (“nonisolated third nerve palsy”), imaging should be directed at the expected location of the lesion, which is based on clinical features. When the third nerve palsy is the only pertinent abnormality (“isolated third nerve palsy”), imaging should be directed at identifying an aneurysm, regardless of whether the pupil is spared or involved. MRI and MRA are preferred in children; CT and CTA are preferred in adults, except in cases of aberrant regeneration of the third nerve, where MRI and MRA are preferred. If the reviewing radiologist is expert at excluding aneurysm, good quality noninvasive imaging will be sensitive enough to detect a cerebral aneurysm that causes a third nerve palsy. If imaging is negative in adults, the palsy is likely to have resulted from extraaxial nerve ischemia, and further investigation should be deferred to allow natural recovery of the palsy, which will occur within 3 months of onset. If recovery of the palsy does not occur within that period, brain imaging should be repeated. If imaging is negative in children, a postviral cause may be presumed, and lumbar puncture and other investigations should be deferred to allow recovery of the palsy, which is likely.

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 accompanied by other pertinent manifestations (“nonisolated palsies”) and those without other pertinent manifestations (“isolated palsies”).


• 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 evaluation based on the topographically localizing signs and symptoms.


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


• Acute third nerve palsy in patients over age 55 with headache or jaw claudication may 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.


• Aneurysmal clipping leads to complete recovery from the third nerve palsy in 50% or more of patients, whereas coiling leads to complete recovery in about 33%.


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

Historical note and terminology

In 1930, Collier reported a series of third nerve palsies in diabetes mellitus, pointing out that the palsy could be the first manifestation of diabetes, and that almost all the cases resolved spontaneously (Collier 1930). A review of 130 cases of third nerve palsy from Wills Eye Hospital in Philadelphia in 1964 revealed that about 20% were associated with diabetes mellitus (Green et al 1964).

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