Isolated fourth nerve palsy

Lulu LCD Bursztyn MD (Dr. Bursztyn of Western University has no relevant financial relationships to disclose.)
Jonathan D Trobe MD, editor. (Dr. Trobe of the University of Michigan has no relevant financial relationships to disclose.)
Originally released January 12, 2000; last updated April 26, 2017; expires April 26, 2020

This article includes discussion of isolated fourth nerve palsy, superior oblique palsy, Superior oblique paralysis, and trochlear nerve palsy. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Isolated fourth nerve palsy is usually benign. The most important etiologies for a fourth nerve palsy are decompensation of a congenital weakness, head or surgical trauma, extra-axial nerve ischemia, nerve inflammation, and local compression by tumor. Thyroid-related orbitopathy, skew deviation, myasthenia gravis and sagging eye syndrome can mimic fourth nerve palsy. Spectacle prisms and strabismus surgery can be effective treatments for most unresolved cases.

Key points

 

• Isolated fourth nerve palsy is usually benign and typically does not require an extensive evaluation.

 

• Non-isolated fourth nerve palsy should undergo imaging and evaluation directed to the topographically localizing symptoms and signs.

 

• The most important etiologies for a fourth nerve palsy are decompensation of a congenital weakness, head or surgical trauma, extra-axial nerve ischemia, nerve inflammation, and local compression by tumor.

 

• Thyroid-related orbitopathy, skew deviation, myasthenia gravis, and sagging eye syndrome can mimic fourth nerve palsy.

 

• Spectacle prisms and strabismus surgery can be effective treatments for most unresolved cases.

Historical note and terminology

The terms “superior oblique paralysis,” “trochlear nerve palsy,” and “fourth nerve palsy” are essentially interchangeable for the purposes of this review.

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