Paralytic Strabismus: Third, Fourth, and Sixth Nerve Palsy

Eye movement abnormalities constitute an important clinical sign that can be a manifestation of dysfunction of cranial nerves III, IV, and VI (the 3 ocular motor nerves). Specific motility deficits often have highly localizing value within the neuroaxis, serving to refine a differential diagnosis and guide management. This article reviews the key anatomic concepts, clinical presentation, differential diagnosis, and management of ocular motor nerve palsies. Dysfunction of an ocular motor nerve must be distinguished from other causes of abnormal eye movements, such as myasthenia gravis or thyroid eye disease, which are outside the scope of this article.