Infection-Associated Ocular Cranial Nerve Palsies

Infections involve both afferent as well as efferent pathways of the visual system. It is important to understand the anatomical localization of the ocular cranial nerves because of the predilection of infectious agents toward specific regions. Isolated involvement of an individual ocular cranial nerve may occur anywhere along its course starting from the brainstem root exit to innervation-specific extraocular muscles in the orbit. It is intuitive that infections involving orbits, retro-orbital area, superior orbital fissure, cavernous sinus, subarachnoid space, and nerve root exit zones may cause, in isolation or combination, infranuclear ocular nerve palsies. Ophthalmoplegia can be caused either directly by the infectious agent or indirectly due to its complications. This chapter gives a holistic view of the ocular nerve palsies due to various infectious agents.