Walsh & Hoyt: Abducens Nerve Pareses

When a unilateral or bilateral abducens nerve paresis occurs in the setting of an intracranial mass lesion, it usually represents a nonlocalizing sign of increased ICP. The abducens nerve has a long subarachnoid course during which it lies between the brain stem and the clivus. With increased ICP, one or both abducens nerves become compressed between the pons and the basilar artery or are stretched along the sharp edge of the petrous bone. In patients with increased ICP, the abducens paresis is rarely, if ever, complete and tends to resolve rapidly (within days to weeks) once ICP is lowered. There are so many cases of intracranial tumor associated with increased ICP and some weakness of one or both abducens nerves that such involvements as isolated occurrences are neither falsely localizing nor of topical diagnostic significance.