Isolated abducens nerve palsy: MR imaging findings.

The abducens nerve, the sixth cranial nerve, innervates the lateral rectus muscle of the eye and is responsible for lateral horizontal ocular movement. A wide variety of abnormalities, both primary to the nerve itself and secondarily involving the nerve, can paralyze the abducens nerve. MR imaging offers the best opportunity to detect the underlying abnormality causing abducens nerve palsy. In this pictorial essay, we illustrate the MR imaging features of numerous conditions that cause isolated abducens nerve palsy.