Isolated Unilateral Adduction Paresis of the Right Eye Due to a Contusion in the Subnucleus of Oculomotor Nerve

In this report we present a 45 year old man with horizontal diplopia following minor head trauma. Neurological examination was normal except for unilateral adduction paresis of the right eye. Brain magnetic resonance imaging (MRI) revealed a contusion area 7 mm in diameter at the inferior-posterior portion of the mesencephalon. We thought that this contusion affected the sub-nucleus of oculomotor nerve and caused isolated adduction paresis of the right eye. This relatively rare entity is discussed in the light of the available literature.