Isolated unilateral post-traumatic internuclear ophthalmoplegia.

A patient developed an isolated unilateral internuclear ophthalmoplegia (INO) after head trauma. An uncommon complication of closed head trauma, INO usually occurs bilaterally and is often associated with other neurologic deficits. The mechanism may be shear injury caused by angular acceleration leading to downward displacement of the posterior brainstem downward, stretching of the nerve fibers of the medial longitudinal fasciculus, or compression and tearing of its arterial supply.