Magnetic resonance imaging correlates of internuclear ophthalmoplegia.

Internuclear ophthalmoplegia (INO) is a gaze disorder characteristic of lesions involving the medial longitudinal fasciculus (MLF). Two patients aged 62 and 74 years presented with acute neurologic deficits characteristic of INO. Computed axial tomography (CT) did not detect abnormalities in the region of the MLF. Magnetic resonance imaging (MRI) however, demonstrated brainstem hypersignals with long T2 characteristics in the region of the MLF which correlated with the clinical symptoms. These cases illustrate the value of the MRI in evaluation of patients with INO and suggest that MRI is superior to CT in evaluating gaze disorders attributable to brain dysfunction.