Vertical gaze paralysis and intermittent unresponsiveness in a patient with a thalamomesencephalic stroke.

A patient with paralysis of upward gaze and downward gaze, absent oculocephalic reflexes, and absent vertical saccades also demonstrated intermittent stupor over the first 9 days of presentation. Magnetic resonance imaging (MRI) demonstrated an infarct in the tegmentum of the mesencephalon including the right red nucleus and the periaqueductal area, superior to the oculomotor nucleus, and contiguous through the left thalamus. The infarct included the area around the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), as well as the midbrain reticular formation. Mechanisms are proposed for the unusual concurrent sign of intermittent unresponsiveness in this case.