Dissociated vertical nystagmus and internuclear ophthalmoplegia from a midbrain infarction
R. S. Marshall, R. L. Sacco, R. Kreuger, J. G. Odel and J. P. Mohr
Department of Neurology, Columbia-Presbyterian Medical Center, New York, NY 10032.
We describe a patient with a dissociated vertical nystagmus and an
internuclear ophthalmoplegia. The vertical nystagmus consisted of a left
downward nystagmus with a synchronous right intorting nystagmus when the
patient looked down and to the left. This rare type of nystagmus has been
described both in isolation and in association with an internuclear
ophthalmoplegia. Previous authors postulated a lesion in the midbrain in
the region of the medial longitudinal fasciculus. In our patient, a
discrete midbrain infarction was demonstrated on magnetic resonance imaging
in the hypothesized location, thus providing supportive anatomical evidence
for a vertical gaze coordination pathway in the region of the medial
longitudinal fasciculus.
