INTERNUCLEARING ophthalmoplegia, sometimes called the syndrome of the medial longitudinal fasciculus, is an abnormality of oculomotor function manifested by paresis of adduction on attempted horizontal gaze and associated with nystagmus of the abducting eye. Adduction on convergence may be preserved. This syndrome is of considerable value in anatomic and etiologic diagnosis and is attributed to a lesion of the medial longitudinal fasciculus between the brain stem center for horizontal conjugate gaze and the nuclear complex of nerve III.
Internuclear ophthalmoplegia may be unilateral or bilateral. The bilateral form is the more common and usually is due to multiple sclerosis. It also has been observed with inflammatory disease, vascular disease, and tumors. Unilateral internuclear ophthalmoplegia is uncommon and usually is due to an infarct of the brain stem tegmentum.
Although this abnormality has been attributed to a lesion of the medial longitudinal fasciculus, few cases of either the unilateral or
HARRINGTON RB, HOLLENHORST RW, SAYRE GP. Unilateral Internuclear OphthalmoplegiaReport of a Case Including Pathology. Arch Neurol. 1966;15(1):29–34. doi:10.1001/archneur.1966.00470130033003
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