Abduction saccadic movement slowed to either side without any limitation in the end position occurred in a patient. This ocular motor abnormality constituted a mirror image of the well-known internuclear ophthalmoplegia of adduction, and therefore, the present case is an internuclear ophthalmoplegia of abduction.
Internuclear ophthalmoplegia of either type demonstrates that a lesion between the center for conjugate gaze and the ocular motor nuclei can impair phasic activity of the eye muscles without reducing their tonic function.
Kommerell G. Internuclear Ophthalmoplegia of AbductionIsolated Impairment of Phasic Ocular Motor Activity in Supranuclear Lesions. Arch Ophthalmol. 1975;93(7):531-534. doi:10.1001/archopht.1975.01010020547013