Jerk-waveform see-saw nystagmus due to unilateral meso-diencephalic lesion

Abstract

See-saw nystagmus is an uncommon but highly characteristic eye movement disorder comprising intorsion and elevation of one eye, with synchronous extorsion and depression of the other. It generally has a pendular waveform and is due to a midline, extrinsic, suprasellar mass lesion compressing or invading the brainstem bilaterally at the meso-diencephalic junction. This report deals with the clinical and MRI findings in three patients (and binocular three-dimensional quantitative oculographic findings in one patient) with a jerk waveform see-saw nystagmus due in each case to a unilateral meso-diencephalic lesion. In each patient the torsional component of the nystagmus fast phases rotated the upper poles of the eyes toward the side of the lesion. Jerk see-saw nystagmus can be clinically indistinguishable from pendular see-saw nystagmus and from the torsional-vertical nystagmus which occurs with medullary lesions. We propose that jerk see-saw nystagmus is due to unilateral inactivation of the torsional eye-velocity integrator, thought to be in the interstitial nucleus of Cajal, with sparing of the torsional fast-phase generator, thought to be in the adjacent rostral interstitial nucleus of the medial longitudinal fasciculus.

Paroxysmal ocular tilt reactions after mesodiencephalic lesions: Report of two cases and review of the literature

“…INC is a neural integrator for vertical and torsional eye movements and inactivation of INC causes ipsiversive torsional nystagmus, gaze-holding deficit for vertical and torsional saccades (GEN), and limited vertical saccades without slowing [1,5]. INC lesions also produce jerky seesaw nystagmus [13]. In contrast, excitation of INC or riMLF would cause tonic ocular torsion in the same direction, i.e.…”

Eye movement deficits after unilateral mesencephalic lesions

“…Otherwise, the subjects have to perform head movements in the roll plane to elicit torsional saccades. The ipsilesional torsional saccades in a patient with a unilateral mesencephalic lesion can be slower than normal 12,13 or even absent. 8,10 Slow ipsilesional torsional saccades can occur independently of the presence of torsional nystagmus, which may beat contralesionally 8,10 or ipsilesionally.…”

“…8,10 Slow ipsilesional torsional saccades can occur independently of the presence of torsional nystagmus, which may beat contralesionally 8,10 or ipsilesionally. 12 Torsional saccade velocities to the contralesional side are normal 13 or slightly reduced, 10 or have not been determined. 8,12 up-and down-saccades Unilateral mesencephalic lesions can lead to a marked slowing of up-and down-saccades or to an upward 16 or up-and downward gaze paralysis.…”

“…12 Torsional saccade velocities to the contralesional side are normal 13 or slightly reduced, 10 or have not been determined. 8,12 up-and down-saccades Unilateral mesencephalic lesions can lead to a marked slowing of up-and down-saccades or to an upward 16 or up-and downward gaze paralysis. [16][17][18] Often, the velocities for upand down-saccades are equally affected, 12,13,19 but down-saccades can also be slower than up-saccades.…”

“…10,[12][13][14][15] These measurements can then be related to lesions identified by highresolution MRI, which also allows identification of small lesions from which patients generally recover. In contrast, earlier studies on localization depended mainly on the findings of autopsies of patients with large lesions.…”