title: 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.
authors.affiliation: Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia.
authors.forename: G M
authors.initials: GM
authors.lastname: Halmagyi
authors.forename: S T
authors.initials: ST
authors.lastname: Aw
authors.forename: I
authors.initials: I
authors.lastname: Dehaene
authors.forename: I S
authors.initials: IS
authors.lastname: Curthoys
authors.forename: M J
authors.initials: MJ
authors.lastname: Todd
mesh_terms: D000328:Adult; D001927:Brain Diseases / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D004027:Diencephalon / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality; D006257:Head; D006801:Humans; D008297:Male; D008636:Mesencephalon / Q000503:physiopathology*; D008875:Middle Aged; D009068:Movement; D009759:Nystagmus, Pathologic / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D011149:Pons / Q000503:physiopathology; D011187:Posture; D013681:Tegmentum Mesencephali / Q000503:physiopathology; D014102:Torsion Abnormality