title: See-saw nystagmus due to unilateral mesodiencephalic lesion.
abstract: See-saw nystagmus is a unique torsional-vertical eye movement disorder with a characteristic appearance. It is a pendular nystagmus with two distinct components: a conjugate torsional component and a disjunctive vertical component. In those cases of see-saw nystagmus in which a focal lesion has been identified, the lesion is usually a bilateral, symmetric lesion located at the mesodiencephalic junction. We report an unusual case of see-saw nystagmus which was due to a strictly unilateral mesodiencephalic lesion. Furthermore, the see-saw nystagmus had, in this case, a jerk wave-form rather than the usual pendular wave-form, with the torsional component of the jerk see-saw nystagmus beating toward the side of the lesion. These observations have an impact upon the localizing and lateralizing significance of torsional nystagmus in general and of see-saw nystagmus in particular.
authors.affiliation: Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia.
authors.forename: G M
authors.initials: GM
authors.lastname: Halmagyi
authors.forename: W F
authors.initials: WF
authors.lastname: Hoyt
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D004027:Diencephalon; D005133:Eye Movements; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D009759:Nystagmus, Pathologic / Q000209:etiology*; D013786:Thalamic Diseases / Q000150:complications* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed