Correct! This is seesaw nystagmus, a disconjugate pendular oscillation in the torsional plane; one eye rises and intorts, the other eye falls and extorts. Seesaw nystagmus arises from a disturbance in the diencephalic and rostral midbrain gaze generators. It is often detected in early childhood. Common causes are sellar tumors such as craniopharyngiomas

, pituitary adenomas, and other masses. Seesaw nystagmus may also be a congenital finding without apparent structural alterations in the brain.

Chiari malformation is not the right answer; it causes downbeat nystagmus. Multiple sclerosis does cause a pendular nystagmus, but not usually with this seesaw pattern. Superior oblique myokymia causes a nonrhythmic monocular torsional movement, very unlike what you saw here.

This patient is reporting that viewed objects appear to oscillate (“oscillopsia”), a sensation that occurs when the amplitude of the pendular oscillation is high. Superior oblique myokymia generates a momentary illusion of visual blur or diplopia and a sensation that the affected eye is twitching.

There is no effective medical treatment for seesaw nystagmus.