Change in head posture and character of nystagmus in a patient with neurological upbeat nystagmus.

Purpose: To report a case of a patient with chin-up head posture and presumed congenital toxoplasmosis chorioretinal scars, who had a change in the character of the nystagmus and therefore the head posture following treatment for a neurological upbeat nystagmus.

Case report: A 5 month old female presented with a chin up head posture and upbeat nystagmus. Magnetic resonance imaging of the brain revealed an arachnoid cyst in the area of the pineal gland. Nine months after cyst-peritoneal shunt surgery, the upbeat nystagmus was dampened but change in character to a rotary nystagmus worse on the left gaze. The patient had assumed a left face turn, shifting the null point from the vertical to the horizontal plane. The left face turn was successfully corrected at age eight years with a Kestenbaum procedure.

Conclusion: This case emphasizes the possibility of having two distinct types of nystagmus associated with two etiologies. In this case, an acquired upbeat nystagmus secondary to an arachnoid cyst, and a congenital left rotary nystagmus from the chorioretinal scars. Furthermore, there can be a change in head position and character of nystagmus after treating the cause of the central motility disorder, thereby affecting the choice and timing of surgical intervention to correct the head positioning.