Two children with periodic alternating gaze deviation, presenting at birth in 1 patient and at 2 months in the other, are reported from the New England Medical Center, Tufts University, Boston, MA. The eyes conjugately drifted from one side to the other. With the head stabilized, a regular nystagmus of low frequency and large amplitude was seen when the patient attempted to direct the eyes away from the gaze bias. Compensatory head turning was noted in both patients. MRI showed multiple congenital abnormalities of the posterior cranial fossa. In 1 patient a left renal aplasia and a right supra-adrenal neuroblastoma were diagnosed by ultrasonography and by resection at 4 weeks of age. 
COMMENT. The periodic alternating gaze phenomenon is rare and points to cerebellar disease, with malformation of the inferior cerebellar vermis as the specific underlying lesion. The association with neuroblastoma in 1 patient is a coincidence since symptoms of opsoclonus were not described.