Central Vestibular Instability Nystagmus (Periodic Alternating Nystagmus)
Central vestibular instability nystagmus (periodic alternating nystagmus) is an unusual form of jerk nystagmus that can be congenital (as a form of CMN) or acquired (especially with Arnold-Chiari malformation). The nystagmus periodically changes direction owing to a shifting null point (Video 13-2). The cycle begins with a typical jerk nystagmus, which slowly damps; this leads to a 10- to 20-second period of no nystagmus, followed by jerk nystagmus in the opposite direction. The cycle repeats every few minutes. Some children adopt an alternating head turn to take advantage of the changing null point.
Central vestibular instability nystagmus (periodic alternating nystagmus).
Table 13-2 Ocular Conditions Associated With Congenital Sensory Nystagmus
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.