Central Positional Nystagmus
In primary position, no nystagmus. When the patient is lying on the right side, a downbeating nystagmus develops after a certain latency. When the patient is lying on the left side (25 seconds), a more prominent downwardly-beating nystagmus is induced. In the headhanging position, also a downwardly-beating nystagmus can be seen (1 minute). All in all, in three different positions, a similar nystagmus can be induced. This is typical and the most relevant clinical sign of a central positioning or positional nystagmus. 1 minute 20 seconds: repetitive positioning maneuvers induce the same intensity of nystagmus, which can also be transient. 1 minute 40 seconds: lying on the right side.