Head-shaking nystagmus

Head-shaking nystagmus. Head-Shaking Nystagmus (HSN) is a latent spontaneous vestibular nystagmus provoked by rapid passive head shaking around a vertical axis. HSN is not specific in distinguishing peripheral hypofunction from more central vestibular imbalances. This test is an excellent bedside test for detecting unilateral vestibular hypofunction but further rotatory and caloric testing will be necessary to clarify the patient’s condition.