Perverted Head Shaking Nystagmus in a Patient with Cerebellar Infarction

Perverted head shaking nystagmus (pHSN) refers to a phenomenon that the head shaking nystagmus occurs in a different plane than the vestibular stimulus. pHSN signifies central vestibular dysfunction. The authors describe a patient who showed an isolated downbeat head shaking nystagmus from a focal cerebellar infarction in the territory of the medial posterior inferior cerebellar artery. Head shaking maneuver should be applied to all patients with isolated vertigo from a presumed vascular origin.