Читать книгу Vestibular Disorders - Группа авторов - Страница 18

Head-shaking nystagmus is an additional method for demonstrating a left-right asymmetry in dynamic vestibular function. While wearing Frenzel glasses, the patient’s head is bent slightly forwards (30 degrees) to align the horizontal canals with earth horizontal. The head is shaken in the yaw plane at 2 deg/s, approximately 10–20 times. If there is a unilateral vestibular lesion, horizontal nystagmus with the fast phases beating to the intact ear (contraversive head-shaking nystagmus) is seen at the end of head shaking. Nystagmus may reverse thereafter. Normal subjects have no head-shaking nystagmus or only 1–2 beats. Vertical nystagmus observed after horizontal head shaking is a nonspecific sign, thought to imply central vestibulopathy. Ipsiversive head-shaking nystagmus (with the fast phase beating toward the lesioned ear) has been described in lateral medullary infarction [12].