Abstract: Objective To observe and summarize the clinical characteristics of posterior semicircular canal benign paroxysmal positional vertigo(PSC-BPPV)at the time of acute onset, and to provide the clinical evidences for earlier diagnosis. Methods The clinical manifestations at the time of acute onset of 115 cases of patients with PSC-BPPV diagnosed were collected retrospectively. The gender, distributions of age, character of dizziness, state of patients at the time of acute onset, relationships between vertigo attack and head movement, nystagmus, associated symptoms, and auxiliary examination were analyzed. Results The clincal characteristics of PSC-BPPV at the time of acute onset were summarized as follow:(1) incidence among female patients was more higher than that of male patients; (2) participants aged over 50 years-old were more vulnerable to be affected;(3) acute vertigo occurred mainly at time of getting up, lying down, turning over or moving head actively or passively to a certain position, especially getting up in the morning; (4) the onset of severe vertigo was associated with nausea and vomitting; (5) part of patients presented characteric rotatory nystagmus of PSC-BPPV at the time of initial routine physical examination; (6) without symptoms and signs of cochlear and nervous system; (7) without related positive findings by cranial imaging(CT or MRI). Conclusion The diagnosis of PSC-BPPV should be considered if patients presented vertigo attack suddenly but without symptoms and signs of coclear and nervous system and related positive findings by cranial imagings. It is helpful to earlier confirming of the diagnosis by performing Dix-Hallpike manuvre.

Key words: Benign paroxysmal positional vertigo, Clinical characteristics, Emergency, Acute stage, Posterior semicircular canal