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Introduction

Benign paroxysmal positional vertigo (BPPV) is the most common cause for peripheral vestibular vertigo. BPPV is characterized by short repeated episodes of mild to intense vertigo induced by special head position changes, and accompanied by imbalance and nausea . The currently accepted mechanism for the BPPV is that otoconia derived from the utricular macula moves to the semicircular canal. Otoconia is the small crystals of calcium carbonate. These particles make a change of the endolymph flow in the semicircular canal and induce the abnormal excitability of vestibular receptors. About 90% of BPPV patients are affected in posterior semicircular canal . Most of them often complain of loss of balance and unstable gait during and between the paroxysmal vertigo attacks. The diagnosis of BPPV is confirmed by patient history and provocation maneuvers, such as the Dix–Hallpike test or the supine head-turning test. The main treatment of BPPV is to remove the otoconias by liberating maneuvers or Brandt–Daroff exercises . Those are noninvasive procedures for clearing of otoconias out of the canal and driving them back into the place where they should belong. Although the repositioning maneuvers are usually very effective in improving the vertigo, some patients still complain residual dizziness .

Benzodiazepines and antihistamines which are directed to suppress the vertigo are commonly used for BPPV patients. Although vestibular suppressants and antiemetic drugs are useful for acute treatment of vertigo, they are not effective for BPPV . Betahistine dihydrochloride is effective in improving the recovery rate and life quality of BPPV patients . It is an affinity for histamine H ₁ and H ₃ receptors. In addition, betahistine dihydrochloride improves the microcirculation of the labyrinth, and relieves pressure from endolymphatic fluid . Danhong injection (DHI), a traditional Chinese medicine, can effectively dilate blood vessels and improve microcirculation. DHI has been proven to be effective in improving cervical vertigo and posterior circulation ischemic vertigo . The reason that betahistine dihydrochloride improves the quality of life (QOL) of patients with BPPV is partly by dilating the blood vessels and improving the microcirculation of the labyrinth. In this study, we aimed to evaluate the effects of DHI on residual dizziness after successful repositioning treatment in patients with BPPV.