Is benign paroxysmal positional vertigo underdiagnosed in hospitalised patients?

OBJECTIVES To investigate the proportion of sufferers of benign paroxysmal positional vertigo among hospitalised patients in Hong Kong who complained of dizziness, and to determine the predictive values and likelihood ratios of classical presenting symptoms. DESIGN Cross-sectional study. SETTING Convalescence/rehabilitation hospital, Hong Kong. PATIENTS A cohort of 88 newly admitted patients, who complained of dizziness or complained of having had dizziness in the 2 weeks prior to admission from September 2005 to February 2006. MAIN OUTCOME MEASURES Presence of the pathognomonic nystagmus of benign paroxysmal positional vertigo. RESULTS Five patients had benign paroxysmal positional vertigo, all with the posterior type. The frequency of its occurrence among patients complaining of dizziness was 6% (95% confidence interval, 1-11%), which was more than double the figure of 3% in our local convalescence/rehabilitation hospitals, though this difference was not statistically significant. Regarding the five identified patients, in two it involved the left ear, in two others the right ear, and in one it was bilateral. All four classical presenting symptoms had low positive predictive values, high negative predictive values, and small likelihood ratios. CONCLUSION Benign paroxysmal positional vertigo in the setting of a convalescence/rehabilitation hospital in Hong Kong seems to be underdiagnosed. Small and insignificant likelihood ratios for the classical presenting symptoms preclude their use in making the diagnosis. However, absence of these symptoms in a clinical setting of low occurrence rate can be regarded as against the diagnosis.