Active Head Auto-Rotations in Patients With Benign Paroxysmal Positional Vertigo

BACKGROUND: Utricular degeneration is the source of traveling otoconia inside the semicircular canals in patients with benign paroxysmal positional vertigo (BPPV). The underlying pathology is not clear. The aim of this study was to analyze vestibulo-ocular reflex (VOR) during sudden head accelerations in those patients since clinical reports designating an association of BPPV with inner ear problems are increasing. METHODS: VOR reaction to impulsive head rotations were tested in 34 patients with BPPV (13 lateral, 21 posterior canal BPPV) and 15 healthy subjects in a prospective controlled study. Main outcome measure was the gain (the ratio of head and eye velocity) of vertical and horizontal head auto-rotations to the pathologic and normal sides. RESULTS: All patients with BPPV and control subjects had normal gain (≥ 0.9) at 1 and 2 Hz but the gain decreased at higher frequencies. No statistically significant difference was found when comparing the gain between the horizontal head rotations toward the pathologic and those toward the normal side (P = 0.89, P = 0.90, P = 0.78, P = 0.20 and P = 0.16, at 1, 2, 3, 4 and 5 Hz, respectively) and between upward and downward vertical head rotations (P = 0.28, P = 0.53 and P = 0.15, at 1, 2 and 3 Hz, respectively) in patients with lateral and posterior canal BPPV. CONCLUSION: VOR gain was reduced in some patients. However, head auto-rotation test (HART) does not show any functional abnormality of VOR during head rotations toward the pathologic side. HART is not suitable as a screening test for BPPV.