Evaluation of the Relationship between Video Head Impulse Test Findings and Vestibular Nerve Anatomical Measurements in Patients with Benign Paroxysmal Positional Vertigo

Objective: This study aimed to evaluate the relationship between video head impulse test results and vestibular nerve changes in patients with benign paroxysmal positional vertigo (BPPV).Material and Methods: Thirty-four patients (6 males, 28 females; age range 18-65) presenting with vertigo were included. All patients underwent contrast-enhanced magnetic resonance imaging to exclude cerebellopontine angle tumours. MRI measurements of the cerebellopontine angle, internal acoustic canal, vestibular nerve long and short axes, and cross-sectional area were performed. All participants underwent vHIT testing, and the results were compared between the affected and unaffected sides.Measurements were obtained in the axial plane aligned with the internal acoustic canal and performed by experienced radiologists.These findings were interpreted as reduced VOR gain rather than true semicircular canal hypofunction.Results: Ten patients had lateral semicircular canal involvement. Reduced VOR gain was observed in the affected canals. Twelve patients had anterior semicircular canal involvement, and 12 had posterior canal involvement. The vestibulo-ocular reflex (VOR) gains on the affected sides were lower compared to the unaffected sides (0.54-0.78 for affected canals and 0.84-0.98 for unaffected canals). However, there were no statistically significant differences in MRI measurements of the long axis of the vestibular nerve, short axis, or cross-sectional area between the affected and unaffected sides (p-values 0.836, 0.626, and 0.521, respectively).Conclusions: vHIT proved to be an effective and reliable method for detecting the affected semicircular canal in BPPV. Despite changes in VOR gains, there were no significant differences in the MRI measurements of the vestibular nerve between the affected and unaffected sides.