Analysis of semicircular canal function as evaluated by video Head Impulse Test in patients with vestibular schwannoma.

Objective: The aim of the present study was to investigate the factors influencing semicircular canal function as evaluated by video Head Impulse Test (vHIT) in patients with vestibular schwannoma.

Methods: Twenty-four patients with untreated vestibular schwannoma underwent vHIT examination. The correlations between semicircular canal function and factors including age, tumor size, disease duration and hearing loss were evaluated.

Results: The functions of all three semicircular canals on the affected side evaluated by vHIT were significantly lower than those on the unaffected side. Although there were no significant correlations between semicircular canal function and age, tumor size or disease duration, a negative significant correlation between vestibulo-ocular reflex (VOR) gain as evaluated by vHIT and hearing loss was observed.

Conclusions: From the results of the relationship between hearing loss and VOR gain, the damage to the audio and vestibular systems in patients with VS may be correlated. As it has been suggested that tumor size was not a significant factor in the VOR gain evaluated by vHIT, multifactorial causes rather than the simple compression of the vestibular nerves alone may be related to the dysfunction of the semicircular canals in patients with vestibular schwannoma.