INTRODUCTION
Vestibular schwannomas (VS) make up approximately 8% of brain tumours and are found in about 1 in 100,000 persons annually11Hojjat H., Svider P., Davoodian P., Hong R., Folbe A., Eloy J.A., et al: To image or not to image? A cost-effectiveness analysis of MRI for patients with asymmetric sensorineural hearing loss. Laryngoscope 2017; 127: pp. 939-944.
Asymmetric sensorineural hearing loss (ASNHL) and tinnitus are the major presenting symptoms in these patients. There is currently insufficient evidence to recommend a strategy that relies entirely on asymmetry at any single auditory pure-tone threshold.
Despite its vestibular nerve origins, the role of vestibular function testing in VS is poorly defined. Analysis of vestibular functioning with caloric testing or Vestibular Evoked Myogenic Potentials (VEMPs) to diagnose VS has yielded high sensitivity and low specificity results22Chiarovano E, Darlington C, Vidal PP, Lamas G, de Waele C. The role of cervical and ocular vestibular evoked myogenic potentials in the assessment of patients with vestibular schwannomas. PLoS One. 2014 Aug 19;9(8):e105026.. Semicircular canal function analysis, using video head-impulse testing (vHIT), have demonstrated a reduced Vestibulo-Ocular Reflex (VOR) gain in VS33Taylor RL, Kong J, Flanagan S, Pogson J, Croxson G, Pohl D, Welgampola MS. Prevalence of vestibular dysfunction in patients with vestibular schwannoma using video head-impulses and vestibular-evoked potentials. J Neurol. 2015 May;262(5):1228-37.. Nevertheless, the role of the vHIT as a clinical screening tool for VS remains undefined.
The Vibration-induced nystagmus (VIN) test is a simple and reliable method for detecting vestibular asymmetry44Park H, Lee Y, Park M, Kim JShin J. Test-retest reliability of vibration-induced nystagmus in peripheral dizzy patients.J Vestib Res. 2010;20(6):427-31.. In the present study, we investigated the role of vHIT and VIN in diagnosing VS in a population of patients with ASNHL.