Material and Methods
Patients were included prospectively and consecutively in the study. The study was conducted in the Otorhinolaryngology and Audiology Clinic of the tertiary university hospital between October 2017 and September 2018. Demographic characteristics of the patients and pathological SCC detected by examination and diagnostic maneuver for BPPV patients were recorded. VOR gain was calculated in all patients and all six SCCs. Two sub-study groups were formed according to age (<50 or >50). The study was prepared with the reporting guideline of the STROBE checklist.
Inclusion: Only patients with complaints of acute onset vertigo (<5 days) were included in the study. The diagnosis of BPPV was made by examination, clinical history, clinical head impulse test (cHIT), and Dix Hallpike maneuver for vertical SCCs and examination, clinical history, clinical head impulse test (cHIT), and roll test for the lateral SCC. Vestibular Neuritis was diagnosed by medical history, physical examination, and caloric tests. The final diagnosis in VN patients was made by caloric test (irrigation of each ear with water at a temperature of 30 and 44 °C) A 20% difference calculated by Jongkees formula between the ears was accepted a pathological response. Meniere’s disease (MD) diagnosis was made in accordance with the diagnostic criteria of AAO-HNS Committee on Hearing and Equilibrium Meniere’s Disease [8].
Exclusion: The patients with immunocompromised conditions, autoimmune system diseases, malignancy, history of ear surgery, history of migraine, and history of antivertigo drugs in the last two weeks excluded from the study. Patients who did not receive the three diagnoses included in this study during or after the study protocol and the findings of these patients were not included in the final analysis.
vHIT protocol : Initially, the physiological lower limit of VOR gain was determined in 20 healthy participants and recorded by the instrument (Fig. 1) . The accepted lower value of VOR gain determined as 0.9 for the lateral SCCs and 0.7 for vertical SCCs. vHIT protocol of Micromedical Technologies Company’s VisualEyes™ Four-Canal-Videonystagmography (VNG) instrument was used for the test. This test consists of 3 parts. The first part is Lateral (Left Lateral: LL - Right Lateral: RL) test which is used for examination of lateral SCCs (LSCC). The second and third parts are RALP (Right Anterior : RA - Left Posterior: LP) and LARP (Left Anterior: LA - Right Posterior: RP) tests which are used for examination of vertical canals. During the test, fast pushing force is applied to patient’s head with approximately 20°-30° angle by audiologist/physician according to SCCs canal axis. Patients were asked to unloose her/his head, not to contract trapezius muscle and not to turn her/his eyes away from the point adjusted on the wall in 1.5-meter-distance from the patient. For each canal, at least 10-15 head push movements were applied. Lateral, RALP, LARP parameters of all patients were evaluated and VOR gains for six SCCs were determined separately. As a result of VHIT implemented on 20 normal patients, standard VOR values were priorly recorded by the instrument. Normal standard lower value of VOR was accepted as 0.92 for lateral canal and 0.74 for vertical canals. Based on these values VOR gain values of patients were examined.
Statistical Analysis: Data for the study were deposited with an electronic file. The findings analyzed by the SPSS 22.0 (SPSS Inc., Armonk, NY) software system. The normality assumption was measured by the Kolmogorov Smirnov test. Categorical variables were compared with the chi-square test, and scale variables were compared with the Kruskal-Wallis test. Sensitivity and specificity were calculated for all and each SCCs causing BPPV. Results with a significance coefficient of p>0.05 will be considered statistically significant.
Ethics Committee Approval: Verbal and written consent was obtained after all participants were informed. All procedures performed in studies involving human participants were following the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.