Reduction in posterior semicircular canal gain by age in video head impulse testing. Observational study

and objectives: In-depth assessment of the vestibulo-ocular reflex with the new video systems available provides information on various previously-unidentified characteristics in patients with peripheral vestibular disorder. The aim of this work is to quantify how often pathological gain (uni- or bilateral) in the posterior semicircular canal (PSC) gain appears in video head-impulse testing (vHIT) with preservation of the gain in the rest of the semicircular canals, and to analyse the relation of this frequency with patient age and/or diagnosis.

This was a prospective observational study on adults referred to our unit between June 2012 and February 2014. Age, sex, pathological antecedents, prior history of vestibular pathology, diagnosis and time of evolution of the clinical picture and its characteristics were recorded. Each patient underwent a complete otoneurological examination, including vHIT (Otometrics®). Depending on suspected diagnosis, patients also received cervical vestibular evoked myogenic potential (VEMP) testing, tonal audiometry and speech test, as well as assessment by Neurology and/or nuclear magnetic resonance or computed axial tomography scan imaging study.

In all, 363 patients were assessed; 57 (16%) patients (33 males and 24 females; mean age, 57 ± 15 years) showed pathological PSC gains, 46 (81%) unilateral and 11 (19%) bilateral. Ménière's Disease was the most frequent diagnosis, followed by benign paroxysmal positional vertigo (27%). Patients with unilateral involvement were younger than those with bilateral (55 vs. 68 years; p=0.03). In the patients with bilateral involvement, PSC gain and age were related (-0.7; 0.04) and the gain value was symmetrical in both ears (0.7; p=0.05). The gain in the anterior and horizontal canals tended to decrease with age, but without statistical significance in our sample.

Of the patients referred for an otoneurological consultation, 16% showed pathological PSC gain (unilateral in 81% and bilateral in 19% of the cases). This gain involvement was attributable to age when the gain was bilateral and symmetrical.