Rapid fluctuations in dynamic semicircular canal function in early Ménière’s disease

Ménière’s disease (MD) is characterized by fluctuations in labyrinthine function which are well known and objectively established for the auditory symptoms [1, 2]. It is also well known that it is disorders of balance, rather than hearing, which are the major symptoms during the early stages of the disease [3]. But to date there have been only a few measurements of the fluctuations in vestibular function around the time of the attack. This has been due to two factors. First, the difficulty of testing early MD patients around the time of their attack, which can have highly variable duration: each attack may last from 10 min to hours [2, 3]. Second, the limited range of vestibular tests available and the fact that the usual tests of vestibular function are so demanding that they are not feasible in patients around the time of the attack. However, recently, we published results of a new nondemanding test of otolith function—the n10 of the ocular vestibular-evoked myogenic potential which showed that there are fluctuations in vestibular function, with enhanced dynamic utricular function at the time of the attack compared to quiescence [4]. Here, we wish to address the complementary question as to whether dynamic semicircular canal function fluctuates as auditory and dynamic otolith function does and we present evidence of variations in dynamic semicircular canal function around the time of the MD attack. The development of the video head impulse test (vHIT) has allowed non-demanding objective measures of semicircular canal function [5]. This is a very simple, fast way of measuring dynamic semicircular canal function accurately and has been validated by directly comparing it to simultaneous measures by the ‘‘gold standard’’ search coil test [6]. The gain measurements of the two tests are not significantly different and show very high concordance correlations [6]. With vHIT it is possible to test patients very quickly at short intervals and this kind of easily repeatable, high accuracy, minimally demanding test allows the measurement of the sequential changes in semicircular canal function at the time of the attack. The vHIT test involves the clinician delivering brief, passive, high acceleration head impulses of yaw head rotation unpredictably to the right or left through an angle of about 10 –20 while the patient is instructed to keep looking at an earth-fixed target. The patient wears a set of minimal-slip goggles to which is attached a small lightweight high speed video camera to measure eye position and a 3-d sensor to measure head velocity. We used vHIT to measure the yaw VOR response of patients with evidence of early MD, both at quiescence and during an acute attack. Here, we report that the repeated tests at short intervals show that the VOR response changes substantially around the time of an attack (Fig. 1). One important issue is that the patients for this study were a homogeneous group with early MD (6 subjects, 3 L. Manzari (&) MSA ENT Academy Center Cassino, Via Riccardo da S.Germano 41, 03043 Cassino (FR), Italy e-mail: leonardomanzari@virgilio.it