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Objective Metabolic changes that occur in diabetes mellitus (DM) can interfere with the energy supply for the metabolic active inner ear, resulting in vestibular impairments. The purpose of this study was to evaluate the effects of type 1 DM on the vestibular system using a vestibular test battery. Methods Vestibular function of fifteen asymptomatic type 1 DM patients with a mean age of 28 years (SD= 5.80) and 16 healthy controls with a mean age of 26 years (SD = 2.86), respectively, was assessed using video-head impulse test (vHIT), ocular and cervical vestibular evoked myogenic potential (o/cVEMP), and subjective visual vertical and horizontal (SVV/SVH). Results vHIT response was pathological, in approximately 6.66% of canals. The peak-to-peak p1-n1 amplitude in cVEMP and p1 latency of oVEMP were significantly smaller in the left ear (p = .018) and lengthened in both ears (p = .004) of DM participants compared to the healthy group, respectively. The mean deviation of dynamic SVV (Opto +40/s) was significantly increased (p = .022). Conclusion Asymptomatic DM can influence the vestibular system, especially the otolith organs, indicating the presence of subclinical vestibular dysfunction (VD) prior to the onset of vestibular manifestations, which can be detected using appropriate vestibular tests. Furthermore, DM might have selective or chronological order effects on the human vestibular system, with the otolith system damage preceded the semicircular canals. Thus, early and periodic vestibular assessment of DM patients for detecting possible latent VD and preventing further problems is advisable. However, further clinical studies are required.

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BACKGROUND: Auditory cues might play a role in postural control. OBJECTIVE: The primary aim of this study was to investigate the association between white noise and head-shake (HS) related changes in postural sway. METHODS: Fifty healthy adults underwent Synapsys Posturography System (SPS) evaluation. The posturography (PG) evaluation consisted of two protocols: sensory organization test (SOT) and SOT with head-shake (HS) (HS-SOT). The standard SOT protocol of SPS involves a battery of six postural conditions. In the current study, participants underwent only four SOT conditions. The participants were asked to stand barefoot on the SPS platform (static platform and foam). The SOT standing conditions were as follow: (1) firm surface (force platform only) with eyes open (SOT1); (2) firm surface with eyes closed (SOT2); (3) foam surface (which was positioned on the force platform) with eyes open (SOT4); and (4) foam surface with eyes closed (SOT5). For the HS-SOT protocol, we asked the participants to move their heads left and right (i.e., yaw head rotation) in the mentioned SOT conditions. Each postural condition was 10 seconds long. Both SOT and HS-SOT postural conditions were conducted across the two hearing modes of silence and noise. To achieve our aims, comparison of sway parameters between SOT and HS-SOT, and between hearing modes were considered. RESULTS: White noise was associated with a reduction in postural sway. The reduction observed in sway area, sway amplitude, and sway frequency. Moreover, HS significantly increased postural sway in all HS-SOT conditions compared to their SOT equivalents (i.e., HS-SOT1 compared to SOT1, etc.). The presence of white noise was associated with a decrease in the HS-related increase in postural sway. CONCLUSIONS: Considering the results, this study adds to the body of literature suggesting that white noise contributes to postural control, and the implications of this for rehabilitation need to be further investigated.

Background and Aim: Vibration is a method for stimulating the vestibular system. This met­hod can unmask asymmetry between two vesti­bular systems (such as unilateral peripheral ves­tibular disorders). The occurrence of vibration-induced nystagmus (VIN) in healthy subjects can affect the diagnosis of patients with uni­lateral peripheral vestibular disorders. Thus, the evaluation of VIN in healthy subjects is critical to help the diagnosis of unilateral peripheral vestibular disorders. Methods: This study was carried out on 72 hea­lthy subjects (mean ± SD age: 27.12 ± 4.97 years) in the Auditory and Balance Clinic of Rofeideh Rehabilitation Hospital. Vibration sti­mulation with a frequency of 30 and 100 Hz was used on mastoid and posterior cervical mus­cles (PCMs) and simultaneously eye movements were recorded and analyzed using videonystag­mography. Results: The mastoid vibration with a frequ­ency of 30 and 100 Hz, respectively produced VIN in 16.67% and 27.78% of subjects and VIN observed in PCMs vibration with a frequency of 30 and 100 Hz in 4.17% and 9.72% of the subjects. Conclusion: The occurrence of VIN in healthy subjects was more probable with mastoid vib­ration in 100 Hz. In this study, VIN was pre­dominantly horizontal, its direction was toward the stimulated side, and its slow phase velocity was lower than 5 deg/s. These criteria could be used for differentiation between normal and abnormal subjects.