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OBJECTIVES: Assess the association of hearing on sex-specific overall mortality and death from acute cardiovascular disease and evaluate if these effects are modulated by postural balance. STUDY DESIGN: Cohort study. SETTING: Otolaryngology department at an academic hospital. METHODS: Patients underwent standard clinical examination, laboratory examination including stabilometry and audiometry. Pure tone average on the best hearing ear was calculated from 0.5, 1, 2, and 3 kHz. Cause of death was retrieved from the Norwegian Cause of Death Registry. RESULTS: A total of 1036 patients (58.8% women) were followed for 26 ± 3 years. In Cox regression analyses for overall mortality adjusted for age, past medical history, and vestibular disease, 10 dB increase in hearing threshold was associated with a 14% increase in mortality among men (hazard ratio 95% confidence interval: 1.02-1.28, P = .02), but no significant association was seen between hearing and mortality in women (0.92-1.15, P = .60). The same analyses for acute cardiovascular death found that a 10 dB increase in hearing threshold was associated with a 57% increase in hazard ratio in men (1.21-2.05, P < .001), but no significant effect of hearing on survival was seen in women (P = .71). Adjusting for postural balance did not change the association between hearing and mortality. CONCLUSION: This study finds hearing threshold is associated with overall mortality and acute cardiovascular death among men, with no such association observed among women. Our findings indicate important differences between men and women and suggest that such differences should be taken into consideration in audiological research.

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INTRODUCTION: Inner ear barotraumas and decompression sickness (DCS) may cause acute vestibular symptoms in divers. The result may be irreversible damage to the vestibular end organs or their central connections. We examined a group of offshore divers in order to find out how many divers experience vestibular symptoms later in life and how this was related to occupational history and objective findings. METHODS: A questionnaire was sent to 230 offshore divers (mean age 52 yr) and 166 age-matched non-diving controls. Most of the divers had retired from diving. A subgroup (n=96) of the divers was referred for examination, including a clinical otoneurological examination, electronystagmography, bithermal caloric tests, and platform posturography. In addition, 42 of the controls were examined. RESULTS: The prevalence of dizziness (28%), spinning vertigo (14%), and unsteady gait (25%) was significantly higher in divers than controls (p < 0.0005). These symptoms were strongly associated with a previous history of DCS, particularly type I, which was reported by 61% of the divers. Symptoms were less strongly associated with the number of dives. In referred divers with dizziness, the prevalence of abnormal postural sway, nystagmus, canal paresis, or pathological smooth pursuit was 32%, 9%, 7%, and 11%, respectively. DISCUSSION: Reasons for the high prevalence of vestibular symptoms among the divers are discussed. The high exposure to DCS is probably an important factor.

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BACKGROUND: The effects on the postural system of saturation diving to shallow and medium depths have not previously been adequately tested. The purpose of this study was to investigate whether postural function is affected by a moderate hyperbaric exposure, and whether any deterioration is correlated with the presence of intravascular bubbles. HYPOTHESIS: Postural control and the vestibulo-ocular reflex are not affected during heliox saturation diving to 5 meters of seawater (msw). At greater depths, an effect may occur. METHODS: Postural control was tested with the subjects standing on a static balance platform before, during, and after onshore experimental saturation chamber dives to 5 msw heliox, 20 msw air, and to 100 msw heliox. Standard caloric testing with electronystagmography was performed before and after the heliox dives. Cardiac ultrasound and Doppler monitoring were used to detect possible venous gas emboli (VGE) during decompression in the heliox dives. RESULTS: During the heliox exposure to 5 msw, no significant change in body sway was found. However, a significant change in body sway was found during an air dive to 20 msw and during the 100 msw heliox exposure. Caloric responses were unchanged immediately post-dive. After decompression from 5 msw, VGE were detected in two divers. During the 100 msw exposure, one case of VGE was observed. CONCLUSIONS: Exposure to hyperbaric heliox conditions corresponding to 5 msw, did not influence postural control significantly, while exposure to 100 msw heliox, and air diving to 20 msw, did. Although VGE were detected in the heliox dives, we could not find any correlation between this observation and postural instability.

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