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Objectives: The purpose of the present study was to describe experiences of disabilities and factors affecting daily life from the perspective of adult persons with severe-to-profound hearing impairment in combination with severe vision impairment. Furthermore, the study also investigated which kind of support individuals with dual sensory loss received, and their experiences as citizens in the society. Methods: Semi-structured qualitative interviews were performed, analyzed, and categorized using content analysis. Results: Fourteen interviews were performed, with equal number of both sexes. Mean age was 70.1 years (47–81 years). Analysis of the data resulted in 22 categories, six sub-themes and two main themes. Two main themes emerged as Isolation and The Ability to control one’s own daily life. Surprisingly, most of the participants did not think of their vision and hearing impairment as a combined disability. The interviews showed various kind of strategies to handle daily life. The Deafblind-team unit was reported to offer excellent health care. Companion services for persons with disabilities proved to have become more difficult to get support from and created lack of independence and control over their own lives. However, it was also obvious that the participants felt a positive outlook on life and were more solution-oriented in order to adjust their everyday life to their lifesituation. Conclusions: The combination of vision and hearing impairment demonstrated isolation, and the respondents in the study have a need of support in everyday lives. At the same time, they struggle to have the ability to control their own lives.

OBJECTIVES: The purpose of this longitudinal twin study was to explore the effect of tinnitus on hearing thresholds and threshold shifts over two decades and to investigate the genetic contribution to tinnitus in a male twin cohort (n = 1114 at baseline and 583 at follow-up). The hypothesis was that participants with faster hearing deterioration had a higher risk for developing tinnitus and there is an underlying role of genetic influences on tinnitus. DESIGN: Male mono- and dizygotic twin pairs, born between 1914 and 1958 were included. Mixed models were used for comparison of hearing threshold shifts, adjusted for age. A co-twin comparison was made within pairs discordant for tinnitus. The relative influence of genetic and environmental factors was estimated by genetic modeling. RESULTS: The overall prevalence of tinnitus was 13.5% at baseline (x age 50) and 34.4% at follow-up (x age 67). The overall incidence proportion was 27.8%. Participants who reported tinnitus at baseline or at both time points were older. At baseline, the hearing thresholds differed between tinnitus cases and controls at all frequencies. New tinnitus cases at follow-up had the greatest hearing threshold shift at the high-frequency area compared with the control group. Within pairs, the tinnitus twin had poorer hearing than his unaffected co-twin, more so for dizygotic than monozygotic twin pairs. The relative proportion of additive genetic factors was approximately 0.40 at both time points, and the influence of individual-specific environment was 0.56 to 0.61. The influence of genetic factors on tinnitus was largely independent of genetic factors for hearing thresholds. CONCLUSIONS: Our hypotheses were confirmed: The fastest hearing deterioration occurred for new tinnitus cases. A moderate genetic influence for tinnitus was confirmed.

OBJECTIVE: The aim was to investigate the influence of environmental exposures on hearing loss in a twin cohort. STUDY SAMPLE: Male twins born 1914-1958, representing an unscreened population, were tested for hearing loss at two occasions, 18 years apart. DESIGN: Clinical audiometry and a questionnaire were performed at both time points in this longitudinal study. Noise and solvent exposure were assessed using occupational work codes and a job exposure matrix. Hearing impairment was investigated using two different pure tone averages: PTA4 (0.5, 1, 2, and 4 kHz) and HPTA4 (3, 4, 6, and 8 kHz). RESULTS: Age affected all outcome measures. Noise exposure between time point one and two affected the threshold shifts of PTA4 and HPTA4 more in participants with a pre-existing hearing loss at time point one. Lifetime occupational noise exposure was a risk factor especially for the low-frequency hearing threshold PTA4. Firearm use was a statistically significant risk factor for all outcome measures. CONCLUSIONS: Pre-existing hearing loss can increase the risk of hearing impairment due to occupational noise exposure. An increased risk for NIHL was also seen in the group with exposures below 85 dB(A), a result that indicates awareness of NIHL should be raised even for those working in environments where sound levels are below 85 dB(A).

The German waltzing guinea pig is a strain of animals expressing deafness and severe balance disorders already at birth. The mutation arose spontaneously in a breeding facility in Germany and as the affected animals show a characteristic waltzing behavior, the strain is named the German waltzing guinea pig. The strain is presently bred only at Karolinska Institutet. The hereditary inner car impairment has a recessive mode of inheritance and the strain thus produces not only affected homozygotes but also symptom-free heterozygotes and fully normal offspring. The outcome depends solely on the genotype of the parents. The beterozygotes, which have obtained the "waltzing" gene from one parent only, have normal hearing and no balance dysfunction. The heterozygous animals appear normal but will, in turn, carry the genetic defect to the next generation. The present thesis is focused on these animals. Noise and ototoxic drugs are well known stress factors that interfere negatively with the hearing organ in both humans and animals, causing hearing impairment. However, the inter-individual variability in susceptibility to auditory stress factors is surprisingly large, most likely due to different genetic predisposition. In this study heterozygous animals of the German waltzing guinea pig, animals carrying a genetic defect known to cause severe hearing impairment, were used to study how an unexplored gene for deafness interacts with the auditory stress agents; noise exposure and the ototoxic drugs gentamicin and cisplatin. Animals were exposed to both narrowband as well as broadband noise at different ages and hearing threshold were conducted using ABR. Heterozygote animals of the German waltzing guinea pigs showed less threshold shifts compared to control strains. Old animals were less affected of the noise trauma than younger animals. To explore the hypothesis that the efferent system contribute to the protection of the inner ear against noise trauma, measurements using the

Precise, non-invasive determination of the aetiology and site of pathology of inner ear disorders is difficult. The aim of this study was to describe an alternative method for inner ear visualization, based on local application of the paramagnetic contrast agent gadolinium. Using a 4.7 T MRI scanner, high contrast images of all four cochlear turns were obtained 3.5 h after placing gadolinium on the round window membrane. Gadolinium cleared from the cochlea within 96 h. Auditory brainstem response measurements performed on a separate group of animals showed no significant threshold shifts after the application, indicating that gadolinium is non-toxic to the guinea pig cochlea.