The role of diet in vulnerability to noise-induced cochlear injury and hearing loss.

The influence of dietary nutrient intake on the onset and trajectory of hearing loss during aging and in mediating protection from challenges such as noise is an important relationship yet to be fully appreciated. Dietary intake provides essential nutrients that support basic cellular processes related to influencing cellular stress response, immune response, cardiometabolic status, neural status, and psychological well-being. Dietary quality has been shown to alter risk for essentially all chronic health conditions including hearing loss and tinnitus. Evidence of nutrients with antioxidant, anti-inflammatory, and anti-ischemic properties, and overall healthy diet quality as otoprotective strategies are slowly accumulating, but many questions remain unanswered. In this article, the authors will discuss (1) animal models in nutritional research, (2) evidence of dietary nutrient-based otoprotection, and (3) consideration of confounds and limitations to nutrient and dietary study in hearing sciences. Given that there are some 60 physiologically essential nutrients, unraveling the intricate biochemistry and multitude of interactions among nutrients may ultimately prove infeasible; however, the wealth of available data suggesting healthy nutrient intake to be associated with improved hearing outcomes suggests the development of evidence-based guidance regarding diets that support healthy hearing may not require precise understanding of all possible interactions among variables. Clinical trials evaluating otoprotective benefits of nutrients should account for dietary quality, noise exposure history, and exercise habits as potential covariates that may influence the efficacy and effectiveness of test agents; pharmacokinetic measures are also encouraged.

Atorvastatin in the management of tinnitus with hyperlipidemias.

OBJECTIVE: To determine the role of atorvastatin in management of tinnitus in patients with hyperlipidemia. STUDY DESIGN: Quasi-experimental study. PLACE AND DURATION OF STUDY: ENT Department, Combined Military Hospital, Rawalpindi, from July 2011 to August 2012. METHODOLOGY: Ninety eight patients of tinnitus with sensorineural hearing loss having hyperlipidemia were included in the study. Their pre-therapy serum cholesterols were measured, and tinnitus scores were recorded on a 'Tinnitus handicap questionnaire'. They were administered tablet atorvastatin 40 mg once daily with low fat diet for 8 months. After 8 months of therapy, patients were purposefully divided into responsive and unresponsive group depending on serum cholesterol levels. Post therapy serum cholesterol levels and tinnitus scores were also recorded after 8 months and compared with pre-therapy records. RESULTS: Serum cholesterol came to within normal limits in 51 (52%) patients (responsive group), while it remained high in 47 (48%) patients (unresponsive group). Improvement in tinnitus score in the responsive group was seen in 36 (70.5%) patients and in 2 (4.2%) patients of the unresponsive group. Improvement in tinnitus scores was compared in the two groups using Fisher's exact test and were found to be statistically better in the responsive group (p < 0.001). CONCLUSION: Tinnitus, in patients having hyperlipidemia, can be successfully dealt with by treating hyperlipidemia with lipid lowering agent atorvastatin.

Nutrient-enhanced diet reduces noise-induced damage to the inner ear and hearing loss.

Oxidative stress has been implicated broadly as a cause of cell death and neural degeneration in multiple disease conditions; however, the evidence for successful intervention with dietary antioxidant manipulations has been mixed. In this study, we investigated the potential for protection of cells in the inner ear using a dietary supplement with multiple antioxidant components, which were selected for their potential interactive effectiveness. Protection against permanent threshold shift (PTS) was observed in CBA/J mice maintained on a diet supplemented with a combination of ß-carotene, vitamins C and E, and magnesium when compared with PTS in control mice maintained on a nutritionally complete control diet. Although hair cell survival was not enhanced, noise-induced loss of type II fibrocytes in the lateral wall was significantly reduced (P < 0.05), and there was a trend toward less noise-induced loss in strial cell density in animals maintained on the supplemented diet. Taken together, our data suggest that prenoise oral treatment with the high-nutrient diet can protect cells in the inner ear and reduce PTS in mice. The demonstration of functional and morphologic preservation of cells in the inner ear with oral administration of this antioxidant supplemented diet supports the possibility of translation to human patients and suggests an opportunity to evaluate antioxidant protection in mouse models of oxidative stress-related disease and pathology.

Low-cholesterol diet and antilipid therapy in managing tinnitus and hearing loss in patients with noise-induced hearing loss and hyperlipidemia.

The aim of our study was to outline the prevalence of hyperlipidemia in patients who had high-frequency hearing loss and tinnitus due to noise exposure. We investigated the role of a low-cholesterol diet and antihyperlipidemic therapy to alleviate the severity of tinnitus and possibly promote hearing gain after therapy in patients with acoustic trauma. Forty-two hyperlipidemic patients with subjective tinnitus and hearing loss due to noise exposure were enrolled for the study. We placed patients on a low-cholesterol diet or antihyperlipidemic therapy and followed them for up to 24 months; then we designated two groups as either "unresponsive" (n = 22; no response to either of the therapies and still experiencing hyperlipidemia) or "responsive" (n = 20; lower cholesterol or triglyceride levels). We then compared tinnitus scores and hearing levels in the two groups. The difference between tinnitus scores in the unresponsive and responsive groups and the change in tinnitus scores before and after therapy in the responsive group were significant. When we compared self-rated tinnitus severity results in two groups after therapy, we found the difference was significant (p < .05). The difference between average air-conduction thresholds at high frequencies after the treatment in the two groups was also significant. The incidence of hyperlipidemia is high among patients with noise-induced hearing loss, and significant improvement by way of lowered tinnitus intensity and higher frequencies in average hearing thresholds can be achieved after lowering the serum lipid level.