Inner ear dysfunction of uncertain origin: A multidisciplinary approach could give something more

Reassessment of oxidative stress in idiopathic sudden hearing loss and preliminary exploration of the effect of physiological concentration of melatonin on prognosis

Background and purpose

The pathogenesis of idiopathic sudden sensorineural hearing loss (ISSNHL) is still unclear, and there is no targeted treatment. This research aimed to verify the role of oxidative stress in ISSNHL and explore whether melatonin has a protective effect on hearing.

Materials and methods

A total of 43 patients with ISSNHL and 15 healthy controls were recruited to detect the level of melatonin, reactive oxygen species (ROS), and total antioxidant capacity (TAC) in the blood and compared before and after treatment. Multivariate logistic regression models were performed to assess the factors relevant to the occurrence and improvement of ISSNHL.

Results

The patients with ISSNHL showed significantly higher ROS levels than controls (4.42 ± 4.40 vs. 2.30 ± 0.59; p = 0.031). The levels of basal melatonin were higher (1400.83 ± 784.89 vs. 1095.97 ± 689.08; p = 0.046) and ROS levels were lower (3.05 ± 1.81 vs. 5.62 ± 5.56; p = 0.042) in the effective group as compared with the ineffective group. Logistic regression analysis showed that melatonin (OR = 0.999, 95% CI 0.997-1.000, p = 0.049), ROS (OR = 1.154, 95% CI 1.025-2.236, p = 0.037), and vertigo (OR = 3.011, 95% CI 1.339-26.983, p = 0.019) were independent factors associated with hearing improvement. Besides, the level of melatonin (OR = 0.999, 95% CI 0.998-1.000, p = 0.023) and ROS (OR = 3.248, 95% CI 1.109-9.516, p = 0.032) were associated with the occurrence of ISSNHL.

Conclusion

Our findings may suggest oxidative stress involvement in ISSNHL etiopathogenesis. The level of melatonin and ROS, and vertigo appear to be predictive of the effectiveness of hearing improvement following ISSNHL treatment.

Low-grade albuminuria is associated with hearing loss in non-diabetic US males: A cross-sectional analysis of 1999-2004 national health and nutrition examination survey

High levels of albuminuria have been demonstrated to associate with hearing loss in non-diabetic people, while the clinical impact of low-grade albuminuria has attracted less attention. This cross-sectional population-based study aimed to examine whether hearing loss in non-diabetic United States (US) adults is independently associated with low-grade albuminuria or reduced estimated glomeruli filtration rate (eGFR).A total of 2518 participants aged 20 to 69 years were selected from the US National Health and Nutritional Examination Survey database. Participants with diabetes or high-grade albuminuria were excluded. Hearing loss was assessed using low-frequency pure-tone average (LFPTA) thresholds (0.5, 1.0, 2.0 kHz) and high-frequency pure-tone average (HFPTA) thresholds (3.0, 4.0, 6.0, 8.0 kHz). Logistic and linear regression analyses were used to evaluate associations between renal function indicators and hearing loss.The median age of included participants was 37.4 years, and 55% of them were female. Multivariate analysis revealed that participants with urinary albumin-to-creatinine ratio (UACR) in the highest tertile had a significantly higher risk of hearing loss (OR, 1.79; 95% CI, 1.01-3.19) and higher HFPTA thresholds (β: 2.23; SE: 0.77). Participants with eGFR <60 mL/min/1.73 m had higher LFPTA thresholds (β: 4.31; SE: 1.79). After stratification by sex, a significant risk remained only for males in the highest UACR tertile, with 2.18 times the risk of hearing loss (95% CI, 1.06-4.48).Non-diabetic US males with low-grade albuminuria are at increased risk of hearing loss, independent of eGFR.

Inner ear symptoms: can we use them to approach cardiovascular diseases?

Sensory organs are programmed to detect external stimuli, and inform about possible threats. In general, they are characterized by a complex architecture, a highly energy-requiring function, a peripheral location and a vascular supply depending on a terminal circulation usually under systemic control. Their function may be highly sensitive to more general disorders primarily involving other organs or physiological systems. Consequently, the onset of transient or persistent symptoms of impairment of sensory organs might be the expression of abnormalities in the integrity of more general systems, especially in the elderly population. In the otologic area, despite the availability of evidence supporting the negative impact of some systemic conditions negatively affecting the local blood supply at the labyrinth level, the possibility that the inner ear can reveal the presence of sub-clinical, non-otologic disorders has never been the topic of a constructive investigation. The present review summarizes the preliminary available evidence suggesting a possible negative impact of early systemic hemodynamic changes on the function of the inner ear, as well as the possibility that some audiological symptoms may play some role in the early detection of cardiovascular diseases. In particular, we hypothesize that some cardiovascular diseases may cause an impairment in correct labyrinthine function as a result of a negative interaction between systemic hemodynamic changes, a reflex activation of the autonomic nervous system, and a local vascular response. A multidisciplinary approach to the interpretation of inner ear disorders may increase the possibility of an earlier recognition and understanding of systemic dysfunctions in clinical practice.

Diuretics in Meniere disease: a therapy or a potential cause of harm?

Despite the lack of clear evidence for their effectiveness in treating vertigo, tinnitus, hearing loss and aural fullness, diuretics, represent a common treatment for Meniere disease (MD), as they are supposed to decrease volume and pressure in the endolymphatic partition of the labyrinth. Our group have outlined the possibility of an adverse effect on inner ear function derived from an abrupt lowering of blood pressure: a subsequent exaggerated vasomotor response inducing local ischemia could be responsible for more or less permanent damage. The inner ear, owing both to its terminal vascular supply and to the necessity of a steady metabolism, seems a reliable target for any hemodynamic imbalance that acutely affect its perfusion. In our opinion, the complexity of the inner ear anatomy and function argues against the usefulness of diuretics to reduce endolymphatic volume, in analogy to their effect on the volemia: too many active mechanisms and "buffer" systems are involved in the labyrinth. Even considering that the finding of mean low pressure values is relatively common in subjects with MD, an attempt should be to maintain a stable blood perfusion to the labyrinth; in fact, an abrupt decrease in systemic blood pressure can trigger an adverse sympathetic reaction and transmit misleading information to the cochlear vasopressin receptors.

Tinnitus in elderly patients and prognosis of mild-to-moderate congestive heart failure: a cross-sectional study with a long-term extension of the clinical follow-up

BACKGROUND

The complex mechanism responsible for tinnitus, a symptom highly prevalent in elderly patients, could involve an impaired control of the microcirculation of the inner ear, particularly in patients with poor blood pressure control and impaired left ventricular (LV) function.

METHODS

In order to define the relationship between the presence of tinnitus and the severity and clinical prognosis of mild-to-moderate chronic heart failure (CHF) in a large population of elderly patients (N = 958), a cross-sectional study was conducted with a long-term extension of the clinical follow-up. Blood pressure, echocardiographic parameters, brain natriuretic peptide (BNP), hospitalization, and mortality for CHF were measured. Multivariate logistic regression analysis was used to assess the association between the presence of tinnitus and some of the prognostic determinants of heart failure.

RESULTS

The presence of tinnitus was ascertained in 233 patients (24.3%; mean age 74.9 ± 6 years) and was associated with reduced systolic and diastolic blood pressure (123.1 ± 16/67.8 ± 9 vs 125.9 ± 15/69.7 ± 9; P = .027/P = .006), reduced LV ejection fraction (LVEF%; 43.6 ± 15 vs 47.9 ± 14%, P = .001), and increased BNP plasma levels (413.1 ± 480 vs 286.2 ± 357, P = .013) in comparison to patients without symptoms. The distribution of CHF functional class was shifted toward a greater severity of the disease in patients with tinnitus. Combined one-year mortality and hospitalization for CHF (events/year) was 1.43 ± 0.2 in patients with tinnitus and 0.83 ± 0.1 in patients without tinnitus, with an adjusted hazard ratio (HR) of 0.61 (95% confidence interval (CI): 0.37 to 0.93, P <.002).

CONCLUSIONS

Our preliminary data indirectly support the hypothesis that tinnitus is associated with a worse CHF control in elderly patients and can have some important clinical implications for the early identification of patients who deserve a more aggressive management of CHF.

Meniere's disease: update of etiopathogenetic theories and proposal of a possible model of explanation

Meniere's Disease (MD) is an affection consisting of an association of sensorineural hearing loss, tinnitus and vertigo initially presenting by crises. A review of the most considered possible causative factors and pathophysiologic interpretations allows us to underline the uncertainties which still exist about the genesis of this illness. We propose a mechanistic model based on the effect of a haemodynamic imbalance leading to transient ischaemia which could have an effect on the pH of the inner ear as well as on the work of the inner ear proton pumps. It is hypothesized that under ischaemic conditions and consequent metabolic acidity a preserved proton pump activity can generate an overload of anions in the endolymphatic partition, which is a closed system, thus resulting in an enhancement of osmolarity and consequently in the formation of a hydrops resulting in the development of fluctuating hearing loss, tinnitus and vertigo which characterize Meniere's Disease.

The effects of the Chinese herbal medicine EMF01 on salicylate-induced tinnitus in rats

AIM OF THE STUDY

Traditional Chinese medicine (TCM) has been reported to successfully alleviate tinnitus, although well-controlled studies have not been conducted. In this study, we attempted to test a TCM, Er Ming Fang (EMF01) containing Rehmannia glutinosa, Cornus officinalis, Salvia mittiorrhiza, Pueraria, Schisandra chinensis, Poria cocos and Platycodon grandiflorum, on salicylate-induced tinnitus in rats, using a conditioned lick suppression paradigm.

MATERIALS AND METHODS

A pilot study examined the effect of 8.75 g/kg and 17.5 g/kg EMF01 (delivered by oral gavage for 20 days) and showed a slight decrease in the suppression ratio (SR) in the 8.75 g/kg group. In order to confirm the possible effect of EMF01 on tinnitus at 8.75 g/kg, a further study was carried out with a larger sample size.

RESULTS

While there were statistically significant differences between the treatment groups, post hoc tests revealed that EMF01 did not have any significant effect on salicylate-induced tinnitus.

CONCLUSIONS

While this study does not support the efficacy of EMF01 in the treatment of salicylate-induced tinnitus, further studies should be conducted to determine if it alleviates tinnitus associated with acoustic trauma.

Tinnitus as a warning for preventing vasovagal syncope

It has been widely outlined by our group the possibility that a sufferance of the inner ear can take place as a consequence of hemodynamic imbalance which could affect young and healthy people and recognize a merely functional origin. As reported in previous papers, an altered reaction of the autonomic nervous system could actually jeopardize the labyrinthine perfusion even in absence of other damages. From this standpoint, the hypothesis that a hyperactivity of the vagal response to an acute sympathetic drive may result in an inner ear sufferance deserves to be explored. A mechanism which appears to fit to this model is represented by the Bezold-Jarisch reflex (BJR), which is considered to be responsible for vasovagal syncope and is characterized by a dynamic reasonably compatible with our findings. According to these premises, especially considering that the inner ear has a less active protective mechanism against ischemia as compared to brain, in predisposed subjects tinnitus, when considered as an initial symptom of inner ear hypoperfusion, can represent a warning able to prevent the lack of consciousness related to the syncope.