The effects of hyperbaric oxygen on experimental noise damage to the ears

The use of combined pharmacotherapy and hyperbaric oxygen in the treatment of sudden sensorineural hearing loss

Aim: Sudden sensorineural hearing loss (SSNHL) involves acute unexplained hearing loss, nearly always one-sided of 30dB or greater over at least three contiguous audiometric frequencies. The aetiology of SSNHL is mostly unknown. According to the literature, the causes include vascular, microbial and autoimmune problems. There is still no agreed standard treatment. The aim of the paper was to evaluate the results of combined pharmacotherapy and hyperbaric oxygen therapy in patients with idiopathic sudden deafness. Material/Methods: The study was carried out on 40 patients with SSNHL. The patients were divided into two groups: group I – 24 patients treated with the combined pharmacotherapy and hyperbaric oxygen therapy and group II – 16 patients treated only pharmacologically. The patients from Group 1 were treated in the Centre of Hyperbaric Therapy CREATOR Ltd. in Lodz, Poland. Each patient underwent 15 sessions in a hyperbaric chamber. In all patients, the percentage of hearing loss for the selected frequencies was assessed before and after the therapy according to Sabine and Fowler. Results: The group of 40 patie nts aged from 33 to 77 years (mean 52.4) included 21 females and 19 males. Group I consisted of 24 patients, 11 females and 13 males, group II consisted of 16 patients, 10 females, and 6 males. After therapy, the mean hearing level in all patients improved by 27.14%, in Group I – by 34.34%, in Group II – by 16.3%. Conclusions: Early hyperbaric oxygen therapy combined with steroid therapy improves prognosis and shows good results in sudden hearing loss treatment.

The use of hyperbaric oxygen therapy in acute hearing loss: a narrative review

INTRODUCTION

Acute hearing loss can have a major impact on a patient's life. This holds true for both acute acoustic trauma (AAT) and idiopathic sudden sensorineural hearing loss (ISSHL), two devastating conditions for which no highly effective treatment options exist. This narrative review provides the rationale and evidence for HBOT in AAT and ISSHL.

METHODS

Narrative review of all the literature available on HBOT in acute hearing loss, studies were retrieved from systematic searches on PubMed and by cross referencing.

DISCUSSION

First, the etiological mechanisms of acute hearing loss and the mechanism of action of HBOT were discussed. Furthermore, we have provided an overview of 68 studies that clinically investigated the effect of HBOT in the last couple of decades. For future studies, it is recommend to start as early as possible with therapy, preferably within 48 h and to use combination therapy consisting of HBOT and corticosteroids.

IMPLICATIONS FOR PRACTICE

HBOT has been used quite extensively for acute hearing loss in the last couple of decades. Based on the amount of studies showing a positive effect, HBOT should be discussed with patients (shared decision making) as optional therapy in case of AAT and ISSHL.

Hyperbaric Oxygen Therapy in Acute Acoustic Trauma: A Rapid Systematic Review

In this rapid systematic review, we studied the clinical question, What is the effect of hyperbaric oxygen therapy on hearing thresholds in patients who suffered a recent acute acoustic trauma? After screening for eligible titles and abstracts and extracting duplicates, 6 original research papers could be found. The general methodology of the studies was weak and the differences between these studies were too profound to pool the data, especially because of heterogeneity in adjuvant therapies, follow-up, and treatment protocol. The mean dB of hearing recovery in these studies ranged from 17 to 47 dB in the groups treated with hyperbaric oxygen versus 5 to 46 dB in the groups who did not receive hyperbaric oxygen therapy. We conclude that the effect of hyperbaric oxygen therapy on hearing thresholds in patients with hearing loss caused by a recent acute acoustic trauma remains unclear. A well-designed randomized controlled trial with enough power is advised to answer this clinical question.

Effects of hyperbaric oxygen and dexamethasone on proinflammatory cytokines of rat cochlea in noise-induced hearing loss

HYPOTHESIS

To investigate effects of dexamethasone and hyperbaric oxygen therapy (HBOT) on proinflammatory cytokines and hearing levels in the noise-exposed cochlea of rats.

BACKGROUND

There is an arising concern about negative effects of early initiation of HBOT on hearing in noise-induced hearing loss. Furthermore, effects of HBOT and dexamethasone on cochlear cytokines are not fully elucidated.

METHODS

Twenty-six rats were divided into 3 groups: control, noise, and treatment groups. Five rats served as control group. White noise at 115 dB sound pressure level was applied to the noise group of 4 rats for 10 days. This group was assigned to a positive control group as it was equivalent to treatment groups. The treatment group of 17 rats underwent the same noise exposure, and then, they were divided into 3 groups based on treatment protocol: 5 and 6 rats received HBOT at the third hour and 24th hour after the noise, respectively, and 6 rats received dexamethasone. Auditory brain stem response threshold was measured in all groups before being assigned to the groups, after the noise exposure and right before being killed. Cytokine levels at the cochlear soft tissues were measured using enzyme-linked immunoassay.

RESULTS

Final thresholds (10 dB and 5 dB nHL-normal hearing level) of HBOT-24th hour and dexamethasone groups were significantly better than that of untreated noise group (22.5 dB nHL) (p < 0.05). There was no significant difference between HBOT-24th hour group (10 dB nHL) and dexamethasone group (5 dB nHL) (p > 0.05). IL-6 and IL-1β of HBOT-third hour group (2.30 ng/mg and 185.43 pg/mg) were significantly higher than those of the noise group (0.91 ng/mg and 131.40 pg/mg), dexamethasone group (1.19 ng/mg and 112.29 pg/mg) and HBOT-24th hour group (1.34 ng/mg and 106.69 pg/mg) (p < 0.05). There was no significant difference in IL-6 and IL-1β of HBOT-24th hour group, dexamethasone group, noise group, and control group (p > 0.05). There was no significant difference in TNF-α of the 3 treatment groups, noise group, and control group (p > 0.05).

CONCLUSION

The results showed that the most effective method in the treatment of noise-induced hearing loss was early initiation of dexamethasone therapy. There could be negative effects of HBOT on hearing if it is commenced early after the noise (first 3 h). HBOT treatment, which was started at the 24th hour, was found to be an effective method.

Hyperbaric oxygenation with corticoid in experimental acoustic trauma

Among possible therapies after acute acoustic trauma, hyperbaric oxygenation (HBO) combined with corticoid was found effective in several animal studies. Such evidence was obtained for moderate 20-25 dB losses. The aim of this study was to further assess this therapy for noise-induced hearing losses greater than previously examined. Sixty-five ears from thirty-six adult guinea pigs were used. Acoustically evoked responses from intracranial electrodes chronically implanted bilaterally into the ventral cochlear nucleus were used to assess acoustic sensitivity alterations. Trauma sound was a third-octave noise-band around 8 kHz presented bilaterally at 115 dB SPL for 45 min. One control group received no treatment, one group was treated with HBO only and another with corticoid only both starting within one day post-trauma, two groups were treated with both HBO and corticoid starting for one group within one day post-trauma, and for the second group at 6 days post-trauma. Acoustic thresholds were measured between the 6th and the 16th days after acoustic trauma. Animals treated with HBO alone or corticoid alone did not differ from controls. Combined HBO and corticoid therapy provided significant protection from noise-induced loss of auditory thresholds, especially when started one day post-exposure. Hearing loss reduction induced by HBO combined with corticoid was of similar magnitude (about 10-15 dB) as in previous studies although the induced hearing loss was considerably greater (about 40 dB instead of 20-25 dB).

Effect of hyperbaric oxygen treatment on permanent threshold shift in acoustic trauma among rats

Impulse noise from firearms is a common cause of acute acoustic trauma (AAT). Recently hyperbaric oxygen treatment has become available in many hospitals treating AAT. We exposed 39 Wistar rats to intense impulse noise of 60 shots from the assault rifle (162 dB SPL). After the exposure 15 animals were given hyperbaric oxygen treatment (HBO) by 10 treatment cycles of 90 minutes 100% oxygen in 0.25 MPa, one treatment cycle per day. Four weeks after the exposure the hearing thresholds were measured with auditory brainstem response audiometry at frequencies of 1.0, 2.0, 4.0, 6.0, 8.0 and 10.0 kHz. Characteristics for the resulting noise-induced hearing loss were large variations in its severity not only between animals, but also between the ears of a single animal. The largest permanent threshold shifts were found at 6.0, 8.0 and 10.0 kHz. Most of the HBO-treated animals showed less threshold shift than the non-treated animals. The difference between the HBO group and the control group was only slightly statistically significant (p = 0.067).

Electroencephalographic and evoked potential monitoring in the hyperbaric environment

The purpose of this study was to investigate brain bioelectrical activity during hyperbaric oxygenation by continuous and simultaneous monitoring of electroencephalographic and bimodal (auditory, somatosensory) evoked potentials. Multivariable recordings (electroencephalogram, brainstem auditory evoked potentials, early somatosensory evoked potentials, heart rate, heart rate variability, and transcutaneous partial pressure of oxygen) were measured with a new technique in 12 healthy male volunteers 26 to 52 years old (mean +/- SD, 35.9 +/- 9.5 years). Recordings were obtained while the subjects breathed (1) air at normal atmospheric pressure, (2) 100% oxygen at normal atmospheric pressure, (3) air at 2 atm (10 meters sea water [msw]), and (4) 100% oxygen at 2 atm (10 msw). Spontaneous brain electrical activity, somatosensory evoked potentials, and heart rate variability were not significantly affected during hyperbaric oxygenation, whereas the heart rate showed a significant decrease (paired t test, P less than 0.05). Alterations in brainstem auditory evoked potentials were seen under hyperbaric conditions and did not reach statistical significance (increase of the I-V interpeak latency by paired t test; P less than 0.2). All subjects showed insignificant increases in dominant alpha frequency and decreases in delta frequency under hyperbaric situations.

Complications of hyperbaric oxygen in the treatment of head and neck disease

Hyperbaric oxygen has been advocated in the treatment of many head and neck diseases. Reports of such treatments have described eustachian tube dysfunction as the only complication. A review of patients receiving hyperbaric oxygen for head and neck diseases at The Mount Sinai Medical Center revealed serious complications, which included seizure, stroke, and myocardial infarction. In addition, follow-up study of these patients demonstrated that 11 patients treated for radiation-induced necrosis had an undiagnosed recurrence of cancer.

Hyperbaric oxygen therapy for acute acoustic trauma

We conducted a study on the effect of hyperbaric oxygen therapy on 122 soldiers following acute acoustic trauma. The patients included in this study, after the effect of spontaneous recovery had largely been excluded, were randomly allocated to four treatment groups. The results of our studies show that hyperbaric oxygen therapy shortens the course of healing with respect to high-pitch perception dysacusis. The results of treatment after an observation period of 6 weeks is also more favorable when patients are treated with oxygen when compared to patients given infusions or vasoactive substances. Similarly, the use of hyperbaric oxygen therapy also reduces the frequency of relapse following discharge from hospital. In contrast, the vasoactive substance chosen in our studies (betahistine) failed to have a favorable effect on the course of healing. Our study has also shown that no method can compare with hyperbaric therapy in eliminating tinnitus following acoustic trauma.