Sudden Sensorineural Hearing Loss: Results of intratympanic steroids as salvage treatment

Abstract

Objective

The aim of the present study was to verify the efficacy and the safety of intratympanic dexamethasone to treat sudden sensorineural hearing loss as salvage therapy.

Materials and methods

A prospective study was conducted on patients affected by idiopathic sudden hearing loss who were treated before with some systemic therapy, but without recovery of the hearing The patients able to undergo the study, but who refused salvage treatment were considered as control group. A solution of Dexamethasone 4 mg/ml was then injected through the posterior–inferior quadrant filling completely the middle ear. The follow-up in the following 6 months included an audiogram every month.

Results

The number of patients treated with salvage therapy was 36. The patients who refused treatment were further 10. The salvage treatment was done with a mean delay of 24.3 days from the onset of symptoms. Mean hearing threshold after the onset of sudden hearing loss at PTA was 66.5 dB. After the failed treatment the mean PTA was 59.6 dB. The mean PTA after the intratympanic steroid administration was 46.8 dB, with a mean improvement of 12.8 dB. No hearing change was noted in the 10 patients who refused salvage therapy. The patients that assumed systemic steroid as first therapy showed a better PTA threshold after the salvage intratympanic treatment (p < 0.01). A significant difference (p < 0.05) of hearing recovery was evidenced between non-smoker patients and those with smoking habit.

Conclusions

Our data showed that a salvage treatment with intratympanic dexamethasone should be suggested to all patients who failed the first systemic treatment. The systemic steroid therapy done before the salvage treatment seems to exert a protective role for the inner ear, as shown by our series. On the contrary the smoke habit is a negative prognostic factor in the hearing recovery.

1 Introduction

The loss of hearing of at least 30 dB over at least 3 contiguous frequencies occurring within 3 days or less is known as Sudden Sensorineural Hearing Loss (SSHL). In more than 90% of patients, the true cause of the hearing loss is not discovered, constituting an idiopathic disease. The estimated incidence of such disease is 5 to 20 cases per 100,000 annually . However the exact incidence is underestimated, because many patients who recover early (within first few days) are unlikely to seek medical care . The rate of spontaneous recovery is approximately between 32% and 70% which encourage some otologists not to treat SSHL patients .

The lack of consensus in the management of SSHL is due to difficulty in finding the true etiology of the deafness. Numerous treatments have been described: steroids, antiviral drugs, osmotic diuretics, anticoagulants, vasodilators, hyperbaric oxygen, carbogen; most therapies showed some benefits in restoring hearing notwithstanding the lack of robustness of the data.

The most widely employed drugs in the management of SSHL are steroids that are administered as a single agent or associated with other drugs. Several placebo-controlled trials reported encouraging results in terms of recovering of hearing loss , although other authors discussed such efficacy in the treatment of SSHL .

Although the treatment is started within a reasonable time after onset of the hearing loss, the result is not always achieved and about 30%–40% of patients have no benefits after systemic treatment.

The aim of the present study was to verify the efficacy and the safety of intratympanic dexamethasone (ITD) to treat SSHL patients as salvage therapy after other treatments.

2 Materials and methods

A prospective study was conducted on patients affected by idiopathic SSHL who were treated before with some systemic therapy, but without recovery of the hearing (less than 10 dB of PTA threshold recovery). The patients included were referred to our departments from January 2011 to December 2011. The inclusion criteria were: an SSHL of at least 30 dB across 3 contiguous frequencies over a period of 3 days and a previous systemic treatment that gave no recovery of hearing. The patients with the following characteristic were excluded: history of middle ear pathology, previous intratympanic treatments administered elsewhere for the same disease. The patient evaluation included: thorough history, otoscopy, bedside peripheral vestibular system examination, pure tone audiometry (repeated weekly) and MRI of internal auditory canal and cerebello-pontine angle. History detailed: onset of hearing loss, otological symptoms related with hearing loss, drugs consumed in the past days and presence of others systemic diseases. The bedside examination was done for spontaneous and positional nystagmus, Romberg test, Fukuda test, Halmagyi test and Head Shaking test.

The patients able to undergo the study, but who refused salvage treatment were considered as control group.

Intratympanic injection was done in supine position with the head rotated to 45° to the unaffected side. Under microscope a myringotomy was done in the anterior–inferior quadrant of the tympanic membrane in order to allow the exit of the air in the middle ear during drug injection. A solution of Dexamethasone 4 mg/ml was then injected through the posterior–inferior quadrant filling completely the middle ear. The patient maintained the position of the head for 20 min and was instructed to avoid swallowing, speaking and movements of the head. The intratympanic injection was repeated five times every two days.

An audiogram was done weekly during the treatment protocols in both the groups.

The follow-up in the following 6 months included an audiogram every month.

Patients lost during the follow-up and with evidence of retrocochlear disease at MRI (i.e.: vestibular schwannoma) were excluded from the analysis.

A response to the treatment was considered if a change was recorded in PTA by calculating ΔPTA as the difference between the PTA before salvage treatment and the last PTA recorded during follow-up (at least after two months).

Data were entered in a database created within EpiInfo 3.5.1 software. All the data were analyzed using the R statistical software package. Absolute and relative frequencies were calculated for qualitative variables, while quantitative variables were summarized as mean (± standard deviation and range). Categorical variables were analyzed using the chi-square test (Mantel–Haenszel). Odds ratio (OR) with 95% confidence intervals (95% CIs) were also calculated. Differences in means were compared with the Student t-test. All variables found to have a statistically significant association (two-tailed p -value < 0.05) with improved PTA in the univariate analysis were included in a multivariate regression model. The significance level chosen for all analysis was 0.05, two-tailed. All patients signed an informed consent before the treatment and our Review Boards approved the present study.