Editorial Open Access
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Otorhinolaryngol. May 28, 2015; 5(2): 41-43
Published online May 28, 2015. doi: 10.5319/wjo.v5.i2.41
Diagnosis and treatment of sudden sensorineural hearing loss
Tsutomu Nakashima
Tsutomu Nakashima, Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
Author contributions: Nakashima T solely contributed to this work.
Conflict-of-interest: None.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Tsutomu Nakashima, MD, PhD, Department of Otorhinolaryngology, Nagoya University Graduate School of Medicine, 65, Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. tsutomun@med.nagoya-u.ac.jp
Telephone: +81-52-7442323 Fax: +81-52-7442325
Received: January 5, 2015
Peer-review started: January 7, 2015
First decision: February 7, 2015
Revised: February 23, 2015
Accepted: April 16, 2015
Article in press: April 20, 2015
Published online: May 28, 2015

Abstract

Nationwide epidemiological surveys of idiopathic sudden sensorineural hearing loss (SSNHL) have been performed five times by the Research Committee of the Ministry of Health and Welfare or the Ministry of Health, Welfare and Labour in Japan. These surveys included patients who had SSNHL in 1972, 1987, 1993, 2001, and 2012. Using the criteria for the grading of hearing loss in SSNHL or the criteria for grading the degree of hearing recovery after SSNHL established by the Research Committee, we compared the outcomes of SSNHL between the five nationwide surveys. The results revealed that the outcomes of SSNHL have not changed in the past 40 years. In 1972, 88% of patients received steroids, but none received prostaglandin E1 (PGE1). The use of PGE1 has increased since the 1980s, but its effect on SSNHL may not be significant. Intratympanic steroid injection has been introduced recently for the treatment of SSNHL, but it does not seem to be used widely in Japan. Intratympanic therapy that can reduce the total amount of steroids administered will be used more frequently if the true effects and indications for this therapy are known. Elucidation of the etiologies of SSNHL and development of treatments specific for these etiologies are expected.

Key Words: Sudden deafness, Grading system, Initial hearing level, Final hearing level, Treatment method, Nationwide epidemiological survey

Core tip: Nationwide epidemiological studies of sudden sensorineural hearing loss (SSNHL) were performed five times between 1972 and 2012 in Japan and have revealed that the recovery rate of SSNHL has not improved for 40 years. Elucidation of the etiologies of SSNHL and development of treatments specific for these etiologies are expected.



INTRODUCTION

According to a recent epidemiological study of idiopathic sudden sensorineural hearing loss (SSNHL) in Japan, the outcome of SSNHL has not changed in the past 40 years[1]. Table 1 shows the criteria for grading SSNHL established by the Research Committee of the Ministry of Health and Welfare in Japan in 1988.

Table 1 Criteria for the grading of hearing loss in sudden sensorineural hearing loss.
Grade 1PTA < 40 dB
Grade 240 dB ≤ PTA < 60 dB
Grade 360 dB ≤ PTA < 90 dB
Grade 490 dB ≤ PTA

The grading system is also used to evaluate the final hearing level, which is measured when the hearing level becomes stable[2,3]. Table 2 shows the distribution of the grades of the final audiograms for grade 4 cases at the initial audiogram in five nationwide surveys performed from 1972 through 2012[1-3].

Table 2 Final grades of initial grade 4 cases in five nationwide sudden sensorineural hearing loss surveys in Japan n (%).
19721987199320012012
Grade 126 (14)49 (18)70 (18)25 (15)5 (21)
Grade 231 (16)44 (17)62 (16)36 (22)1 (4)
Grade 387 (46)119 (45)173 (43)68 (41)11 (46)
Grade 445 (24)53 (20)95 (24)38 (23)7 (29)
Total189 (100)265 (100)400 (100)167 (100)24 (100)

The outcome has not differed significantly between the five surveys. Classification of grades 1 and 2 at the final audiogram as the “good recovery group” and grades 3 and grade 4 at the final audiogram as the “poor recovery group” and analysis using the χ2 test showed that the ratio of good to poor recovery has not differed significantly between any survey year. This suggests that the treatment results for the worst grade of SSNHL at the initial examination have not improved in the past 40 years.

TREATMENT METHODS

Table 3 shows the percentages of patients with SSNHL who were treated with steroids, vitamins, stellate ganglion block (SGB), hyperbaric oxygen therapy (HBO), or prostaglandin E1 (PGE1) in 1972, 1987, and 2001 in Japan[3,4].

Table 3 Percentages of patients who received steroids, vitamins, stellate ganglion block, hyperbaric oxygen therapy, or prostaglandin E1 for sudden sensorineural hearing loss.
197219872001
Steroids88%93%85%
Vitamins88%93%92%
SGB24%27%8%
HBO3%12%11%
PGE10%11%33%

The use of PGE1 has increased since the 1980s, but its effect on SSNHL may not be significant[5-7]. Treatment methods for patients who had SSNHL in 2012 have not been investigated. However, steroids remain the main drugs for the treatment of SSNHL at present throughout the world. Intratympanic steroid injection has been introduced recently for the treatment of SSNHL[8], but it does not seem to be used widely in Japan. Intratympanic steroid injection may be used more frequently if the true effects and indications are known as it can reduce the total amount of steroids administered.

EVALUATION OF HEARING RECOVERY

Siegel’s criteria[9] or criteria determined by the Research Committee of the Ministry of Health and Welfare in Japan[10] are used in the evaluation of hearing recovery after SSNHL. These criteria use both the final hearing level and the magnitude of the hearing gain (in dB). The percentage improvement is also used to evaluate the degree of recovery and is calculated by dividing the difference between the initial hearing level and final hearing level by the difference between the initial hearing level and opposite ear hearing level[5]. Another method is used to obtain the percentage of the final hearing grade for each grade of the initial audiogram (Table 2)[1-3]. Various factors are associated with the degree of hearing recovery including the initial hearing loss, shape of the audiogram, interval between the onset of SSNHL and initial visit to an ENT doctor, age, and other factors. It is recommended to use several methods for the evaluation of hearing recovery.

Future problems

To increase the recovery rate of SSNHL, it is essential to investigate the etiology of SSNHL, which is considered a multifactorial disease. 3-Tesla magnetic resonance imaging can be used to evaluate disruption of the blood-labyrinthine barrier by observing the contrast enhancement of the inner ear after intravenous injection of gadolinium contrast agents[11-13]. Increased permeability of the blood vessels is closely associated with inflammation. Whether the effects of steroids with anti-inflammatory function vary according to the condition of the blood-labyrinthine barrier should be settled in future. Development of intratympanic therapy or drug-placement therapy in the round window niche is expected[14-16].

Footnotes

P- Reviewer: Abulezz T, Coskun A S- Editor: Tian YL L- Editor: A E- Editor: Lu YJ

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