Original Paper Audiology Neurotology
Audiol Neurotol 2015;20:195–201 DOI: 10.1159/000377617
Received: September 8, 2014 Accepted: January 29, 2015 Published online: April 25, 2015
Hearing Aid or Tinnitus Masker: Which One Is the Best Treatment for Blast-Induced Tinnitus? The Results of a Long-Term Study on 974 Patients Hamid Jalilvand a Akram Pourbakht b Hamid Haghani c
a Department of Audiology, School of Rehabilitation Sciences, b Department of Audiology, Rehabilitation Research Center, School of Rehabilitation Sciences, and c Department of Statistics, School of Public Health Sciences, Iran University of Medical Sciences, Tehran, Iran
Abstract The aim of this longitudinal study was to explore whether a hearing aid or noise generator would be an effective audiological treatment for blast-induced chronic tinnitus. The amount of satisfaction from different hearing devices (hearing aid, noise generator, or both) during different time periods (1, 6, 12 and 24 months after fitting) was assessed. The 974 subjects enrolled in this study were Iran-Iraq war veterans, suffering from tinnitus for at least 2 years. About 84% of the subjects preferred just a hearing aid. Only 2.7% chose the noise generator, and the others preferred to use both devices. There were no significant differences between the hearing thresholds of the 3 groups. The satisfaction score for the hearing aid and combined devices increased by time but decreased for the noise generator. There was no correlation between the satisfaction score and parameters such as hearing thresholds, audiogram configuration and tinnitus pitch. We concluded that, compared with a noise generator, the most long-lasting treatment for blast-induced tinnitus is a hearing aid. The possible cause for such a performance is probably the recovery of the auditory function and neuroplasticity through the hearing aid. © 2015 S. Karger AG, Basel
© 2015 S. Karger AG, Basel 1420–3030/15/0203–0195$39.50/0 E-Mail [email protected] www.karger.com/aud
Introduction
Soldiers in military and war fields are inevitably exposed to intense noises, which are extremely dangerous for human beings [Altman, 2001]. The blast waves can further result in more dangerous conditions [Wightman and Gladish, 2001]. Regarding auditory organs, such waves cause different impairments and injuries [Kerr, 1987], among which hearing loss and tinnitus are two main impairments [Cave et al., 2007]. Tinnitus is a ringing or buzzing sound that is heard while no external source of sound exists [Eggermont and Roberts, 2004]. There is no exact and direct treatment for tinnitus because it is a symptom [Vio and Holme, 2005]. It is suggested that if there is an auditory input deprivation from the periphery due to pathological insults, the spontaneous activity and neural synchronization of neurons in the upper auditory pathways are increased [Kaltenbach and Afman, 2000; Eggermont and Roberts, 2004; Bauer et al., 2008]. Studies using human brain imaging have also indicated that central auditory systems, such as the inferior colliculus [Giraud et al., 1999] and the auditory cortex [Lockwood et al., 2001] as well as centers of emotional processing such as the limbic system [Eggermont and Komiya, 2000], are involved in tinnitus. Generally, there would be an imbalance between the excitation and inhibition of projection pathways at various levHamid Jalilvand Department of Audiology, School of Rehabilitation Sciences Iran University of Medical Sciences (IUMS), Nezam Street, Shah-nazari Street Madar Square, Mirdamad Avenue, Tehran 1545913187 (Iran) E-Mail hj @ fanaz.ir
Downloaded by: UCONN Storrs 137.99.31.134 - 5/11/2015 3:33:24 PM
Key Words Tinnitus · Hearing aid · Noise generator · Hearing loss · Blast injury
Materials and Methods The subjects enrolled in this study were male soldiers (38–85 years old) who were injured in the Iran-Iraq war (1980–1988). From 2004 to 2011, 974 patients with blast-induced tinnitus and hearing loss (unilateral or bilateral) were carefully visited, and each patient was followed up for 2 years. They were referred to our clinic after their hearing loss and/or tinnitus were diagnosed by audiological tests, ENT visits, medical tests and military documents of their war participation at the time of injury. This study was conducted at the Audiology Department of Veterans Affairs, Kowsar Orthotics and Prosthetics Center, Tehran (Iran). All subjects signed the written informed consent. Otoscopy and immittance test (tympanometry and acoustic reflexes) were carried out successfully. Air and bone conduction audiometry tests were conducted for the frequency range of 250– 8,000 Hz and 250–4,000 Hz, respectively, followed by speech audiometry. If necessary, auditory brainstem response or optoacoustic emission tests were performed to rule out the overlaid retrocochlear pathologies. The audiometry and immittance tests were performed using the instruments OB822 (Madsen Co., Sweden) and AZ7 (Interacoustic Co., Denmark), respectively. The psychoacoustic measurements of tinnitus including pitch matching, loudness matching, minimum masking level and residual inhibition were carried out in accordance with the procedure by Vernon and Meikle [1981] (see online suppl. material C; for all onlinesuppl.material,seewww.karger.com/doi/10.1159/000377617).
196
Audiol Neurotol 2015;20:195–201 DOI: 10.1159/000377617
The guidelines for the treatment were to fit both hearing aid and noise generator in the first stage and to test their effects on the patients’ hearing or tinnitus compensation in the first fitting and during the follow-up sessions (see online suppl. material C). In the first fitting session, the two devices (hearing aid and noise generator) were given to the subjects, and they were asked to try both devices during the first week at home. In addition, a complete description of the hearing aid and noise generator, their mechanism, the goal of the treatment and their maintenance were presented. After 1 week, the proper device was selected. Finally, the patients reported their satisfaction with the instrument and signed the consent form accordingly. When trying every selected device, the change of device was made possible if it was asked for or was necessary. It must be mentioned that during the 2 years of follow-up, the hearing status was checked to control any change in the hearing thresholds. All patients with the hearing aid underwent a real ear measurement, and the hearing aid amplification was matched with NAL-NL1 (National Acoustic Laboratories’ nonlinear fitting procedure version 1) targets in the ranges of ±3 dB. In the fitting session, loudness comfort, retention of hearing aid in the ear, probable occurrence of acoustic feedback and other audiological parameters were assessed. In addition, after matching the measurements with the amplification targets, if there were any loudness discomfort or problems in the sound quality, some modifications were considered according to the patient’s satisfaction. Where necessary, i.e. in cases of hyperacusis or recruitment, the gain and output of the hearing aid were decreased until the acclimatization of the patient to the hearing aid was reached. After the acclimatization, the gain or output of the hearing aid was increased as needed. When fitting the noise generator, the preferable type of noise was selected as the masking noise of tinnitus. The noise level was adjusted according to the tinnitus masking level for every patient. After determining the preferred device and fine tuning, the patients’ satisfaction was scored on a scale of 0–10, indicating not effective to completely satisfactory, respectively, in the 1, 6, 12 and 24 months after fitting the device [Tyler, 2000]. According to the main concept of the study, the loudness reduction, tinnitus elimination, tinnitus relief and the instrument effectiveness during the daily work were investigated when determining the score.
Results
A total of 976 veterans participated in this study. Two subjects were excluded from the study because they exchanged their preferred devices after 6 months. The others (974 subjects) retained the same device until the end of 2 years. All of the enrolled 974 patients were suffering from tinnitus in at least 1 ear. Their hearing thresholds were stable in the range of 10 dB. These veterans with tinnitus, based on the preferred device, were categorized into 3 groups: G1, patients preferred the hearing aid; G2, patients preferred the noise generator, and G3, patients preferred to use both. Jalilvand/Pourbakht/Haghani
Downloaded by: UCONN Storrs 137.99.31.134 - 5/11/2015 3:33:24 PM
els following cochlear damage [Eggermont and Roberts, 2004]. Therefore, if sufficient auditory input is presented into the ear that is affected with tinnitus, the tinnitus may be eliminated or its loudness would at least be decreased [Del Bo and Ambrosetti, 2007; Kleinjung et al., 2009]. Fitting a hearing aid or a noise generator is one of the audiological treatments, particularly if there is some degree of hearing loss. A hearing aid, through the amplification of environmental sounds and speech, compensates the hearing loss, and it also reduces or removes the perception of tinnitus, whereas a noise generator through producing narrow- or wide-band noises and delivering them into the patients’ ears masks the tinnitus, and consequently the patient will not suffer. The main question in the present study was: what is the best treatment for veterans with blast-induced tinnitus? To answer this question properly, we designed a longterm study on a large number of subjects. This study has some advantages for compensating the shortcomings of previous studies, such as its big sample size, the long-term monitoring of treatment effectiveness and the focusing on blast-induced tinnitus. We assessed the degree of patient satisfaction at various time periods of 1, 6, 12 and 24 months after fitting the hearing aid, noise generator, or both.
Noise generator
Hearing aid
Both
Bilateral high pitch tinnitus
10.00 8.00 6.00 4.00 2.00
Bilateral low pitch tinnitus
0 10.00 8.00 6.00 4.00 2.00
Unilateral high pitch tinnitus
0 10.00 8.00 6.00 4.00 2.00
8.00 6.00 4.00 2.00 0 10.00 8.00 6.00 4.00 2.00 0
type of tinnitus pitch in each group during 1, 6, 12 and 24 months after fitting the preferred device, respectively.
1 month
6 months
12 months
24 months
Time after fitting
The average age of the study subjects was 46–47 years, with no statistically significant differences among the 3 groups (p = 0.15; online suppl. table 1). The mean audiograms for each group and the type of tinnitus pitch are shown in online supplementary figures 1 and 2, respectively. There was no significant difference between the hearing thresholds among the 3 groups. There were various audiogram configurations. The patterns of precipitous falling, gradual falling, flat and Z-shaped (zigzag) were highly symmetric in the audiograms of right and left ears. Both ears had a high-frequency pattern in almost 62% of the cases and a non-high-frequency pattern in 16.1% of the cases. There was, however, some strong asymmetry in the audiogram configuration (manuscript in preparation).
It was observed that the high-pitch tinnitus was most common among the high-frequency pattern. When the audiogram pattern changed into another pattern, in which other low frequencies were involved, low-pitch tinnitus became more common (online suppl. fig. 3). The Spearman test showed that there was a correlation between the type of tinnitus pitch and the audiogram configuration (r = 0.43 and r = 0.40 for right and left ears, respectively). This relationship was statistically significant for both ears (p < 0.001). The results of the psychoacoustic measurements of tinnitus are shown in online supplementary table 1. The average satisfaction scores and the standard deviations of satisfaction for the different groups are indicated in online supplementary tables 1 and 2 and in figure 1, based
Hearing Aid or Tinnitus Masker
Audiol Neurotol 2015;20:195–201 DOI: 10.1159/000377617
197
Downloaded by: UCONN Storrs 137.99.31.134 - 5/11/2015 3:33:24 PM
Fig. 1. Mean score of satisfaction for every
Asymmetric pitch tinnitus
Unilateral low pitch tinnitus
0 10.00
Table 1. Statistical characteristics of participants with tinnitus in this study
p value
Characteristics
G1 only hearing aid
G2 only noise generator
G3 both
Numbers (%) Age (mean ± SD)
818 (84) 46.4±7.7
26 (2.7) 46.4±5.9
130 (13.3) 47.8±7.0
0.150
Tinnitus Bilateral high pitch tinnitus (%) Bilateral low pitch tinnitus (%) Unilateral high pitch tinnitus (%) Unilateral low pitch tinnitus (%) Asymmetrical pitch tinnitus (%)
74.9 6.6 1.2 1.1 5.4
57.7 7.7 23.1 3.8 7.7
73.8 7.7 12.3 2.3 3.8
0.504 0.372 0.416 0.126 0.415
9.3±2.3 9.5±2.7
8.8±2.0 10.4±2.1
8.4±1.7 9.7±2.2
0.304 0.241
21.1±4.5 21.4±4.9
18.5±4.1 21.0±4.5
19.2±4.8 19.8±5.1
0.412 0.611
12.3 12.2
3.8 3.8
3.1 3.1
Audiol Neurotol 2015;20:195–201 DOI: 10.1159/000377617
Received: September 8, 2014 Accepted: January 29, 2015 Published online: April 25, 2015
Hearing Aid or Tinnitus Masker: Which One Is the Best Treatment for Blast-Induced Tinnitus? The Results of a Long-Term Study on 974 Patients Hamid Jalilvand a Akram Pourbakht b Hamid Haghani c
a Department of Audiology, School of Rehabilitation Sciences, b Department of Audiology, Rehabilitation Research Center, School of Rehabilitation Sciences, and c Department of Statistics, School of Public Health Sciences, Iran University of Medical Sciences, Tehran, Iran
Abstract The aim of this longitudinal study was to explore whether a hearing aid or noise generator would be an effective audiological treatment for blast-induced chronic tinnitus. The amount of satisfaction from different hearing devices (hearing aid, noise generator, or both) during different time periods (1, 6, 12 and 24 months after fitting) was assessed. The 974 subjects enrolled in this study were Iran-Iraq war veterans, suffering from tinnitus for at least 2 years. About 84% of the subjects preferred just a hearing aid. Only 2.7% chose the noise generator, and the others preferred to use both devices. There were no significant differences between the hearing thresholds of the 3 groups. The satisfaction score for the hearing aid and combined devices increased by time but decreased for the noise generator. There was no correlation between the satisfaction score and parameters such as hearing thresholds, audiogram configuration and tinnitus pitch. We concluded that, compared with a noise generator, the most long-lasting treatment for blast-induced tinnitus is a hearing aid. The possible cause for such a performance is probably the recovery of the auditory function and neuroplasticity through the hearing aid. © 2015 S. Karger AG, Basel
© 2015 S. Karger AG, Basel 1420–3030/15/0203–0195$39.50/0 E-Mail [email protected] www.karger.com/aud
Introduction
Soldiers in military and war fields are inevitably exposed to intense noises, which are extremely dangerous for human beings [Altman, 2001]. The blast waves can further result in more dangerous conditions [Wightman and Gladish, 2001]. Regarding auditory organs, such waves cause different impairments and injuries [Kerr, 1987], among which hearing loss and tinnitus are two main impairments [Cave et al., 2007]. Tinnitus is a ringing or buzzing sound that is heard while no external source of sound exists [Eggermont and Roberts, 2004]. There is no exact and direct treatment for tinnitus because it is a symptom [Vio and Holme, 2005]. It is suggested that if there is an auditory input deprivation from the periphery due to pathological insults, the spontaneous activity and neural synchronization of neurons in the upper auditory pathways are increased [Kaltenbach and Afman, 2000; Eggermont and Roberts, 2004; Bauer et al., 2008]. Studies using human brain imaging have also indicated that central auditory systems, such as the inferior colliculus [Giraud et al., 1999] and the auditory cortex [Lockwood et al., 2001] as well as centers of emotional processing such as the limbic system [Eggermont and Komiya, 2000], are involved in tinnitus. Generally, there would be an imbalance between the excitation and inhibition of projection pathways at various levHamid Jalilvand Department of Audiology, School of Rehabilitation Sciences Iran University of Medical Sciences (IUMS), Nezam Street, Shah-nazari Street Madar Square, Mirdamad Avenue, Tehran 1545913187 (Iran) E-Mail hj @ fanaz.ir
Downloaded by: UCONN Storrs 137.99.31.134 - 5/11/2015 3:33:24 PM
Key Words Tinnitus · Hearing aid · Noise generator · Hearing loss · Blast injury
Materials and Methods The subjects enrolled in this study were male soldiers (38–85 years old) who were injured in the Iran-Iraq war (1980–1988). From 2004 to 2011, 974 patients with blast-induced tinnitus and hearing loss (unilateral or bilateral) were carefully visited, and each patient was followed up for 2 years. They were referred to our clinic after their hearing loss and/or tinnitus were diagnosed by audiological tests, ENT visits, medical tests and military documents of their war participation at the time of injury. This study was conducted at the Audiology Department of Veterans Affairs, Kowsar Orthotics and Prosthetics Center, Tehran (Iran). All subjects signed the written informed consent. Otoscopy and immittance test (tympanometry and acoustic reflexes) were carried out successfully. Air and bone conduction audiometry tests were conducted for the frequency range of 250– 8,000 Hz and 250–4,000 Hz, respectively, followed by speech audiometry. If necessary, auditory brainstem response or optoacoustic emission tests were performed to rule out the overlaid retrocochlear pathologies. The audiometry and immittance tests were performed using the instruments OB822 (Madsen Co., Sweden) and AZ7 (Interacoustic Co., Denmark), respectively. The psychoacoustic measurements of tinnitus including pitch matching, loudness matching, minimum masking level and residual inhibition were carried out in accordance with the procedure by Vernon and Meikle [1981] (see online suppl. material C; for all onlinesuppl.material,seewww.karger.com/doi/10.1159/000377617).
196
Audiol Neurotol 2015;20:195–201 DOI: 10.1159/000377617
The guidelines for the treatment were to fit both hearing aid and noise generator in the first stage and to test their effects on the patients’ hearing or tinnitus compensation in the first fitting and during the follow-up sessions (see online suppl. material C). In the first fitting session, the two devices (hearing aid and noise generator) were given to the subjects, and they were asked to try both devices during the first week at home. In addition, a complete description of the hearing aid and noise generator, their mechanism, the goal of the treatment and their maintenance were presented. After 1 week, the proper device was selected. Finally, the patients reported their satisfaction with the instrument and signed the consent form accordingly. When trying every selected device, the change of device was made possible if it was asked for or was necessary. It must be mentioned that during the 2 years of follow-up, the hearing status was checked to control any change in the hearing thresholds. All patients with the hearing aid underwent a real ear measurement, and the hearing aid amplification was matched with NAL-NL1 (National Acoustic Laboratories’ nonlinear fitting procedure version 1) targets in the ranges of ±3 dB. In the fitting session, loudness comfort, retention of hearing aid in the ear, probable occurrence of acoustic feedback and other audiological parameters were assessed. In addition, after matching the measurements with the amplification targets, if there were any loudness discomfort or problems in the sound quality, some modifications were considered according to the patient’s satisfaction. Where necessary, i.e. in cases of hyperacusis or recruitment, the gain and output of the hearing aid were decreased until the acclimatization of the patient to the hearing aid was reached. After the acclimatization, the gain or output of the hearing aid was increased as needed. When fitting the noise generator, the preferable type of noise was selected as the masking noise of tinnitus. The noise level was adjusted according to the tinnitus masking level for every patient. After determining the preferred device and fine tuning, the patients’ satisfaction was scored on a scale of 0–10, indicating not effective to completely satisfactory, respectively, in the 1, 6, 12 and 24 months after fitting the device [Tyler, 2000]. According to the main concept of the study, the loudness reduction, tinnitus elimination, tinnitus relief and the instrument effectiveness during the daily work were investigated when determining the score.
Results
A total of 976 veterans participated in this study. Two subjects were excluded from the study because they exchanged their preferred devices after 6 months. The others (974 subjects) retained the same device until the end of 2 years. All of the enrolled 974 patients were suffering from tinnitus in at least 1 ear. Their hearing thresholds were stable in the range of 10 dB. These veterans with tinnitus, based on the preferred device, were categorized into 3 groups: G1, patients preferred the hearing aid; G2, patients preferred the noise generator, and G3, patients preferred to use both. Jalilvand/Pourbakht/Haghani
Downloaded by: UCONN Storrs 137.99.31.134 - 5/11/2015 3:33:24 PM
els following cochlear damage [Eggermont and Roberts, 2004]. Therefore, if sufficient auditory input is presented into the ear that is affected with tinnitus, the tinnitus may be eliminated or its loudness would at least be decreased [Del Bo and Ambrosetti, 2007; Kleinjung et al., 2009]. Fitting a hearing aid or a noise generator is one of the audiological treatments, particularly if there is some degree of hearing loss. A hearing aid, through the amplification of environmental sounds and speech, compensates the hearing loss, and it also reduces or removes the perception of tinnitus, whereas a noise generator through producing narrow- or wide-band noises and delivering them into the patients’ ears masks the tinnitus, and consequently the patient will not suffer. The main question in the present study was: what is the best treatment for veterans with blast-induced tinnitus? To answer this question properly, we designed a longterm study on a large number of subjects. This study has some advantages for compensating the shortcomings of previous studies, such as its big sample size, the long-term monitoring of treatment effectiveness and the focusing on blast-induced tinnitus. We assessed the degree of patient satisfaction at various time periods of 1, 6, 12 and 24 months after fitting the hearing aid, noise generator, or both.
Noise generator
Hearing aid
Both
Bilateral high pitch tinnitus
10.00 8.00 6.00 4.00 2.00
Bilateral low pitch tinnitus
0 10.00 8.00 6.00 4.00 2.00
Unilateral high pitch tinnitus
0 10.00 8.00 6.00 4.00 2.00
8.00 6.00 4.00 2.00 0 10.00 8.00 6.00 4.00 2.00 0
type of tinnitus pitch in each group during 1, 6, 12 and 24 months after fitting the preferred device, respectively.
1 month
6 months
12 months
24 months
Time after fitting
The average age of the study subjects was 46–47 years, with no statistically significant differences among the 3 groups (p = 0.15; online suppl. table 1). The mean audiograms for each group and the type of tinnitus pitch are shown in online supplementary figures 1 and 2, respectively. There was no significant difference between the hearing thresholds among the 3 groups. There were various audiogram configurations. The patterns of precipitous falling, gradual falling, flat and Z-shaped (zigzag) were highly symmetric in the audiograms of right and left ears. Both ears had a high-frequency pattern in almost 62% of the cases and a non-high-frequency pattern in 16.1% of the cases. There was, however, some strong asymmetry in the audiogram configuration (manuscript in preparation).
It was observed that the high-pitch tinnitus was most common among the high-frequency pattern. When the audiogram pattern changed into another pattern, in which other low frequencies were involved, low-pitch tinnitus became more common (online suppl. fig. 3). The Spearman test showed that there was a correlation between the type of tinnitus pitch and the audiogram configuration (r = 0.43 and r = 0.40 for right and left ears, respectively). This relationship was statistically significant for both ears (p < 0.001). The results of the psychoacoustic measurements of tinnitus are shown in online supplementary table 1. The average satisfaction scores and the standard deviations of satisfaction for the different groups are indicated in online supplementary tables 1 and 2 and in figure 1, based
Hearing Aid or Tinnitus Masker
Audiol Neurotol 2015;20:195–201 DOI: 10.1159/000377617
197
Downloaded by: UCONN Storrs 137.99.31.134 - 5/11/2015 3:33:24 PM
Fig. 1. Mean score of satisfaction for every
Asymmetric pitch tinnitus
Unilateral low pitch tinnitus
0 10.00
Table 1. Statistical characteristics of participants with tinnitus in this study
p value
Characteristics
G1 only hearing aid
G2 only noise generator
G3 both
Numbers (%) Age (mean ± SD)
818 (84) 46.4±7.7
26 (2.7) 46.4±5.9
130 (13.3) 47.8±7.0
0.150
Tinnitus Bilateral high pitch tinnitus (%) Bilateral low pitch tinnitus (%) Unilateral high pitch tinnitus (%) Unilateral low pitch tinnitus (%) Asymmetrical pitch tinnitus (%)
74.9 6.6 1.2 1.1 5.4
57.7 7.7 23.1 3.8 7.7
73.8 7.7 12.3 2.3 3.8
0.504 0.372 0.416 0.126 0.415
9.3±2.3 9.5±2.7
8.8±2.0 10.4±2.1
8.4±1.7 9.7±2.2
0.304 0.241
21.1±4.5 21.4±4.9
18.5±4.1 21.0±4.5
19.2±4.8 19.8±5.1
0.412 0.611
12.3 12.2
3.8 3.8
3.1 3.1
