AUDIOLOGIC PROFILE OF OLDER ADULTS SUBJECTED TO VESTIBULAR REHABILITATION THERAPY Perfil audiológico de idosos submetidos à reabilitação vestibular

Conflict of interest: non-existent Aging is directly associated with the presence of otoneurological symptoms4. As the auditory system exhibits anatomical-physiological continuity with the labyrinth, aging is associated with physiological changes in both the cochlea, which is responsible for hearing, and the vestibular system, which is responsible for balance5. Both are located in the temporal bone, specifically in the labyrinth4,6, and communicate through the ductus reuniens, which connects the saccule to the cochlear duct4. The organ of Corti is part of the membranous labyrinth, being contained in the same compartment as the utricular macula, saccular macula, and crista ampullaris. Therefore, otological complaints related to the inner ear are common among older adults. The body balance is maintained by the vestibular, visual, and proprioceptive systems, and when those skills are affected, the response of those systems decreases, resulting in vertigo or dizziness7,8. The risk factors associated with dizziness include cardiovascular, cerebrovascular, neurological, sensory, and metabolic diseases9. The prevalence of presbycusis, i.e., age-related auditory loss, is high among older adults; this  INTRODUCTION


INTRODUCTION
Older adults, according to the World Health Organization (WHO), are individuals older than 65 years old; however, in Brazil, old age is considered to begin at 60 1,2 .Aging is associated with progressive and dynamic physiological changes, resulting in increased vulnerability and higher incidence of pathologies 1,3 .According to the WHO, by 2025, Brazil will rank sixth in the number of older adults worldwide, with an estimated elderly population of 32 million people 2,3 .The ongoing increase in life expectancy requires establishing care and adjustment to meet the needs of the elderly 3 .
a public hospital from August to December 2013 who met the inclusion criteria and voluntarily agreed to participate in the study.The older adults with dizziness were referred from otorhinolaryngologists at primary care facilities to perform vestibular rehabilitation therapy, while the ones without dizziness were referred by geriatrists for auditory testing.
Individuals aged 60 years old or older from both genders were considered eligible to participate in the study.Individuals with physical, cognitive, or sensory limitations that could hinder the performance of the auditory tests and individuals unable to understand and respond to simple verbal commands were excluded from the study.
The participants were informed as to the voluntary nature of participation, as well as on the study procedures, stressing that they would not pose any health risk.The participants responded to a questionnaire that collected data on hearing complaints, family history of hearing loss, history of acoustic trauma, tinnitus, and balance-related complaints.Based on the questionnaire data, the participants were allocated into two groups: Group 1 -individuals with dizziness; and Group 2individuals without dizziness.
The participants were then subjected to inspection of the external auditory meatus to establish whether its condition was adequate for auditory assessment.Next, pure-tone threshold audiometry was performed in a sound-isolated room using an audiometer Interacoustics® model AVS-500.The air conduction audibility thresholds were measured using TDH-39 earphones at the frequencies 250, 500, 1,000, 2,000, 3,000, 4,000, 6,000 and 8,000 Hz.The bone-conduction thresholds were measured using vibrator B71 at the frequencies 500, 1,000, 2,000, 3,000 and 4,000 Hz bilaterally.Speech audiometry was performed by a single examiner using a loudspeaker, the intensity of which was controlled by the audiometer speech level indicator.The parameters assessed were the Speech Discrimination Score of 100% (SDS) and Speech Reception Threshold (SRT) of both ears.The results of pure-tone audiometry were analyzed according to the BIAP (1997) classification, which is based on the average air conduction audibility threshold at 500, 1,000, 2,000 and 4,000 Hz and considers values up to 20 dBal as normal 21 .The classification of the hearing loss type (sensorineural, conductive, or mixed) and audiometric configuration followed the criteria formulated by Silman and Silverman (1997) 21 .The results of speech audiometry were classified according to Jerger, Speaks & Trammell (1968) 22 .
condition impairs the ability to understand speech 4,10 .From the audiological perspective, it is characterized by sensorineural hearing loss, with the auditory threshold for high frequencies affected.As a function of age, the mitotic capacity of some cells decreases, intracellular pigments accumulate, and the intercellular fluid undergoes changes 11 .Thus, the entire auditory organ (outer, middle, and inner ear, central auditory pathways) is affected by aging 12,13 .As a rule, the hearing loss is due to degeneration of the cochlea, affecting the basal portion of this organ, where the high-frequency sounds are identified.Therefore, the appearance of those structural changes throughout the system is expected to cause hearing decline with age 6,13,14 .Presbycusis is considered to be the main cause of hearing deficiency among older adults, with a prevalence of 30% among individuals older than 65 years old 15,16 .
Among older adults, hearing loss can be associated with difficulties in oral communication and in understanding the spoken language, especially in noisy environments, with relevant consequences for the elderly within their social and familial environment.Among sensory deficits, hearing loss is the one that exerts the greatest impact on the life of individuals because it reduces the ability to share ideas and thoughts through the oral language [16][17][18] .The main difficulties exhibited by older adults with hearing loss concern the ability to talk on the phone, understand some words, hear alarms and doorbells, locate the source of sounds, and talk with a large audience 19,20 .
As a function of the aforementioned facts, the degree of hearing loss might be greater in older adults with dizziness compared to older adults without this complaint: the affection of the vestibular system might imply concomitant cochlear disorders, as both systems are anatomically located within the same organ.
The aim of this study was to characterize the auditory profile of older adults with dizziness subjected to vestibular rehabilitation therapy and to compare the results with the profiles of older adults without dizziness.

This
cross-sectional, observational and analytical study was approved by the research ethics committee of Federal University of Minas Gerais, ruling no.0551/11.All the participants were informed as to the study procedures and voluntarily signed an informed consent form.
The study's non-probabilistic sample comprised 87 individuals cared for at two outpatient clinics of sample was non-probabilistic, and more individuals without dizziness were referred for auditory testing than individuals with dizziness.Nevertheless, the average age was similar in both groups, 75.7 years old in Group 1 and 76.9 years old in Group 2; that difference was not statistically significant (p=0.661).The number of women with dizziness was larger; however, the difference in the number of women between the groups was not significant (p=1).Audiometry detected a predominance of bilateral hearing loss, as shown in Table 1.
The data collected in the interviews indicated that tinnitus was the most frequent complaint in either group.No statistically significant difference was detected regarding history of acoustic trauma, tinnitus, or family history of hearing loss between the groups (Table 2).
The database was discussed by the investigators and built using the software Excel.Statistical analysis was performed using the software SPSS (Statistical Package for the Social Sciences) version 17.0.The data were first subjected to descriptive analysis, including measures of proportion, central tendency, and dispersion, and then, the chi-square test was used to assess the categorical variables and the non-parametric Mann-Whitney test was used to assess the continuous variables.The significance level was set to 5% in all analyses.

RESULTS
The sample comprised 87 older adults, 35 of whom complained of dizziness (Group), while 52 did not (Group 2).That difference was because the  Audiometry revealed a predominance of sensorineural hearing loss, 79.3%, followed by normal hearing, 14.4%, and mixed hearing loss, 6.3%.Mild sensorineural hearing loss prevailed in the study sample.The audiometry findings corresponding to both groups are described in Table 4.
Analysis of the audibility thresholds found a predominance of sensorineural hearing loss.A loss of 5-10 dB per octave was detected in the average air conduction auditory thresholds toward the high frequencies, thus defining a mild downward sloping configuration (Table 3).consequent impact on the mental domain, inducing irritation, anxiety, depression, and insomnia 27 .Some studies have found bilateral tinnitus in more than 50% of individuals with presbycusis 26,28 .In this study, tinnitus was the symptom most frequently reported by the participants in both groups, with prevalences similar to the values reported by the abovementioned studies.
From the audiological perspective, presbycusis is characterized by sensorineural hearing loss, with poorer auditory thresholds in the high frequencies 1,16 .It is considered to be the sensory deficiency most commonly associated with aging, with a prevalence of up to 35% among individuals aged 60 to 70 years old 26 .In this study, more than 70% of the sample exhibited mild-to-moderate hearing loss (Table 4), with a mild downward sloping configuration in both groups (Table 3).These findings corroborate the results of other studies that investigated hearing in older adults 10,23,24,29 .As presbycusis is associated with aging, being caused by auditory degeneration of the basal portion of the cochlea 12,24 , the predominance of sensorineural hearing loss attended by gradual affection of the audibility thresholds was expected, as the high frequencies are the most severely affected in presbycusis.
That fact might be explained on physiological grounds, as the loss of hair cells occurs in the basal portion of the cochlea, where high-frequency sounds stimulate the local nerve fibers 12,13,16 .
Understanding speech is an essential requirement for efficacious communication; for that reason, the performance of speech audiometry is

DISCUSSION
The sample of this study comprised 87 participants, and women predominated in both groups (with or without dizziness).According to the Brazilian Institute of Geography and Statistics, the number of women in the Brazilian population is larger than the number of men, as the life expectancy of the former is longer compared to the latter 23 .Those facts account for the larger percentage of women among older adults 1,9 .In this study, dizziness predominated among the women, which corroborates reports in the literature indicating that the frequency of dizziness is significantly higher among women 1,13,20 .
Presbycusis is a form of sensorineural hearing loss, and it is considered to be the main cause of hearing deficiency among older adults, its prevalence varying from 30 to 66.4% among individuals older than 65 years old 15,16 .In this study, bilateral hearing loss predominated in both groups, with a much higher proportion than has been reported in other studies 15,16 .Moreover, other factors might also affect hearing in older adults 11,24 , which makes it difficult to establish whether the high proportion of bilateral hearing loss found in this study might be exclusively attributed to aging of the inner ear.
The prevalence of hearing loss and tinnitus increases with age 25 .Tinnitus is one of the main symptoms associated with hearing loss and is sometimes more disturbing than deafness itself 26 .According to some studies, tinnitus might interfere with leisure activities, rest, sleep, social life, activities of daily living, and professional activities, with In speech audiometry, the SDS values found indicated difficulty with speech at a normal conversational level 21 .That finding is compatible with the predominance of participants with mild to moderate I sensorineural hearing loss.The results of speech audiometry corresponding to both groups are described in Table 5.
of participants with dizziness exhibited profound sensorineural hearing loss (Table 4), no difference was found in the auditory profile between the groups.
Among the limitations of this study, the difference in the size of the groups stands out.As this study was merely observational, further studies with larger numbers of participants with severe and profound sensorineural hearing loss are needed to elucidate the possible association.

CONCLUSION
Although the vestibular and auditory systems are anatomically located in the same organ, characteristics indicative of differences in the auditory profile between individuals with or without dizziness were not found.The highest proportion of cases corresponded to mild bilateral sensorineural hearing loss, attended by mild downward sloping toward the high frequencies.
indispensable in the assessment of hearing 30 .In this study, the average SDS for monosyllabic words was approximately 70% in both ears, which indicates moderate difficulty in understanding speech 22 .Sensorineural hearing loss is characterized by reduced speech discrimination, resulting in difficulties in understanding the spoken language and in oral communication, especially in noisy environments, with consequent reduction of the social and family activities of older adults 16,17,19 .Hearing loss is a serious limitation for the elderly, eventually resulting in social isolation as a function of the difficulty in communicating with their environment 28 .

Table 1 -Descriptive data relative to the age, gender, and audiometry results of the sample
Caption: N: absolute number; HL: hearing loss; SD: standard deviation; %: percentage

Table 2 -Data on the presence of trauma, tinnitus, and family history in both groups
*p significance value (chi-square test)

Table 3 -Data on air conduction thresholds of audibility in groups with or without dizziness
*p significance value (Mann-Whitney test)Caption: SD: standard deviation