This study conducted among the patients attending in RIMS, Kadapa to ascertain the risk factors for causing complications of HS in adults. Out of 288 patients male ratio was slightly increased when compared to women, similarly in a cohort study showed 57% male ratio. Most people fall in the age group of 60–80 years.
Conflict of interest statement
The authors are grateful to staffs of Rajiv Gandhi Institute of Medical Sciences for their contribution and help.
Otoacoustic emissions are tests used to determine the hair cell function of the cochlea. So otoacoustic emission testing can be used as a tool to determine the presence or absence of cochlear function and analysis can be performed for individual cochlear frequency regions. Another potential use of distortion product otoacoustic emissions (DPOAE) measurements might be to predict auditory response growth, such as growth of loudness. This application would be of interest clinically because one consequence of cochlear hearing loss may be an abnormal growth of loudness, sometimes referred to as loudness recruitment.
DPOAEs are sounds emitted in response to 2 simultaneous tones of different frequencies. Stimuli consist of 2 pure tones at 2 frequencies (f2 > f1) and two intensity levels (L1, L2). The relationship between L1–L2 and f1/f2 dictates the frequency response. DPOAEs allow great frequency specificity with a great reliability above 1000 Hz.
Hearing losses above 50 dB HL are not quantifiable using DPOAEs and their performance at frequencies below 1 kHz is limited, but their recording time is short.
Presence of hearing loss and estimation of type and degree is one of the most common methods used to investigate the effects of renal disease on the auditory system. Degree of hearing loss may give an indication of the extent of damage to auditory function, whereas the type of hearing loss may distinguish between lesions in the outer and middle ear (conductive hearing loss) or the cochlea and the neural pathways (sensorineural hearing loss). According to these ionophore indicators , the reports to be reviewed in the following sections have also described auditory function in CRF with methods such as tympanometry, audiometry and otoacoustic emissions (distortion product OAEs, DPOAEs).
Materials and methods
The criteria for case selection were: age 15–50 years, hearing impairment after the occurrence of renal failure, no history of noise exposure, no history of diabetes, no history of renal transplantation.
According to the results of the examinations done to the patients oocyte showed that 29 patients out of 43 under hemodialysis treatment had sensorineural hearing loss in high frequencies in audiometric measurements and 33 of them had decreased DPOAE amplitudes (Figure 1).
In the control group only one patient had pure tone audiometry (PTA) threshold low in high frequencies and DPOAE gram according to the audiogram but lower values in >4000 Hz.
It was observed a higher incidence of hearing loss in stages three, four and five of renal failure with lower amplitudes in the DP-gram than PTA thresholds in the same frequencies (Figures 2 and 3).
The survival of chronic renal failure patients is increased with the new hemodialysis treatments.
As screening tools, DPOAEs are superior to PTA testing. DPOAE amplitude reduces significantly before behavioral threshold changes are noted at corresponding frequencies in PTA. Decreased emissions in the presence of normal behavioral hearing may indicate an underlying pathologic condition, which if continued might soon result in a significant hearing loss. In this sense, the DP-grams may be predictive, foretelling a substantial threshold shift for a given frequency before a measurable sensitivity loss.
DPOAEs have an extensive dynamic range regarding hearing loss and can be measured over a broader frequency range with more sensitive frequency specific response. With their high sensitivity and excellent reliability, their objectivity makes them ideal for testing patients who cannot cooperate in a traditional examination of behavioral hearing. Their recording is easy for both technician and patient, and can be easily performed at the bedside. DPOAE audiograms provide a tool for a fast automated frequency-specific and quantitative evaluation of a mild or moderate hearing in follow-up diagnosis.