Correlation Between Sensorineural Hearing Loss and Chronic Otorrhea
Many studies have been trying to correlate chronic otorrhea, both in children and in adults, with the sensorineural hearing loss in the affected ear, but have been obtaining contradictory results. This loss might be due to the likely toxicity of the bacteria involved, effects of inflammatory cytokines, or constant use of ototoxic antibiotics. All the studies evaluated up to the present date compared the affected ear with the normal contralateral ear. From the digitized archive of otological surgery files of the Department of Otorhinolaryngology, the ears of patients with chronic otorrhea were evaluated visually and compared with the normal contralateral ears. Ears with otorrhea were also compared to ears with dry tympanic perforation of other patients. Ears with suppuration were evaluated for cholesteatoma. The duration of otorrhea was taken into account. The sensorineural hearing threshold was evaluated for the frequencies of 500, 1000, 2000, and 4000 Hz. A total of 98 patients with chronic otorrhea and 60 with dry tympanic membrane perforation were evaluated. From a statistical study, a correlation between sensorineural hearing loss and the chronic otorrhea was observed, in comparison both with contralateral normal ears and with dry perforated ears of other patients. There was no relationship with the duration of suppuration or with whether this was due to cholesteatoma. Sensorineural hearing loss occurs in ears with chronic otorrhea. The duration of otorrhea and the etiology of suppuration did not influence the hearing loss. The great majority of otorrhea cases begin during childhood.
Keywords sensorineural, hearing loss, otorrhea, pediatric
Studies dealing with the correlation between chronic otorrhea and ipsilateral sensorineural hearing loss (SNHL) among large numbers of patients have mostly been produced in countries with populations with low purchasing power where chronic otitis media is endemic, as seen in Brazil. The data are conflicting, and there is still no proof regarding this subject, perhaps because of inadequate methodologies.1-3 Many patients have otorrhea during the following years, due to diseases that begin insidiously during childhood, such as secreting otitis media or undiagnosed or poorly treated dysfunctions of the auditory tube that evolve to conditions of chronic suppurative otitis media. The causes of SNHL are thought to relate to the toxicity of the infectious condition, the associated inflammatory cytokines, or the local ototoxic drugs that are usually used. Through the permeability of the oval and round windows, these would compromise the ciliated cells of the organ of Corti of the cochlea.4,5 Among the studies surveyed, only one was conducted in Brazil.6 All the studies correlated the sensorineural hearing thresholds of the compromised ear with those of the contralateral ear without otorrhea. Many took into consideration the time involved5-8 and some the causative disease and whether cholesteatoma was involved.1,4,6 If an SNHL really occurs and is related to the duration of the otorrhea, diagnosing and treating it at an early stage might avoid the need for these patients to use hearing aids to complement their hearing even after the surgical cure of the disease.9,10
The objective of this article is to evaluate whether there is any correlation between the duration of SNHL in chronic otorrhea cases and whether the duration of the disease or its etiology interferes in this hearing loss.
This was a cross-sectional study. It was approved by the research ethics committee under the number 634.869 on April 30, 2014.
A total of 98 ears with chronic otorrhea and 60 ears with dry tympanic perforation were evaluated. Data on the ears of patients with unilateral chronic otorrhea (chronic suppurative otitis media for many years) obtained from the digitized files of the Department of Otorhinolaryngology of an academic institution in the municipality of São Paulo were selected, and the hearing thresholds were evaluated using the frequencies of 500 Hz, 1 kHz, 2 kHz, and 4 kHz in presurgical audiometry. Only the sensorineural thresholds were considered: conductive losses relating to lesions in the middle ear caused by the disease were not taken into account. These thresholds were subtracted from the respective thresholds of the contralateral normal ears (taking the patient’s otoscopy results and history into account), with the aim of eliminating any other type of bilateral compromise, such as presbycusis. The same procedure was performed among patients who had had dry perforations of the tympanic membrane for many years. In the case of chronic otorrhea that for any reason had ceased for a period of time, as reported by the patient, the lengths of time for which otorrhea was active were added together. The patients’ ages were also evaluated, and the etiology of the otorrhea was considered, that is, whether the suppuration was caused by cholesteatoma.
Inclusion Criteria
- Patients with unilateral suppurative otitis media for over a year and a contralateral normal ear, and patients with dry tympanic perforation. The evaluation was performed using digitized otoscopy and the patient’s history.
Exclusion Criterion
- Any other type of otological compromise, such as:
- ○ Previous surgery;
- ○ Otological or cephalic trauma;
- ○ Exposure to noise.
The statistical analysis was performed by means of the SPSS software, version 13. We used Student t test for paired samples to analyze occurrences of otorrhea in patients with one ear presenting suppuration and a normal contralateral ear. We used Student t test for independent samples to analyze neurosensory loss among patients with otorrhea and among patients with dry perforation of the tympanic membrane. Because of nonparametric data, with the presence of outliers that distorted the mean values of the sample, we applied the Kruskal-Wallis and Mann-Whitney U test to compare suppurated ears with and without cholesteatoma. Lastly, we used Pearson correlation to analyze the length of time with otorrhea and neurosensory loss.
A total of 98 patients presenting one ear with otorrhea and a contralateral normal ear, and 60 patients in a control group with dry tympanic perforation, were evaluated. Thus, 158 patients were evaluated. Among the patients who sought our services with otorrhea, 39 were within the pediatric age-group (less than 18 years old), and 20 reported that their symptoms had started during childhood but had only sought medical care in adulthood. Therefore, 60.2% of the chronic otorrhea media cases had begun during childhood. The average age was 32.2 years, and the median value of 26.5 years old was used. The average duration of the otorrhea was 11.6 years and the median value was 6.0.
Figure 1 shows a comparison, in the same patient, between a dry ear and an ear with otorrhea. Using Student t test, it was concluded that there was a difference in SNHL between the normal and affected ears at all frequencies, with statistical significance (P < .001).
Figure 1. Hearing loss in decibels (y-axis) versus frequencies in normal ears (N) and ears with chronic otorrhea (D; x-axis).
A comparison between the ears of patients with dry tympanic perforations and the ears of patients with chronic otorrhea can be seen in Figure 2. Through using Student t test, it was concluded that there was a difference in SNHL between ears with dry perforation and ears with chronic otorrhea at all frequencies, with statistical significance (P < .001).
Figure 2. Hearing loss in decibels (y-axis) versus frequencies of ears with perforation without otorrhea and with chronic otorrhea (x-axis).
Figure 3 shows a comparison between suppurated ears without cholesteatoma and suppurated ears with cholesteatoma. Through the Mann-Whitney U test, it was shown that there was no difference in SNHL among patients with chronic otorrhea and between those with and without cholesteatoma.
Figure 3. Hearing loss in decibels (y-axis) versus frequencies in ears with suppurative chronic otitis media (COM) with and without cholesteatoma (x-axis).
The correlations at each frequency between the duration of the otorrhea and the sensorineural loss, shown through the Pearson correlation, can be seen in Figure 4A-D.
Figures 4. A-D, Hearing loss in decibels at each frequency (y-axis) versus duration of otorrhea (x-axis). PC indicates Pearson correlation.
In other studies found in the worldwide literature, the relationship between chronic otorrhea and SNHL is presented a few times in a controversial, not well-defined manner. Whether the duration of the otorrhea interferes with hearing loss and its etiology, and whether the etiology derives from cholesteatoma and aggravates the sensorineural loss, is not well discussed.1-3 In the present study, a large number of patients (98) was evaluated, firstly comparing the ear with chronic otorrhea with the normal contralateral ear, as the majority of previous authors did,4,5,7,8 and then, in addition, examining the correlation between the suppurated ears of these patients with 60 ears of patients with dry membrane perforation. The duration of the otorrhea was also taken into consideration, along with whether it was continuous. If it was not continuous, we summed the lengths of time for which this symptom was present (suppurative chronic otitis media). In order to remove possible bilateral sensorineural losses among older patients with presbycusis, the values of the respective contralateral ears were subtracted from the values at each frequency in the affected ears, thus defining the real loss value.
In Figure 1, a threshold of approximately 15 dB can be seen in the normal ears, compared with a hearing loss of 40 dB in the suppurated ears. It is important to highlight that at the frequencies evaluated, there was no progressive loss for the higher pitches, which would have been expected if this loss had been due to continuity of the infected middle ear, through the oval and round windows, with the base of the cochlea, where these sounds are processed.
Figure 2 shows a comparison between the suppurated ears and the dry perforated ears of other patients. The average threshold of the dry ears was practically 0 dB, compared with 40 dB in the suppurated ears. Thus, ears with dry perforations with sporadic otorrhea did not interfere with the sensorineural thresholds.
In Figure 3, no correlation was observed between the etiology of the suppuration, that is, whether caused by cholesteatoma, and the SNHLs.6 Thus, the loss was evidently caused by the suppuration itself, without any interference from any other factor present in the cholesteatoma.
Figures 4A-D show that the duration of the otorrhea did not influence the increase in SNHLs. These losses occur during the first years of the disease and last throughout the patients’ lives. This finding was unexpected, because the duration of the disease should interfere with the hearing loss. Perhaps this did not occur because the duration of the chronic inflammatory process somehow protects the oval and round windows from possible contamination of the inner ear. It needs to be remembered that, in parallel with the duration of the otorrhea, treatment with ear drops is being administered, generally containing ototoxic antibiotics. Thus, it was possible to confirm that chronic otorrhea gives rise to SNHL, but not that the cause was the infectious process itself rather than indiscriminate use of ear drops for long periods of time. These diseases begin insidiously during childhood due to tube problems consequent to rhinitis, sinusitis, or hypertrophy of the tonsils and adenoids, thereby leading to secretory otitis, aspirations, and tympanic perforations. Early treatment of the disease or its causes may avoid not only the inherent conductive loss, for which surgical treatment is sometimes only partial, but also the irreversible SNHL deficiency. Thus, otorrhea of the middle ear gives rise to neurosensory auditory deficiency that is processed equally at all frequencies, but does not worsen with increasing length of evolution of the disease. In our sample, we did not find any evidence to show that cholesteatoma influences hearing loss, and the dry perforation does not cause neurosensory loss. Most of the patients with chronic infection start to show symptoms during childhood.9
Authors’ Note
The research does not involve patients or animals. Approved by the research ethics committee number 634.869 on April 30, 2014.
The research does not involve patients or animals. Approved by the research ethics committee number 634.869 on April 30, 2014.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
The author(s) received no financial support for the research, authorship, and/or publication of this article.
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