International Journal of Pediatric Otorhinolaryngology Extra
Volume 1, Issue 3 , Pages 192-195, September 2006

Hearing changes in the contralateral ear with juvenile unilateral profound hearing loss of unknown origin

Department of Otolaryngology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan

Received 14 February 2006; received in revised form 18 April 2006; accepted 25 April 2006.

Article Outline

Summary 

Objectives: Investigate contralateral hearing changes in patients with juvenile unilateral profound hearing loss (JUPHL) of unknown origin because patients with JUPHL have potentially bilateral hearing loss. Study design: A retrospective study. Setting: A tertiary referral center. Patients: Fifty patients with JUPHL of unknown origin included 42 unilaterally deaf patients and 8 patients with hearing loss over 70dB HL. The age of the patients was less than 15 years old at the first visit to our outpatient clinic. Patients with inner ear anomalies were excluded using CT images. Main outcome measures: The results of pure tone audiometry (PTA) were investigated. To obtain reliable PTA results, patients were over 6 years old. The following items were examined: level, fluctuation and worsening of hearing. Results: A hearing level over 30dB was observed at 20%, 4%, and 10% of patients in the low, middle and high frequencies, respectively. Hearing fluctuations were observed in 72%, 42% and 64% at the low, middle and high frequencies, respectively. Hearing worsening was observed in 8%, 4% and 4% at the low, middle and high frequencies, respectively. Conclusion: Seventy-two percent of patients with JUPHL had fluctuating hearing at low frequencies, and 8% of them had worsening hearing. These results imply that over 70% of patients with JUPHL may develop contralateral hearing loss and that we have to follow-up patients with unilateral juvenile profound hearing loss for a long time.

Keywords: Juvenile unilateral profound hearing loss, Pure tone audiometry, Unknown origin

 

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1. Introduction 

Unilateral hearing impairment is generally regarded as a minor inconvenience. Some investigators have reported that there are no or few differences between normal hearing groups and unilateral hearing impairment groups [1], [2]. However, others have reported that some children with early onset unilateral hearing impairment do experience problems in terms of auditory and linguistic abilities and have educational and/or behavioral complications [3], [4], [5]. Recently, Lieu [6] reviewed Speech-language and educational consequences of unilateral hearing loss in children. He concluded that school age children with unilateral hearing loss appear to have increased rates of grade failures, need for additional educational assistance, and perceived behavioral issues in the classroom. Speech and language delays may occur in some children with unilateral hearing loss, but it is unclear if children “catch up” as they grow older. Research into this area is necessary to clarify these issues and to determine whether interventions may prevent potential problems. Even though these issues are still controversial, the contralateral hearing in patients with juvenile unilateral profound hearing loss (JUPHL) is critical.

No matter what its cause, a prolonged case of profound hearing loss can induce delayed endolymphatic hydrops (DEH) [7]. The most common cause of the profound hearing loss that precedes DEH is JUPHL [8], [9], [10], [11]. Patients with JUPHL develop bilateral hearing loss if contralateral DEH is induced. Therefore, to follow-up the hearing in patients with JUPHL for a long time is very important. In this study, we investigated contralateral hearing in patients with JUPHL and discussed its properties.

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2. Materials and methods 

Fifty patients with juvenile unilateral profound hearing loss (JUPHL) of unknown origin were studied. Forty-two were unilaterally deaf and eight had hearing loss sworse than 70dB HL. The age of the patients was less than 15 years old when they visited our outpatient clinic the first time. Table 1 shows a summary of the patients. The average of age was 7.6±2.9 years old at the first visit. There was no difference in terms of sex or side. The period of follow-up was 8.8±3.9 years old. Patients with inner ear anomalies were excluded using computed tomography.

Table 1. Summary of the patients with unilateral juvenile profound hearing loss
Age at first visit (year)7.6±2.9
Male:female22:28
Right:left23:27
Period of follow-up (year)8.8±3.9

Results of pure tone audiometry were investigated for hearing levels, fluctuations, and worsening at all frequencies. Further, hearing level, fluctuation and worsening were examined at low, middle and high frequencies. Hearing level at low frequency averaged the thresholds at 125, 250 and 500Hz, that at the middle frequency averaged the thresholds at 500, 1000 and 2000Hz, while that at the high frequency averaged the thresholds at 2000, 4000 and 8000Hz. Hearing loss indicates that the highest hearing level was over 30dB HL during the follow-up period. Fluctuation of hearing means that hearing levels changed by more than 10dB during the follow-up period. Worsening of hearing means that the hearing level worsened by more than 10dB between the first and last visits. To obtain reliable PTA results, patients were over 6 years old.

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3. Results 

Fig. 1 shows the average results of PTA at first visit and the average of the highest threshold at all frequencies during the follow-up period. The audiologic patterns reached a peak of sensitivity at 1000Hz. Table 2 shows the average hearing levels at the first visit for low, middle and high frequencies. The hearing level was statistically significantly higher at low frequencies than at middle or high frequencies (p<0.001). Table 3 shows the average of the highest threshold during the follow-up period at low, middle and high frequencies. The average at the low frequencies was statistically higher than at other frequencies. The proportion of patients with hearing loss over 30dB HL at low frequency is higher than at other frequencies. Fig. 2 shows the average of the threshold fluctuation range at all frequencies during the follow-up period. Table 4 shows the average threshold fluctuation range during the follow-up period at low, middle and high frequencies. There was no statistical difference among the three frequencies. However, there were more hearing fluctuations at low and high frequencies than at middle frequencies. Fig. 3 shows the threshold worsening between the first and last visits. Table 5 shows the average threshold worsening between the first and last visit at low, middle and high frequencies. There was no statistical difference among the three frequencies.

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  • Fig. 1. 

    The mean value of pure tone thresholds at the first visit and the highest threshold during the follow-up period. Closed and open circles indicate the mean pure-tone thresholds and the average of the highest threshold, respectively. Error bars indicate the standard deviation of the means.

Table 2. Average hearing level at the first visit

There were significant differences between hearing level at low frequencies and at other frequencies. The hearing level at low frequencies was averaged from thresholds at 125, 250 and 500Hz. The hearing level at middle frequencies was averaged from thresholds at 500, 1000 and 2000Hz. The hearing level at high frequency was averaged from thresholds at 2000, 4000 and 8000Hz. The t-test was used to evaluate the difference in the mean values among frequencies and P values below 0.05 were considered significant. NS: not significant, *p<0.001. Results are expressed as mean±S.D.

Table 3. Average of the highest threshold during the follow-up period

There were significant differences between hearing level at low and at middle frequencies. The hearing loss rate was the proportion of patients with hearing loss over 30dB HL at each frequency. The t-test was used to evaluate the difference in the mean values among frequencies and P values below 0.05 were considered significant. NS: not significant, *p<0.05. Results are expressed as mean±S.D.

  • View full-size image.
  • Fig. 2. 

    The mean value of the threshold fluctuation range. Closed circles indicate the mean pure-tone thresholds. Error bars indicate the standard deviation of the means.

Table 4. Average of the threshold fluctuation range during the follow-up period
Low frequencyMiddle frequencyHigh frequency
Threshold fluctuation range (dB)13.0±6.510.0±5.312.2±6.1
Fluctutation rate (%)724264

There was no significant difference among hearing levels at each frequency. Fluctuation rate was the proportion of patients with hearing fluctuations over 10dB HL at each frequency. The t-test was used to evaluate the difference in the mean values among frequencies and P values below 0.05 were considered significant. Results are expressed as mean±S.D.

Table 5. Average threshold worsening between the first and last visits
Low frequencyMiddle frequencyHigh frequency
Threshold worsening (dB)4.5±3.63.0±2.83.9±3.4
Worsening rate (%)844

There was no significant difference among hearing level at each frequency. The worsening rate is the proportion of patients with hearing worsening over 10dB HL at each frequency. The t-test was used to evaluate the difference in the mean values among frequencies and P values below 0.05 were considered significant. Results are expressed as mean±S.D.

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4. Discussion 

Fortunately, in this study, no school-age children with JUPHL were grade failures, needed additional educational assistance, or showed perceived behavioral issues in the classroom. Some school-age children sit in the best listening position of their classrooms for a better signal-to-noise ratio. However, as reported by Ruscetta et al. [12], even in the best listening conditions, children with unilateral hearing loss require a better signal-to-noise ratio than do children with normal hearing to perform equally well, suggesting that preferential seating alone may not provide enough benefit for these children. We must consider speech recognition abilities of children with JUPHL carefully.

In this study, we investigate contralateral hearing in patients with JUPHL because if the contralateral ear has hearing loss, the patients can develop bilateral hearing loss. Even though no patient complained of contralateral hearing at the first visit, their audiogram configurations showed mild peak patterns with slight low and high tone loss. In the worst hearing condition, pure tone thresholds were still lower than 30dB HL on average. Concerning fluctuation of the threshold, it is one of the characteristic features in patients with endolymphatic hydrops. Even though the mean value of the threshold fluctuation was 13dB at the low frequencies, the incidence was 72%. This incidence is surprisingly high. Fortunately, hearing worsening between the first and last visits was less than 10dB on average. These results suggest that we have to follow-up patients with JUPHL for a long time, if possible, throughout their lives.

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References 

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PII: S1871-4048(06)00052-9

doi:10.1016/j.pedex.2006.04.008

International Journal of Pediatric Otorhinolaryngology Extra
Volume 1, Issue 3 , Pages 192-195, September 2006

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