Otolaryngology: Open Access
Open Access

Waardenburg syndrome (Ws) is a rare syndrome involving auditory-pigmented disorders passed onto the children as autosomal dominant inheritance. The mutation affects the MITF and Pax3 genes. Their general phenotype consists of white forelock, telecanthus, heterochromia iridis, and deafness. Four different types of Ws have been diagnosed. Type 1 contains dystopia canthorum. Type 2 excludes it. Type 3 involves musculoskeletal abnormalities, and Type 4 is characterized by aganglionic mega colon. Prevalence of this syndrome is 2-5% in deaf newborns [1]. Cochlear implantation is the accepted modality for rehabilitation of deaf population. The age at implantation, training methods, the device, and the presence of co-morbidities may affect the results.

Concerning the effect of Cochlear implantation (CI) in patients with Ws, very limited studies with different findings have been reported. This study was conducted to evaluate speech and hearing outcomes long after CI in Ws in comparison to control group.

We designed a retrospective case series study on all 21 congenitally deaf children labeled as Ws in two Iranian CI centers in 2014, where the control group consisted of 89 age and sex-matched autosomal dominant deaf children without any other co-morbidities. All of the cases were Persian speakers and examined three years after implantation. Cases with inner ear anomalies were excluded. Their age at operation varied from one to four years, and their preoperative exact intelligence quotient could not be evaluated at this age. We used Categories of auditory performance (CAP) for auditory and Speech intelligibility rating (SIR) for speech evaluations [2]. As the cases had been prelingually deaf, their CAP and SIR score were zero pre-operatively. CI devices of three companies (Med-El 25%, Nucleus 50% and AB 25%) were used. The Auditory verbal training (AVT) method was utilized for all of the cases [3]. Pre operation protocol consisted of Auditory brainstem response (ABR), temporal bone Computed tomography (CT), CAP and SIR evaluation. Six weeks post operation the device was fitted and then adjusted monthly for one year. CAP and SIR were evaluated and recorded yearly. Medical status in these patients were uneventful.

As the study was retrospective chart review without any intervention, our institutional ethical board approved the study without need for signed consent of parents.

Independent t-test was used to compare the results. However, according to Shapiro’s normality test, the data were not normally distributed. Although transformation is an acceptable approach to handle abnormal data, but transformation can sometimes decrease clinical comprehensiveness and applicability of results. So, we used non-parametric t-test to compare the results.

A total of 1369 children were implanted in 2005–2013 in these CI centers. There were 21 Ws children among them (1.5%). Further, 89 children were chosen as the control group. There were no significant differences in sex and age between two groups. The difference between mean CAP and mean SIR in the two groups was not significant (Table 1).

Table 1: CAP and SIR 3 years post operation (Nonparametric independent T-test).

The correlation between age at operation and CAP as well as SIR in both groups was evaluated. Finally, this evaluation was performed in all 110 cases. Correlations were insignificant at all. Non-parametric correlation test was used for analysis (Table 2).

Table 2: Correlation between age at operation and CAP and SIR (Non-parametric T-test).

In this study, Ws prevalence was 1.5% which was less than the global prevalence (2-5%) [1]. This may be a race effect. Our cases were evaluated 3 years after intervention and rehabilitation with no correlation found between age at operation, CAP, and SIR (Table 2). This means that age at operation will not affect the results in this age group. This finding is compatible with Tinnemore [4] and Pimperton [5] studies.

As mean CAP and SIR in both groups had no significant differences, we may conclude that there would be no difference in hearing and speech results between Ws children and other deaf children, i.e. they benefit as much as they do. This result is compatible with Kontorinis et al. [6], Daneshi et al. [7], and Deka et al. [8] studies. Amirsalari, et al [9], however, reported poor speech results in Ws in comparison with control group. This difference may be the result of their early study (only 1 year after surgery) and few Ws cases. In pre-operation radiological evaluation, all the cases have had normal inner ear, which obviates influencer effect on the results [9].

In this study, which was performed at least 3 years after cochlear implantation, we concluded that cochlear implantation surgery would be beneficial for Waardenburg patients and there would be no difference between Waardenburg and other non-syndromic deaf children. Gender and age at operation date would not affect the results. However, speech abilities will be affected by auditory abilities.

Authors highly appreciate New Rearing Research Center in Baqiyatallah University for their support in data collection and reviewing the article.

This study was not granted by any company and authors have not any interest.