Stable long-term outcomes after cochlear implantation in subjects with TMPRSS3 associated hearing loss: a retrospective multicentre study.

BACKGROUND: The spiral ganglion hypothesis suggests that pathogenic variants in genes preferentially expressed in the spiral ganglion nerves (SGN), may lead to poor cochlear implant (CI) performance. It was long thought that TMPRSS3 was particularly expressed in the SGNs. However, this is not in line with recent reviews evaluating CI performance in subjects with TMPRSS3-associated sensorineural hearing loss (SNHL) reporting overall beneficial outcomes. These outcomes are, however, based on variable follow-up times of, in general, 1 year or less. Therefore, we aimed to 1. evaluate long-term outcomes after CI implantation of speech recognition in quiet in subjects with TMPRSS3-associated SNHL, and 2. test the spiral ganglion hypothesis using the TMPRSS3-group. METHODS: This retrospective, multicentre study evaluated long-term CI performance in a Dutch population with TMPRSS3-associated SNHL. The phoneme scores at 70 dB with CI in the TMPRSS3-group were compared to a control group of fully genotyped cochlear implant users with post-lingual SNHL without genes affecting the SGN, or severe anatomical inner ear malformations. CI-recipients with a phoneme score ≤ 70% at least 1-year post-implantation were considered poor performers and were evaluated in more detail. RESULTS: The TMPRSS3 group consisted of 29 subjects (N = 33 ears), and the control group of 62 subjects (N = 67 ears). For the TMPRSS3-group, we found an average phoneme score of 89% after 5 years, which remained stable up to 10 years post-implantation. At both 5 and 10-year follow-up, no difference was found in speech recognition in quiet between both groups (p = 0.830 and p = 0.987, respectively). Despite these overall adequate CI outcomes, six CI recipients had a phoneme score of ≤ 70% and were considered poor performers. The latter was observed in subjects with residual hearing post-implantation or older age at implantation. CONCLUSION: Subjects with TMPRSS3-associated SNHL have adequate and stable long-term outcomes after cochlear implantation, equal to the performance of genotyped patient with affected genes not expressed in the SGN. These findings are not in line with the spiral ganglion hypothesis. However, more recent studies showed that TMPRSS3 is mainly expressed in the hair cells with only limited SGN expression. Therefore, we cannot confirm nor refute the spiral ganglion hypothesis.

Velopharyngeal dysfunction and 22q11.2 deletion syndrome: a longitudinal study of functional outcome and preoperative prognostic factors.

OBJECTIVE: To describe the effect of time after velopharyngoplasty on outcome and to search for preoperative prognostic factors for residual hypernasality in patients with 22q11.2 deletion syndrome. DESIGN: Retrospective chart review. SETTING: Tertiary hospital. PATIENTS: Patients with 22q11.2 deletion syndrome and velopharyngeal dysfunction who underwent a primary (modified) Honig velopharyngoplasty between 1989 and 2009. MAIN OUTCOME MEASURES: Clinically obtained perceptual and instrumental measurements of resonance, nasalance, and understandability before and after velopharyngoplasty. RESULTS: Data were available for 44 of 54 patients (81% follow-up), with a mean follow-up time of 7.0 years (range, 1.0 to 19.4 years). During follow-up, 24 (55%) patients attained normal resonance and 20 (45%) had residual hypernasality or underwent revision surgery. Mean postoperative nasalance and understandability scores were closer to the norm than mean preoperative scores were (2.0 versus 5.5 standard deviations for the normal passage, 1.3 versus 8.1 standard deviations for the nonnasal passage, and score 2.3 versus 4.1 understandability). Serial measurements revealed that hypernasality only resolved an average of 5 years after surgery, and three patients whose resonance initially normalized later relapsed to hypernasality. Gender, age at surgery, lateral pharyngeal wall adduction, velar elevation, presence of a palatal defect, previous intravelar veloplasty, nasalance, understandability, adenoidectomy, hearing loss, and IQ were not able to predict poor outcome following primary velopharyngoplasty (all p > .05). CONCLUSIONS: In this chart review of patients with 22q11.2 deletion syndrome and velopharyngeal dysfunction, residual hypernasality persisted in many patients after velopharyngoplasty. None of the preoperative factors that were studied had prognostic value for the outcome.

Possible mechanisms and gene involvement in speech problems in the 22q11.2 deletion syndrome.

SUMMARY: The 22q11.2 deletion syndrome represents a contiguous gene syndrome with a highly variable phenotype. To date, over 180 clinical features have been described. Studies have been done in order to identify the responsible genes. Several candidate genes such as TBX1 and COMT seem to be important in the development of the phenotype. One of the prevalent and serious problems encountered by patients with the 22q11.2 deletion is difficulty with speech. This may be due to a number of factors such as adenoid hypoplasia, muscle hypotonia, platybasia, upper airway asymmetry, and neuroanatomical abnormalities. The complex interaction of these factors leads to less favourable results after surgery to correct velopharyngeal insufficiency. This article offers a theoretical overview and proposes future research to investigate which factors are indeed responsible for the speech problems encountered by patients with the 22q11.2 deletion and identify responsible genes.