Familial Mondini dysplasia

Hearing preservation with a slim modiolar cochlear implant in a pediatric cohort

OBJECTIVES

Recent cochlear implant (CI) electrodes are designed to be atraumatic to inner ear structures. Studies in adults have demonstrated improved hearing preservation rates with the CI532/632 electrode, but none have examined this in children. Our objective is to describe the hearing preservation rate with CI532/632 in pediatric patients and determine factors that influence hearing preservation.

METHODS

We conducted a retrospective cohort study of children undergoing CI over a three-year period. Inclusion criteria were: CI with the 532/632 electrode, presence of pre-operative low frequency hearing defined by pure tone average (PTA) of ≤80 dB at 250 Hz or at the average of 250 and 500 Hz, and post-operative unaided audiometry. Other data collected included demographics, otologic history, imaging, and surgical details.

RESULTS

A total of 13 patients and 15 ears were included. Hearing was preserved in 10/15 (66%) ears at an average follow-up of 6 months, similar to that reported in the adult literature. Patients with preserved hearing post-operatively were more likely to have a positive family history of hearing loss. There was a trend towards patients with anatomic inner ear abnormalities being more likely to lose hearing after CI, but this was not statistically significant. Pre-operative thresholds were not predictive of hearing preservation. Patients with preserved hearing had a significantly smaller shift in thresholds after cochlear implantation. Therefore, hearing preserved and non-preserved groups differed more by the magnitude of change in threshold, rather than their preoperative threshold. Other factors such as age, sex, surgeon, and surgery duration were not associated with hearing preservation.

CONCLUSION

This study describes low frequency hearing preservation after pediatric CI532/632 implantation. The hearing preservation rate in our cohort was consistent with that reported in the adult literature. Our data suggest that preoperative thresholds do not solely determine which patients will go on to experience hearing preservation. We believe this will aid surgeons with patient-specific device selection and counseling potential pediatric CI recipients with preserved hearing.

Familial nonsyndromic hearing loss with incomplete partition type II caused by novel DSPP gene mutations

BACKGROUND

Familial nonsyndromic hearing loss (NSHL) with incomplete partition type II (IP-II) is a very rare condition.

AIMS/OBJECTIVES

To determine the audiological feature, inheritance patterns and genetic etiology of familial NSHL with IP-II in a Chinese family with eight family members.

MATERIAL AND METHODS

Clinical data were collected from all eight family members, selected deafness genes were sequenced in proband and whole genome sequencing of seven family members was performed.

RESULTS

The proband were a pair of male nonidentical twins (III:1, III:2). Three patients in this family, including the twins and their father (II:1), were diagnosed with bilateral NSHL with IP-II, and no mutation was found in the genes of SLC26A4, GJB2, GJB3, mitochondrial 12S rRNA, and MITF. Whole genome sequencing data indicated de novo mutations of the gene DSPP, c.3085A > G and c.3087C > T, which resulted in p.N1029D and co-segregated with deafness phenotype, were the underlying genetic etiology.

CONCLUSION AND SIGNIFICANCE

Familial NSHL with IP-II is extremely rare. In this family, de novo DSPP gene mutations, were considered to be the most probable genetic etiology. And this is the first report to reveal DSPP gene mutations leading to familial NSHL with IP-II.

Goiter and hearing impairment: A case of a male patient with Pendred syndrome

Pendred syndrome is a rare genetic disease that causes a disturbance in thyroid hormone synthesis, which results in thyroid dysfunction and the development of goiter and sensorineural deafness. The present report describes the case of a young euthyroid male, who developed a large goiter and hearing impairment, despite no family history of these conditions. A left lobectomy and a subtotal right lobectomy were performed, and the patient was administered permanent hormone replacement therapy with thyroxine. Patients with Pendred syndrome exhibit distinct clinical features and the mechanisms associated with the molecular genetics of this disease have been clarified. Thus, gene detection is considered to be a reliable diagnostic method. Certain patients require surgical intervention in order to relieve the symptoms. Misdiagnosis can be significantly reduced by increasing the understanding of Pendred syndrome.

Specificity of SLC26A4 mutations in the pathogenesis of inner ear malformations

The traditional hypothesis concerning the pathogenesis of inner ear malformations holds that various types of malformations represent different stages of developmental arrest during embryogenesis. In order to verify this hypothesis, we surveyed mutations in the SLC26A4(PDS) gene, which were documented to cause enlarged vestibular aqueduct (EVA) and Mondini's dysplasia (incomplete partition of the cochlea), in 35 families with various types of inner ear malformations. In 25 families, the probands showed EVA or Mondini's dysplasia as the main temporal bone abnormalities, whereas the probands in the remaining 10 families revealed other types of malformations. In total, 7 mutated SLC26A4 alleles, including 6 missense mutations (A372V, A387V, T410M, S448L, T721M, and H723R) and 1 splice site mutation (IVS7-2A-->G), were detected. All mutated alleles segregated the malformations of EVA and Mondini's dysplasia, whereas no mutated alleles were found in the 10 probands with other types of malformations. SLC26A4 mutations were found in 22 of the 25 probands with EVA or Mondini's dysplasia, indicating that these might be specific to the development of Mondini's dysplasia and EVA. It is inferred that the pathogenetic mechanisms of the various malformations essentially differ, although their radiological findings appear to follow a continuum of morphological changes.

Vertigo and dysequilibrium with associated hearing loss

There are numerous disorders that can present with hearing loss and vertigo or dysequilibrium. The combination of vertigo and imbalance associated with hearing loss are symptoms suggestive of a peripheral vestibular disorder. This article summarizes presentation, diagnosis, and treatment of the various common and rare peripheral vestibular disorders that can present with these symptoms.

Clinical evaluation of the hearing-impaired infant

Early identification of hearing loss and rapid rehabilitative intervention are the two key elements that will give an infant the best chance to develop normal speech and allow the family members to make appropriate adjustments that will enhance communication in the home environment. Hearing loss in an infant may be only one feature of a syndromic disorder, and the physician must aspire to diagnose and treat the entire dysfunction. While a limited laboratory evaluation and appropriate referrals to related specialties are helpful, a comprehensive history and a complete physical examination are the most effective means to identify syndromic hearing loss and to direct future evaluation and therapy.