Article

Auditory responses in cochlear implant users with and without GJB2 deafness.

Department of Otolaryngology-Head and Neck Surgery and the Molecular Genetics Laboratory, The Hospital for Sick Children, Toronto, Ontario, Canada.
The Laryngoscope (Impact Factor: 1.98). 02/2006; 116(2):317-27. DOI: 10.1097/01.mlg.0000199401.26626.4b
Source: PubMed

ABSTRACT It is reasonable to suppose that the pattern of sensorineural damage along the length of the cochlea depends on the etiology of a hearing loss (HL). In GJB2-related deafness, we hypothesize that gap junction deficits are uniformly distributed and will result in similar damage along the length of the cochlea as compared with non-GJB2 subjects. We assessed this by measuring patterns of neural activity and hearing from apical versus basal cochlear implant electrode regions.
This was a prospective, blind, controlled study.
Blood from 301 pediatric cochlear implant users was analyzed for mutations in GJB2 by direct sequencing. After exclusion of patients with monoallelic GJB2 mutations, associated syndromes, or risk factors for HL that were not congenital, 39 children with biallelic GJB2 mutations and 58 without GJB2 mutations were evaluated. Hearing was measured before implantation at frequencies ranging from 250 Hz to 8 kHz. After implantation, neural activity at the apical and basal ends of the implanted array was measured using electrically evoked compound action potentials of the auditory nerve (ECAPs) and evoked stapedius reflexes (ESRs).
GJB2 and non-GJB2 groups were not significantly different with respect to sex, age at implantation, duration of auditory deprivation, hearing aid use, duration of aided hearing, ear implanted, implant model, or depth of insertion (P>.05). Children with GJB2-related HL had greater similarities between low- and high-frequency residual hearing and between neural activity electrically evoked at apical and basal regions of the cochlea as compared with children with non-GJB2-related HL who demonstrated larger deficits in basal regions.
Results suggest more consistent spiral ganglion survival along the length of the cochlea in GJB2-related HL as compared with non-GJB2-related HL, which appears to involve a decreasing gradient of spiral ganglion survival from the apex to the base of the cochlea. Our findings support our premise that in GJB2-related HL, dysfunction of gap junctions likely occurs to a similar degree in the apical and basal regions of the cochlea. This knowledge might be used to customize implantable devices for patients with HL in the future.

0 Bookmarks
 · 
147 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Keratitis, ichthyosis, and deafness (KID) syndrome is a rare genodermatosis associated with mutations in the connexin 26 gene. Although characterized by this clinical triad, KID syndrome predisposes to a heterogeneous spectrum of cutaneous manifestations and complications, both infectious and neoplastic in nature. Chronic mucocutaneous candidiasis and/or superinfection of skin lesions commonly occur and warrant aggressive therapeutic intervention. Benign neoplasms, namely trichilemmal tumors, have also been reported and can herald malignant growth and invasive disease. Squamous cell carcinoma of both mucosa and skin, especially acral sites, occurs in approximately 15% of patients. The pathogenesis of KID syndrome can be at least partially explained by the role of connexin 26 in intercellular communication and carcinogenesis, but the precise mechanism of disease remains unclear. Treatment strategies, which have ranged from antifungals and antibiotics to systemic retinoids, pose an ongoing challenge given the spectrum of disease. A review of the literature, with a particular focus on infection and malignancy associated with KID syndrome, and updates on the pathogenesis of disease, is discussed.
    Journal of the American Academy of Dermatology 02/2013; · 4.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVES: To determine the long term effect of cochlear implant (CI) in children with GJB2-related deafness in Japan. METHODS: Genetic testing was performed on 29 children with CI. The speech perception in 9 children with GJB2 gene-related deafness fitted with CI was compared with those in matched 10 children who were diagnosed as having no genetic loci. The average follow-up period after CI was 55.9 months and 54.6 months, respectively. RESULTS: A definitive inherited hearing impairment could be confirmed in 12 (41.4%) of the 29 CI children, including 10 with GJB2-related hearing impairment and 2 with SLC26A4-related hearing impairment. The results of IT-MAIS, word or speech perception testing under the noise, and development of speech perception and production testing using the Enjoji scale were slightly better for the GJB2 group after CI than for the control group without statistical significant difference. CONCLUSION: The long-term results of this study show that CI is also effective in the development of speech performance after CI in Japanese children with GJB2-related hearing impairments as HL due to other etiologies.
    Auris, nasus, larynx 03/2013; · 0.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVES: We asked how thresholds of auditory activity evoked by a recent research cochlear implant, the Nucleus 513, compared with those evoked by previous generations of devices from the same manufacturer. STUDY DESIGN: Prospective repeated measures. SETTING: Tertiary pediatric hospital. PATIENTS: A total of 182 children receiving unilateral or bilateral Nucleus cochlear implants. INTERVENTIONS: Of 182 children, 39 received the N24M straight array, the oldest device in this study, 20 received the N24RCS Contour, the next device released, 57 received the 24RE Freedom, released after the N24RCS, and 66 received the N513 Leap electrode array, the newest device. MAIN OUTCOME MEASURES: Behavioral thresholds and auditory nerve response thresholds were evoked by an apical, mid-array, and basal electrode and measured in 203 ears. RESULTS: In general, auditory nerve thresholds decreased with newer devices. Responses evoked by the mid-array electrode had higher thresholds than responses to the other electrodes in most devices and highest in the operating room for the N513. Apical electrodes evoked the lowest thresholds at the level of the auditory nerve. Auditory nerve response thresholds decreased from the operating room to initial device activation with the 2 newest devices (N24RE and N513) tending to show the largest changes. Behavioral thresholds were at lowest levels for the 2 newest devices studied and, unlike auditory nerve response thresholds, decreased with age for all devices. CONCLUSION: Evolving cochlear implant electrode design significantly affects auditory thresholds, but these changes do not occur uniformly along the array.
    Otology & neurotology: official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology 01/2013; · 1.44 Impact Factor

Full-text (2 Sources)

View
7 Downloads
Available from
Jun 10, 2014