Blog Archives

High frequency of autosomal-recessive DFNB59 hearing loss in an isolated Arab population in Israel

Autosomal-recessive nonsyndromic hearing impairment (DFNB) is usually of prelingual onset with a moderate to profound degree of hearing loss. More than 70 DFNB loci have been mapped and ∼40 causative genes have been identified. Nonsyndromic hearing impairment caused by mutations of DFNB59 (encoding pejvakin) has been described in a couple of families in which affected individuals presented with either auditory neuropathy or hearing loss of cochlear origin. We have identified and clinically evaluated three consanguineous families of Israeli Arab origin with prelingual nonsyndromic hearing impairment and absent otoacoustic emissions with a total of eight affected individuals. All the families originate from the same village and bear the same family name. We have identified a c.406C>T (p.R136X) nonsense mutation in the DFNB59 gene in affected individuals from these families. Among the inhabitants of the village, we found an exceptionally high carrier frequency of approximately 1 in 12 individuals (7/85; 8.2%). The high prevalence of hearing impairment can be explained by a founder effect and the high consanguinity rate among the inhabitants of this village.

from Clinical Genetics

Advertisements

Viagra deafness—Sensorineural hearing loss and phosphodiesterase-5 inhibitors

Conclusion:
There is increasing evidence that PDE-5 inhibitors may induce sensorineural hearing loss via plausible physiological mechanisms. There needs to be more awareness of this disabling side effect among healthcare professionals responsible for prescribing this drug.

from The Laryngoscope

An improved cochlear implant electrode array for use in experimental studies

Experimental studies play an important role in establishing the safety and efficacy of cochlear implants and they continue to provide insight into a new generation of electrode arrays and stimulation strategies. One drawback has been the limited depth of insertion of an electrode array in experimental animals. We compared the insertion depth and trauma associated with the insertion of Cochlear Ltd’s Hybrid-L (HL) array with a standard 8 ring array in cat cochleae. Both arrays were inserted into cadaver cochleae and an X-ray recorded their anatomical location. The implanted cochlea was serially sectioned and photographed at 300μm intervals for evidence of electrode insertion trauma. Subsequently two cats were chronically implanted with HL arrays and electrically-evoked potentials recorded over a three month period. Mean insertion depth for the HL arrays was 334.8° (SD = 21°; n = 4) versus 175.5° (SD = 6°; n = 2) for the standard array. This relates to ˜10.5 mm and 6 mm respectively. A similar insertion depth was measured in a chronically implanted animal with a HL array. Histology from each cadaver cochleae showed that the electrode array was always located in the scala tympani; there was no evidence of electrode insertion trauma to the basilar membrane, the osseous spiral lamina or the spiral ligament. Finally, evoked potential data from the chronically implanted animals exhibited significantly lower thresholds compared with animals implanted with a standard 8 ring array, with electrical thresholds remaining stable over a three month observation period. Cochlear Ltd’s HL electrode array can be safely inserted ˜50% of the length of the cat scala tympani, placing the tip of the array close to the 4 kHz place. This insertion depth is considerably greater than is routinely achieved using a standard 8-ring electrode array (˜12 kHz place). The HL array evokes low thresholds that remain stable over three months of implantation. This electrode array has potential application in a broad area of cochlear implant related research.

from Hearing Research

Children with bilateral cochlear implants: variability in the results

We reviewed data from a sample of 30 children (aged 1-12 years old) with bilateral implants enrolled in an integration school in Madrid. This study was prompted by the observation of differences in a small, but significant, number of children.

The variables analyzed were age at implantation, differences in the interval between the two implantations, choice of the first ear to undergo implantation, and the use or non-use of a contralateral hearing aid between the first and second implantations.

None of these variables was clearly related to difficulties but there were some indications that age at implantation and having always used a hearing aid in the ear with the later implant may be important factors.

Despite the generally favorable results, this study stresses the need to bear in mind individual variations that naturally concern families and education professionals.

The final section of the article discusses the implications of sequential bilateral implantation of cochlear implants in clinical practice in speech therapy.

from Revista de Logopedia, Foniatría y Audiología

Social perception of deafness in the educational environment: designing an evaluation questionnaire

This article analyzes the results of a pilot study of the application of a proposed questionnaire on social perception of deafness in the primary and secondary education setting. The first part of the article discusses the rationale for evaluating the integration of deaf girls and boys in mainstream schools and the suitability of the questionnaire for this purpose.

The second part describes the process of drafting the items covering aspects such as the quality of communication, social perceptions of deafness from the point of view of the hearing person, deaf students’ self-esteem and the degree of social integration they can attain.

from Revista de Logopedia, Foniatría y Audiología

Developmental Plasticity Of Auditory Cortical Inhibitory Synapses

Functional inhibitory synapses form in auditory cortex well before the onset of normal hearing. However, their properties change dramatically during normal development, and many of these maturational events are delayed by hearing loss. Here, we review recent findings on the developmental plasticity of inhibitory synapse strength, kinetics, and GABAA receptor localization in auditory cortex. Although hearing loss generally leads to a reduction of inhibitory strength, this depends on the type of presynaptic interneuron. Furthermore, plasticity of inhibitory synapses also depends on the postsynaptic target. Hearing loss leads reduced GABAA receptor localization to the membrane of excitatory, but not inhibitory neurons. A reduction in normal activity in development can also affect the use-dependent plasticity of inhibitory synapses. Even moderate hearing loss can disrupt inhibitory short- and long-term synaptic plasticity. Thus, the cortex did not compensate for the loss of inhibition in the brainstem, but rather exacerbated the response to hearing loss by further reducing inhibitory drive. Together, these results demonstrate that inhibitory synapses are exceptionally dynamic during development, and deafness-induced perturbation of inhibitory properties may have a profound impact on auditory processing.

from Hearing Research

Bone-anchored hearing aids in children and young adults: the Freeman Hospital experience

Conclusion: The use of bone-anchored hearing aids and Softband results in significant improvements in quality of life for children and young adults with hearing impairment. There is significant under-utilisation of bone-anchored hearing aids in children with skull and congenital abnormalities, and we would advocate bone-anchored hearing aid implantation for these patients.

from the Journal of Laryngology and Otology

Auditory measurements in parents of individuals with autosomal recessive hearing loss

CONCLUSION: the DPOAE were more effective, in comparison to the pure tone audiometry, to detect auditory differences between the groups. More studies of this type are necessary to confirm the observed results.

from Pró-Fono Revista de Atualização Científica

Cochlear implant: correlation of nerve function recovery, auditory deprivation and etiology

CONCLUSION: there was no statistically significant correlation between the recovery function and factors such as etiology, time of auditory deprivation and time of hearing aid use prior to CI.

from Pró-Fono Revista de Atualização Científica

Phonological, Orthographic, and Syntactic Awareness and their Relation to Reading Comprehension in Prelingually Deaf Individuals: What Can We Learn from Skilled Readers?

This study seeks to provide new insight into the phonemic, orthographic, and syntactic awareness of individuals with prelingual deafness and the way those contribute to reading. Two tests were used: one designed for the assessment of phonemic/orthographic awareness (PO/OA) and another examining reading comprehension (RC) in contexts where prior knowledge was either helpful or not. Participants were 83 prelingually deaf individuals (DIs): 21 primary school, 36 high school, and 26 university students. The control group consisted of 85 hearing individuals (HIs) from parallel education levels (29 primary school, 29 high school, 27 university). Contrary to predictions made by current reading theories, findings imply that the failure of DIs to develop sensitivity to the phonological properties of words may not underlie their reading difficulties. Rather, this weakness seems to reflect a processing deficit at the supra-lexical (sentence) level where the final meaning of single words is elaborated by its integration based upon syntactic (structural) knowledge.

from the Journal of Developmental and Physical Disabilities

Voice discrimination in cochlear-implanted deaf subjects

The human voice is important for social communication because voices carry speech and other information such as a person’s physical characteristics and affective state. Further restricted temporal cortical regions are specifically involved in voice processing. In cochlear implanted deaf patients, the processor alters the spectral cues which are crucial for the perception of the paralinguistic information of human voices. The aim of this study was to assess the abilities of voice discrimination in cochlear-implant (CI) users and in normal-hearing subjects (NHS) using a CI simulation (vocoder). In NHS the performance in voice discrimination decreased when reducing the spectral information by decreasing the number of channels of the vocoder. In CI patients with different delays after implantation we observed a strong impairment in voice discrimination at time of activation of the neuroprosthesis. No significant improvement can be detected in patients after two years of experience of the implant while they have reached a higher level of recovery of speech perception, suggesting a dissociation in the dynamic of functional recuperation of speech and voice processing. In addition to the lack of spectral cues due to the implant processor, we hypothesized that the origin of such deficit could derive from a crossmodal reorganization of the temporal voice areas in CI patients.

from Hearing Research

Children with cochlear implants and developmental disabilities: A language skills study with developmentally matched hearing peers

The number of children receiving cochlear implants (CIs) with significant disabilities in addition to their deafness has increased substantially. Unfortunately, children with additional disabilities receiving CIs have largely been excluded from studies on cochlear implant outcomes. Thus limited data exists on outcomes in this population to guide pre-implant counseling for anticipated benefits. The study objectives were: (1) evaluate differences in post-cochlear implant language skills between children with cochlear implants and developmental disabilities and age/cognitively matched controls; (2) quantify possible discrepancies between language level and cognitive level. Fifteen children with a developmental disability who received a CI were matched 1:1 on nonverbal cognitive ability and age to hearing controls. Language was evaluated using Preschool Language Scale-IV and reported as language quotients. Multivariable mixed models for matched pairs analyzed differences in language levels between groups. No significant differences were seen between CI and control groups regarding insurance, maternal education, or family income level. Results of the multivariable models indicated that compared to matched controls, the CI group had significantly lower mean receptive (24.6 points, p = 0.002) and mean expressive (21.9 points, p = 0.001) language quotients after controlling for confounders such as number of therapies and weekly hours in therapy. Significant discrepancies between language level and cognitive level were seen among CI participants only. Compared to age- and cognitively matched controls, children with CIs had significantly lower language levels with delays disproportionate to their cognitive potential. Mechanisms behind this performance-functional gap need to be understood to deliver appropriate intervention strategies for this special population.

from Research in Developmental Disabilities

Assessing deaf and hearing children’s communication in Brazil

In Brazil there are no specific tests for either signed and/or spoken language for deaf children. A protocol evaluating communicative abilities independent of modality of communication (sign language or spoken language), and comprising assessments of a) pragmatic profile; b) modality of communication and linguistic level; c) complexity ofcommunication; and d) style and efficacy of communication between parent-child was administered to 127 deaf and hearing children. The children, aged 3 to 6 years old, were distributed in three groups: 20 with severe hearing loss, 40 with profound hearing loss and 67 normally hearing. Deaf children were found to be delayed, independent of their linguistic level and preferred modality of communication. The protocol in this study proved to be an useful instrument for gathering relevant information about the three groups of preschool children’s communicative abilities, and particularly suitable for use in countries where standardized assessments are not available.

from the Journal of Communication Disorders

Tense marking by Brazilian deaf signers

CONCLUSION: the deaf participants of the study presented and adequate use of tense markers in most of the sentences produced using Brazilian sign language, however difficulty was observed when using written Portuguese.

from Pró-Fono Revista de Atualização Científica

Implants and ethnocide: learning from the cochlear implant controversy

This paper uses the fictional case of the ‘Babel fish’ to explore and illustrate the issues involved in the controversy about the use of cochlear implants in prelinguistically deaf children. Analysis of this controversy suggests that the development of genetic tests for deafness poses a serious threat to the continued flourishing of Deaf culture. I argue that the relationships between Deaf and hearing cultures that are revealed and constructed in debates about genetic testing are themselves deserving of ethical evaluation. Making good policy about genetic testing for deafness will require addressing questions in political philosophy and anthropology about the value of culture and also thinking hard about what sorts of experiences and achievements make a human life worthwhile.

from Disability & Society