Acquired causes of deafness in childhood

Congenital cytomegalovirus infection - a common cause of hearing loss of unknown aetiology

AIM

The aim of this study was to investigate the role of congenital cytomegalovirus (CMV) infection as a cause of various types of sensorineural hearing loss (SNHL) in a group of nonsyndromic children with otherwise unknown aetiology of hearing loss. Furthermore, the occurrence of combined congenital CMV infection and connexin 26 (Cx26) mutations was investigated.

METHODS

The dried blood spot (DBS) cards of 45 children with various degrees of hearing deficits and 46 children with severe/profound hearing loss were tested for CMV DNA with polymerase chain reaction (PCR) technique. The DBS cards of the 46 children with severe/profound hearing loss were also analysed for Cx26 mutations.

RESULTS

Of the 45 children with various degrees of hearing loss, nine were positive for CMV DNA (20%). The nine children represented severe/profound, mild and unilateral hearing loss. From the 46 children with severe/profound hearing loss, nine of 46 (20%) were positive for CMV DNA. In addition, three of the CMV DNA-positive children were carriers of mutations of Cx26.

CONCLUSION

Congenital CMV infection is a high risk factor in hearing impairment among children.

Performance of cochlear implant recipients with GJB2-related deafness

Congenital profound hearing loss affects 0.05-0.1% of children and has many causes, some of which are associated with cognitive delay. For prelingually-deafened cochlear implant recipients, the etiology of deafness is usually unknown. Mutations in GJB2 have been established as the most common cause of heritable deafness in the United States. In this report, we identify cochlear implant recipients with GJB2-related deafness and examine the performance of these individuals. Cochlear implant recipients received a battery of perceptive, cognitive, and reading tests. Neither subjects nor examiners knew the etiology of deafness in these individuals. The implant recipients were then examined for mutations in GJB2 using an allele-specific polymerase chain reaction assay, single-strand conformation polymorphism analysis, and direct sequencing. GJB2 mutations were the leading cause of congenital deafness among the cochlear implant recipients screened. Cochlear implant recipients with GJB2-related deafness read within one standard deviation of hearing controls better than other congenitally deaf cochlear implant recipients and non-cochlear implant recipients. Individuals with congenital deafness should be offered GJB2 screening. Positive results establish an etiologic diagnosis and provide prognostic, genetic, and therapeutic information. Effective rehabilitation for profoundly deaf individuals with GJB2-related deafness is possible through cochlear implantation.

Central areolar choroidal dystrophy and slowly progressive sensorineural hearing loss

Central areolar choroidal dystrophy (CACD) is a rare hereditary disorder leading to a central scotoma in middle-aged patients. Two cases of CACD in association with perceptive hearing loss are discussed. A 62-year-old male and a 51-year-old female patient complained of visual deterioration and subsequent hearing loss over several years. In addition to routine ophthalmic and otorhinolaryngological examination both patients underwent fluorescein angiography, (electro)physiological examination and audiometry examination. A demarcated area of atrophy of pigment epithelium and choriocapillaris was found in both patients. A slowly progressive sensorineural hearing loss after adolescence was found in both patients. The hearing deteriorated to such a level at middle age that hearing aids were necessary. These two cases show that CACD may be associated with perceptive hearing loss.