DFNA25, a novel locus for dominant nonsyndromic hereditary hearing impairment, maps to 12q21-24.

Using linkage analysis, we identified a novel dominant locus, DFNA25, for delayed-onset, progressive, high-frequency, nonsyndromic sensorineural hearing loss in a large, multigenerational United States family of Czech descent. On the basis of recombinations in affected individuals, we determined that DFNA25 is located in a 20-cM region of chromosome 12q21-24 between D12S327 (centromeric) and D12S84 (telomeric), with a maximum two-point LOD score of 6.82, at recombination fraction.041, for D12S1030. Candidate genes in this region include ATP2A2, ATP2B1, UBE3B, and VR-OAC. DFNA25 may be the human ortholog of bronx waltzer (bv).

Hearing loss from a bicycle horn.

A 39-month-old child with previously documented normal hearing suffered acoustic trauma from a bicycle horn activated at his ear. Six days after the insult, a 4000-Hz 50-dB sensorineural hearing loss was found. This threshold improved to 30 dB HL over 6 months. The horn produces 143 dB peak SPL, a level clearly associated with a high risk for hair cell damage. This case shows the need for regulations limiting sound levels or requiring warning labels on potentially damaging toys and other recreational devices. Had a warning been provided, the parents of this child would not have bought the horn as a toy.

Objective diagnosis of otitis media in early infancy by tympanometry and ipsilateral acoustic reflex thresholds.

Otitis media in early infancy carries a high risk of recurrent otitis media and prolonged middle ear effusion. To fulfill the need for objective diagnostic methods in this age group, we investigated susceptance tympanograms and ipsilateral acoustic reflex thresholds in infants younger than 5 months of age. Tympanometry and acoustic reflex thresholds were performed with an otoadmittance meter using a 660 Hz probe tone. Tympanograms were interpreted using quantitative measures. These findings were compared with independent otoscopic diagnoses in 67 ears with middle ear effusion and 69 ears that were effusion free. Diagnoses were confirmed by tympanocentesis when clinically indicated. There was excellent agreement among otoscopy, peak tympanogram susceptance, and ipsilateral acoustic reflex thresholds (kappa 0.82 to 0.86, agreement 91% to 93%). We conclude that susceptance tympanograms and ipsilateral acoustic reflex thresholds are accurate diagnostic tests for otitis media in infants younger than 5 months of age.

Ipsilateral and contralateral acoustic reflexes in neonates.

Ipsilateral and contralateral acoustic reflexes were studied in neonates using 220 and 660 Hz probe tones and 500, 1000, 2000, and 4000 Hz activators. Activator sound pressure level was measured in all ears. Ipsilateral and contralateral reflexes were detected three times more frequently with a 660 Hz probe tone than with a 220 Hz probe tone. The maximum detection rate (76%) occurred with 1000 and 2000 Hz ipsilateral activators and the 660 probe tone. There was no significant difference between neonatal and adult ipsilateral thresholds at 500, 1000, and 4000 Hz. Neonatal intrameatal sound pressure levels for ipsilateral activators were found to be significantly higher than would be indicated from the otoadmittance meter manufacturer's specifications.

Ipsilateral acoustic reflexes in infants.

Ipsilateral acoustic reflex thresholds were studied in otoscopically normal ears of infants 2 weeks to 12 months old. Probe tones of 220 and 660 Hz and pure tone activators were used. Reflex recordings were free of activator artifact and were measured using quantitative standards. Reflexes were detected in 85% to 95% of infant ears for 500, 1,000, and 2,000 Hz activators but were present in only 76% of ears at 4,000 Hz. Median thresholds of 80 to 85 dB hearing level were obtained with all activators and both probe tones. There were no differences in proportions of reflexes obtained with the two probe tones. With a 500-Hz activator, thresholds at 220 Hz were lower than those at 660 Hz, while no threshold differences were demonstrated between probe tones at other activators. No relationship was demonstrated between age in the first year of life and presence or threshold of reflexes. Ipsilateral acoustic reflex measures have potential use in the identification of hearing loss and middle ear disease in infancy.

Congenital and postnatally acquired cytomegalovirus infections: long-term follow-up.

To determine long-term outcome of children with inapparent congenital cytomegalovirus infection, an assessment of congenitally infected children observed since birth was undertaken. Children with early postnatal acquisition of CMV infection were also evaluated. Cognitive, behavioral, neurologic, audiometric, and speech and language evaluations were performed in 48 patients, including 17 congenitally infected children, 10 children with postnatal infection, and 21 uninfected control subjects. Mean IQ of the three groups of children did not differ significantly. Behavioral, neurologic, speech and language examinations similarly failed to distinguish differences among the three groups. Audiologic abnormalities were present in four congenitally infected children, including one child with a severe unilateral sensorineural loss; in none of the children was hearing loss functionally significant. No hearing abnormalities were detected in postnatally infected children. Although inapparent CMV infection can result in audiologic sequelae, the continued lack of cognitive, behavioral, and neurologic sequelae in these school-age children reemphasizes the need to focus attention on prevention of primary maternal CMV infection to avoid the potentially devastating effects of intrauterine CMV infection.