Prognostic validity of auditory brainstem evoked response screening in newborn infants

The effectiveness of the auditory brainstem evoked response (ABR) test as a screening test for permanent hearing loss in neonates is examined in 32 published studies including 4,945 infants. Follow-up studies validating initial test failure were available for only 658 infants. Significant differences in methodology exist among these studies, and these differences may have affected their outcomes. Despite this problem, data from these studies were pooled, and they revealed that 16.5 per cent of neonates failed the initial ABR test. Of these, 5.1 per cent were later confirmed to be hearing-impaired or otherwise neurologically impaired. This implies that many of the false-positive results occurred in neonates who had transient disorders, such as conductive hearing loss or neurologic abnormalities, at the time of the screening test, or that the pass/fail criterion was too stringent. Lack of data on false-negative results or the rate of correct identification of normal infants makes it impossible to assess the sensitivity of the test accurately. Firm estimates of the prognostic validity of the neonatal ABR screening in identifying the impaired population can be achieved only when the actual impairment rate can be estimated, and when the distributions of ABR latencies and thresholds for both normal and impaired populations are known. These data could be obtained by following groups of high-risk infants longitudinally and by pooling raw ABR data from the normal and impaired populations that are collected using standardized procedures and similar equipment.     

Detection of aminoglycoside ototoxicity by high-frequency auditory evaluation: selected case studies

A practical monitoring procedure utilizing frequencies higher than those tested by conventional audiometry for the detection of ototoxicity has the potential for preventing or minimizing irreversible communication deficits in patients receiving aminoglycoside antibiotic therapy. If ototoxicity produced by these drugs could be detected before it progresses to involve the frequencies essential for communication, it might be possible to lower the dose or to change to another antibiotic to prevent a permanently handicapping hearing impairment. From a total of 77 patients monitored by serial audiograms, three case studies illustrate the various types of auditory sensitivity changes observed with high-frequency audiometry. Ototoxicity was generally detected by high-frequency auditory testing before it could be detected by conventional audiometric procedures. These cases demonstrate the utility of monitoring audition at frequencies higher than those tested conventionally in patients receiving aminoglycoside antibiotics.