Don W. Worthington

Some comparisons between auditory brain stem response thresholds, latencies, and the pure-tone audiogram.

Aspects of auditory brain stem responses (ABR) and pure-tone behavioral audiograms were compared in patients with cochlear hearing loss. Click-evoked ABR thresholds appeared to be related most closely to the audiometric thresholds at 2000 and 4000 Hz, with relatively poor agreement at either 1000 or 8000 Hz. These results were related to the amplitude spectrum of the eliciting stimulus. The slope of the wave V latency-intensity function appeared to be related to the configuration of the hearing loss. Patients with high-frequency sensorineural losses had steeper slopes than normal subjects, whereas patients with flat sensonneural losses had shallower slopes. These results were related to the principle that response latency is determined by the cochlear region that predominates the ABR for different stimulus intensities.

Quantifiable hearing and no ABR: paradox or error?

Reports concerning the inability to record at least wave V of the ABR in patients with quantifiable hearing have generally been confined to patients with demonstrable neurological diseases. Four patients with no neurological evidence of brainstem dysfunction in whom the ABRs were either absent or showed thresholds inappropriate for the audiometric configurations are presented.

Noise-induced hearing loss in children

Occupational noise exposure remains the most commonly identified cause of noise‐induced hearing loss (NIHL), but potentially hazardous noise can be encountered during leisure‐time activities. NIHL in the pediatric population has received scant attention. This study focuses on 114 children and adolescents (ages 19 and under: 90.3% males) who were diagnosed as having probable NIHL on the basis of history and audiometric configuration. In 42 children the loss was unilateral, while the remaining 72 had sensorineural losses of varying configurations in the contralateral ear. The mean age of referral for evaluation was 12.7 years (range 1.2 to 19.8, SD 4.21), although 26% of these losses were diagnosed in children aged 10 years and younger. Such irreversible, but potentially preventable losses, should be given high priority on the public health agenda. Comprehensive, age‐appropriate educational programs must be developed for elementary and secondary students and their parents to acquaint them with potentially hazardous noise sources in their environment.

Fluctuating and/or progressive sensorineural hearing loss in children.

Sensorineural hearing loss (SNHL) which is sudden in onset, fluctuating, and/or progressive complicates medical management, hearing aid selection, and individualized educational planning for a hearing‐impaired child. In spite of multidisciplinary evaluation and intervention, a gradual decrease in auditory acuity may continue unabated in a significant number of cases. Intercurrent middle ear disease and inconsistent audiologic technique can account for threshold variation in some cases. The study population consisted of 229 children (132 boys; 97 girls) aged 1 to 19.9 years at first audiogram which revealed at least a mild degree of sensorineural hearing loss in one or both ears (35 unilateral), and who demonstrated threshold variation of 10 dB or more in at least one ear at one or more of the standard audiometric test frequencies (250, 500, 1000, 2000, 4000, and 8000 Hz) and were without concurrent middle ear disease (mean length of follow‐up, 4.9 years; mean number of audiograms, 10.3). Of 365 ears demonstrating threshold variation of 10 dB or more, 22 (6%) had purely progressive losses without intercurrent upward fluctuation, 208 (57%) had fluctuating thresholds with gradually progressive losses, and 135 (37%) had intermittent threshold fluctuation without permanent deterioration. The probability of contralateral threshold fluctuation if one ear fluctuated was 0.91, while the probability of contralateral progressive SNHL if one ear progressed was 0.67. Demographic data, presumptive etiology, degree of initial SNHL, audiometric configuration, and symmetry of threshold variation were considered as potential predictors of the likelihood of threshold fluctuation and/or progression.

Severe versus profound sensorineural hearing loss in children: Implications for cochlear implantation†

The advent of cochlear implants for children has stimulated interest in the specific sensory deficits and communicative capabilities of children with severe or profound bilateral sensorineural hearing loss. Appropriate management of these children and their families requires an appreciation of the multifaceted developmental and educational challenges confronting deaf children, even after cochlear implantation. Evaluation results from 200 children with bilateral sensorineural deafness (63 severe/137 profound, anacusic, and fragmentary) reveal significant differences between these two subpopulations. Within the profoundly impaired group, important differences were also noted in the childrens ability to benefit from conventional amplification, depending on residual hearing at or above 1000 Hz. Strategies for assessing auditory function and aided benefit in severely and profoundly hearing‐impaired children must involve a pediatric test battery, serial evaluations, and parental cooperation/support. When selecting candidates for cochlear implantation, it is inappropriate to categorize severely hearing‐impaired children with those children having profound sensorineural losses. Even profoundly impaired populations are not homogeneous, and rehabilitation potential with conventional amplification must be determined on an individual basis, over time.

Cerebrospinal fluid parameters and auditory brainstem responses following meningitis

Auditory brainstem responses were measured in 94 children under 24 months of age immediately following treatment for bacterial meningitis. Evidence of peripheral hearing loss (thresholds of 30 dB HLn or greater) was found in 47% of the patients. In addition, 9% had prolonged interwave latencies, indicating the possible presence of retrocochlear pathology. Other clinical data were examined as well. CSF glucose concentration correlated with both the presence and magnitude of hearing loss (as measured by auditory brainstem responses). Magnitude of hearing loss also was associated with the presence of seizures. Although all children recovering from meningitis should be assessed for hearing loss, those who have had low CSF glucose concentrations and seizures appear to be at high risk.

The effects of tocainide on audiological and electrophysiological responses in humans

This study reports on the systematic audiological evaluation of 18 cardiac patients receiving tocainide, an orally administered cardiac antiarrhythmic agent. The results of an audiological site of lesion test battery were compared with auditory brain stem response (ABR) measures. Of 35 ears tested, 17 (48%) presented ABR findings consistent with retrocochlear pathology. Audiological signs of retrocochlear pathology occurred less frequently and often in patients in whom ABR results suggested normal hearing or cochlear hearing loss. These data demonstrate that an extraneous agent, in this case tocainide, can affect ABR transmission times and that it is important to recognize such possible effects in order to interpret ABR data appropriately.