Development of a new outcomes instrument for conductive hearing loss.

OBJECTIVE: The objective was to design and validate a disease-specific outcomes instrument for use in conductive hearing loss (CHL). STUDY DESIGN: The study was a retrospective survey of 47 patients recently treated for CHL with either a hearing aid or surgery. Patients were tested with the newly designed instrument (the Hearing Satisfaction Scale [HSS]), previously validated hearing-specific instruments, and a generic quality-of-life instrument. SETTING: The study was performed in an academic tertiary referral center. MAIN OUTCOME MEASURES: These included test-retest reliability, internal consistency reliability, content validity, criterion validity, and construct validity of the HSS. RESULTS: Test-retest reliability (r = 0.72, p < 0.001) and internal consistency reliability were adequate (Cronbach's alpha was 0.83 and 0.74 for the two subscales of the HSS). Criterion validity for individual items was adequate (r = 0.45, p = 0.02) using audiometric data as the criterion standard. Construct validity was also high using results from other instruments; both convergent and divergent validity of the HSS was demonstrated. In addition, the HSS demonstrated the ability to differentially discriminate between subgroups when grouped by level of hearing loss. CONCLUSIONS: The HSS is a valid and reliable instrument for use in outcomes research on conductive hearing loss.

Auditory evoked potentials in Rett syndrome.

This study was designed to assess auditory function in subjects with Rett syndrome, a rare neurologic disorder that is characterized by progressive symptoms of dementia, ataxia, respiratory disorder, and communication disorder. Auditory evoked potentials, including the auditory brainstem response (ABR), middle latency response (MLR), and late vertex response (LVR), were recorded in 36 subjects with Rett syndrome. Results showed a systematic decline in auditory function from the peripheral to the central auditory system, with normal ABR in all subjects, normal MLR in 50 percent of subjects, and normal LVR in 36 percent of subjects. Results suggest that hearing sensitivity and the functional integrity of eighth nerve and auditory brainstem pathways are not affected in subjects with Rett syndrome. However, abnormality of both the MLR and LVR suggest the presence of central auditory disorder.

Auditory P300 abnormalities and leukocyte activation in HIV infection.

To evaluate whether P300 testing might serve as a screening modality for the early detection of HIV-related neuropathology, we tested 26 HIV-infected men (23 without neurologic symptoms, 2 with peripheral neuropathy, 1 with AIDS-associated dementia) and 15 controls. Although they had no overt neurologic symptoms, the P300 latency was delayed or undetectable in 30% of patients without clinically evident neurologic disease. P300 latencies did not correlate with peripheral blood CD4 T-cell count, serum quinolinic acid or p24 antigen levels, or the numbers of activated peripheral blood monocytes. Three individuals with abnormal P300 latencies had been HIV-seropositive for < or = 1 year, suggesting that delayed evoked responses detect early neurologic dysfunction. P300 responses do not predict imminent dementia. In only one previously asymptomatic individual with abnormal P300 waveforms have overt neurologic symptoms developed during a 2-year followup. Extended longitudinal studies will be necessary to define the predictive value of P300 latencies in the development of AIDS-related dementia. However, the sensitivity, quantitative nature, and speed of administration of this test suggest that it may be useful for identification of early neurologic involvement in HIV infection.

Cyclic steroid replacement alters auditory brainstem responses in young women with premature ovarian failure.

To determine the independent contributions of estradiol and progesterone to the auditory brainstem response (ABR) latency changes associated with the menstrual cycle, we obtained ABRs on young women with premature ovarian failure who were undergoing cyclic hormone replacement therapy (HRT). We evaluated the influence of cyclic HRT on the ABRs of young women in three controlled phases of the same replacement cycles: 1) no steroid replacement, 2) estrogen-only replacement (E2-only), and 3) estrogen-plus-progesterone replacement (E2-plus-P). A significantly lengthening of wave V peak latency and I-V interpeak interval was found during E2-only replacement. Despite equivalent circulating estradiol levels, both wave V peak latencies and wave I-V interpeak intervals significantly decreased during the E2-plus-P replacement phase as compared to the E2-only replacement phase. These findings are compatible with the hypothesis that estradiol potentiates secretion of the inhibitory neurotransmitter gamma-amino-butyric acid (GABA) at auditory nerve synapses, leading to delayed synaptic conduction time. Progesterone is known to blunt E2-potentiated GABA release and may antagonize its prolongation of wave V latency.

Asymmetries in topographic brain maps of auditory evoked potentials in the elderly.

We compared topographic brain maps of the middle response (MR) and late response (LR) auditory evoked potentials in two groups of elderly males. Subjects were categorized on the basis of the performance of the poorer hearing ear on the Synthetic Sentence Identification (SSI) test. Evoked potentials, obtained in response to 1000-Hz tone pips and tone bursts, were recorded under three conditions of sound stimulation:binaural (BIN), left ear only (LE), and right ear only (RE). Comparisons of the topographic brain maps generated by the two groups revealed significant asymmetry in the MR of the experimental group. LE stimulation produced a larger response over the right hemisphere, and RE stimulation produced a larger response over the left hemisphere. This asymmetry was not observed in the experimental group with binaural stimulation, or in the control group in any of the three stimulation conditions. An analogous asymmetry was not recognized in the LR in either group for any of the three sound conditions. Results are interpreted in relation to the recently proposed model of multiple middle latency generators.

Estrogen influences auditory brainstem responses during the normal menstrual cycle.

We evaluated the impact of the menstrual cycle on auditory brainstem response (ABR) latency in nine normally cycling women. Subjects (age 23-40 years) using no hormonal therapy were recruited and underwent ABR testing during four different phases of the same menstrual cycle: early follicular (cycle days 1 to 3); mid-cycle (cycle days 12 to 15); mid-luteal (cycle days 17 to 22), and premenstrual (cycle days 25-27). Cycles were verified by basal body temperature, and serum estrogen (E2), progesterone (P), and gonadotropin levels. A control group of nine women (age 23-40 years) on oral contraceptives (Nordette-28) was also studied four times during a pill cycle. Results show a significant increase in the latency of wave III and wave V peak latencies and in the I-V interpeak interval associated with a high estrogen state at the mid-cycle phase. No statistically significant variations in latency were found in the birth control pill group. These data suggest the existence of brainstem auditory neural pathways that are sensitive to fluctuations in E2 levels during the menstrual cycle.

Special hearing aid considerations in elderly patients with auditory processing disorders.

Elderly individuals often have more deficits in speech understanding than would be expected in younger individuals with the same degree of hearing loss. Such deficits may be attributed to the complex nature of age-related changes that occur throughout the central auditory nervous system and are generally referred to as auditory processing disorders. These deficits have been related to poorer performance with hearing aids, reduced satisfaction with hearing aids, and reduced prognosis for successful benefit from hearing aid use. Intervention strategies that enhance signal to noise ratio are often successful in overcoming the debilitating effects of auditory processing disorder in the elderly.

Patterns of auditory abnormality in multiple sclerosis.

This paper stresses the relatively high prevalence of auditory abnormality in multiple sclerosis. An auditory test battery consisting of the acoustic reflex (AR), the auditory brainstem response (ABR), the masking level difference (MLD) and speech audiometry (SA) was administered to 62 patients with diagnosed 'definite' multiple sclerosis. The AR showed the highest identification rate (71%). SA was next (55%), followed by the ABR (52%) and the MLD (45%). The combination of an abnormality on either AR, ABR or SA yielded a 90% identification rate. Interestingly, the combination of AR or SA or MLD yielded an 87% identification rate without any contribution from ABR.

Central presbyacusis: a longitudinal case study.

An elderly patient with presbyacusis was tested on four occasions over a 9-year interval. Although there was little change in peripheral hearing sensitivity, central auditory function declined substantially. Diminished success as a hearing aid user seemed to parallel the change in central function. Results suggest that the central changes were auditory-specific rather than generalized cognitive in origin.

Cordless telephones and acoustic trauma: a case study.

Cordless telephones have been reported to cause irreversible damage to the ear due to acoustic trauma. The present case study reports an unusual audiometric configuration associated with direct exposure to the ring from a cordless phone. Although pure-tone sensitivity was only moderately affected, speech understanding was severely compromised.

Acoustic reflex averaging.

Signal averaging techniques have been applied to acoustic reflex measurement in order to meet the need for better temporal resolution and more accurate threshold delineation. We describe an approach to reflex measurement based on a signal averaging technique designed to examine both threshold and suprathreshold characteristics of the acoustic reflex. Results indicate that: (1) many supposed reflex threshold and latency aberrations are actually amplitude aberrations that are inappropriately classified because of instrumentation constraints; (2) reflex amplitude and waveform morphology can be recorded with appropriate fidelity using a signal averaging technique; (3) problems due to absolute amplitude variability can be minimized by using an index technique to assess amplitude relationships; (4) amplitude indices are sensitive indicators of neural pathology; (5) signal averaging and suprathreshold measurement of reflex amplitude and waveform morphology promise to enhance the sensitivity of acoustic reflex measurement.

Evaluation of the minimal auditory capabilities (MAC) test in prelingual and postlingual hearing-impaired adults.

The Minimal Auditory Capabilities (MAC) battery was used to evaluate the auditory performance of nine postlingual and ten prelingual adults with severe to profound hearing loss. Results suggest that degree of hearing loss overrides relative language skills as the primary factor affecting performance. The MAC battery appears promising as a tool for evaluating and monitoring both prelingual and postlingual adults using conventional hearing aids or cochlear implants.

The human acoustic tensor tympani reflex. A case report.

In a patient with unilateral lower motoneuron facial paralysis secondary to Bell's palsy, we evaluated the characteristics of what we believe to be an acoustically-evoked reflex contraction of the tensor tympani muscle. Ipsilateral stimulation of the involved ear yielded a pattern of impedance change different from the pattern characterizing normal stapedius muscle contraction. Threshold of the reflex was elevated, amplitude was large and variable, onset latency was greater, onset rise was more gradual, and offset decay was more rapid. Contralateral stimulation, with probe in the involved ear, failed to elicit the reflex contraction. Upon return of facial nerve function, the normal stapedius reflex contraction reappeared in response to both ipsilateral and contralateral stimulation.

Effect of ketamine on the stapedius reflex in the squirrel monkey.

We evaluated the effect of ketamine hydrochloride on the acoustically elicited stapedius reflex of squirrel monkeys. After intramuscular injection, in the presence of normal tympanometry, the amplitude of the contralateral stapedius reflex was severely depressed, even at low, preanesthetic dose levels. Possible mechanisms for the mediation of this unexpected effect are discussed.

Development of a dichotic sentence identification test for hearing-impaired adults.

Third-order synthetic sentences were aligned to make them suitable for dichotic presentation. These dichotic sentence materials were then administered to 14 normal listeners and 48 hearing-impaired subjects to determine the influence of peripheral hearing loss on test performance. Results suggest that the Dichotic Sentence Identification test is resistant to the influence of peripheral hearing loss until the pure-tone average of 500, 1000, and 2000 Hz exceeds approximately 50 dB. Beyond this level, degree of peripheral hearing loss limits its value for detecting central auditory disorder. Data are also provided on six persons with either confirmed or suspected lesions involving retrocochlear structures.

Relationships among auditory brain stem responses, masking level differences and the acoustic reflex in multiple sclerosis.

We report the results of a study in which we compared auditory brain stem responses (ABR), the binaural masking level difference (MLD) for a 500-Hz pure tone and acoustic reflexes in 20 patients with confirmed multiple sclerosis. Our intent was to determine whether abnormalities in the three measures were related or whether they varied independently. The results indicated that the size of the MLD varied with the integrity of wave III of the ABR. When the ABR was abnormal to the extent of lacking wave III on one or both ears, there was no release from masking and the crossed acoustic reflex was abnormal, as well. The sensitivity of the MLD to retrocochlear disorder was comparable to that of ABR, and was greater than that provided by speech audiometry or acoustic reflexes.

Superior ultra-audiometric hearing: a new type of hearing loss which correlates highly with unusually good speech in the "profoundly deaf".

This paper reports 42 severely-to-profoundly deaf subjects, 6 of whom have better hearing in the range of 8 to 14 kHz than below 8 kHz. Data on speech capabilities in these six subjects suggest that this ultra-audiometric range may contribute to their speech comprehension and control.

The cross-check principle in pediatric audiometry.

We discuss a method of pediatric audiologic assessment that employs the "cross-check principle". That is, the results of a single test are cross-checked by an independent test measure. Particularly useful in pediatric evaluations as cross-checks of behavioral test results are impedance audiometry and brain-stem-evoked response audiometry (BSER). We present five cases highlighting the value of the cross-check principle in pediatric audiologic evaluation.