This is a prospective in-depth study of patients with sudden idiopathic sensorineural hearing loss. We found that 65% recover completely to functional hearing levels spontaneously and independent of any type of medical treatment. The majority do so within 14 days and many within the first few days. Prognosis can be predicted according to the slope of the initial audiogram (low-frequency losses do better than high-frequency losses), hearing at 8 kHz, erythrocyte sedimentation rates, in some select instances spatial disorientation symptoms, and speech discrimination scores. There was a very poor correlation between hearing and vestibular test abnormalities, except hypoactive calories. There were no correlations with age (excepting the very elderly), with antecedent respiratory infections, hypertension, diabetes, or other chronic diseases. We conclude that there is a fundamental difference in the behavior of apical and basal cochlea losses, that hearing recovery is always better at low than at high frequencies, that because of the high spontaneous recovery rates, tympanotomies seeking peri-lymph fistulas should be delayed ten days unless there is a progressive hearing loss, and that none of the current recommended treatments, especially histamine, have any effect on the outcome.

Adolescent↗

PubMedDate not supplied

Electrical stimulation of the auditory nerve in cats. Long term electrophysiological and histological results.

Each of five cats (one congenitally deaf) had Pt-Ir electrodes placed in the modiolus. Some electrodes were stimulated with a 100 micronamp, 0.25 msec balanced biphasic 50/sec pulse for 2 hours for a total of 20 to 40 hours each over periods of several months. Pre- and poststimulation measures of click-evoked N1 responses, averaged brain stem potentials, and impedances showed no long-term effects of damage to the nerves. Light microscopy showed very acceptable tissue tolerance and no evidence of damage caused by electrical stimulation. The deaf cat had about 10% residual nerve fibers which responded to stimulation.

Animals↗

PubMedDate not supplied

Pitch correlates of direct auditory nerve electrical stimulation.

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Cochlear Implants↗

PubMedDate not supplied

Accuracy of auditory brainstem evoked response with hearing level unknown.

We reported a comparison of auditory brainstem response (ABR)-estimated hearing levels with hearing levels by pure-tone audiogram for 84 ears of 42 children. Their average age was 34 months at the time of ABR and 73 months for the audiogram. Thus, all of these children were managed clinically on the basis of their ABR results. The ABR accurately predicted the pure-tone average (PTA) in 76% and was in error by no more than about +/- 10-12 dB in another 18%.

Audiometry↗

PubMedDate not supplied

Estimating eighth nerve survival by electrical stimulation.

Determining nerve survival is important in selecting patients for cochlear implants, and in predicting outcomes from such implants. In search of a possible method we deliberately destroyed nerve fibers (ganglion cells) in 17 cat cochleas to produce a range of degenerations. Months later, we electrically stimulated these ears (and seven controls) and recorded electrical ABR input-output functions. Cats with no surviving ganglion cells showed no ABR activity. Cats with 5%-10% surviving cells had ABRs which typically had normal thresholds but decreased input-output functions. The suprathreshold slopes of these input-output functions reliably predicted ganglion cell survival for all degrees of degeneration. Thus, perceptual (or electrical) threshold is a poor indicator of nerve survival. Loudness growth (or growth in the electrically-induced auditory brainstem response) is a good index of surviving ganglion cells.

Animals↗

PubMedDate not supplied

Electrically induced auditory brainstem response as a clinical tool in estimating nerve survival.

Nerve survival estimates in totally deaf ears of cats and humans can be easily obtained by auditory brainstem responses to electrical stimulation at the round window. In humans, electrically induced auditory brainstem responses require considerably more current than concurrently observed perceptual thresholds and "maximum loudnesses," and there is much variability from patient to patient. In cats, in which we also compared efficacy of stimulation sites, preliminary data analysis suggests that the scala tympani is clearly much more efficient than the round window, and the round window better than the promontory in ears with large populations of ganglion cells. In ears with no or nearly no ganglion cells, scala tympani and round window stimulations are about equal.

Animals↗

PubMedDate not supplied

Comparison of different speech processing strategies on patients receiving the same implant.

Two subjects with transcutaneously connected 8-electrode scala tympani implants were given subsets of the Minimal Auditory Capabilities test during stimulation with five speech processing strategies--two single channel and three multichannel. While there were significant (p = 0.05%) scores on some items with all types of stimulation, one subject did as well with single channel analog as with multichannel stimulation. She is an enthusiastic full-time user of single channel stimulation. The other, a nonuser of the same device, preferred (and performed better with) one of multichannel stimulation. This is an interim report because neither subject has yet had the opportunity of nonlaboratory use of the multichannel schemes.

Adult↗

PubMedDate not supplied

Histopathology of an ear after 5 years of electrical stimulation.

Four electrodes were placed in the cochlea and eighth nerve of a 57-year-old man, deafened earlier by neomycin. One electrode received over 4,000 known hours of electrical stimulation and the others fewer, but still substantial hours during extensive psychometric and speech-related testing. While tissue examination showed nerve damage in the basal turn secondary to the implant surgery, there were 18,450 surviving neurons (25,000 are normal for age). There was little or no local tissue reaction and no erosion of the electrode tips caused by electrical stimulation.

Cochlea↗

PubMedDate not supplied

Vestibulo-ocular and vestibulospinal function before and after cochlear implant surgery.

Vestibular function in cochlear implant candidates varies from normal to total absence of function. In patients with intact vestibular function preoperatively, invasion of the otic capsule places residual vestibular function at risk. Speech-processing strategies that result in large amplitude electrical transients or strategies that employ high amplitude broad frequency carrier signals have the potential for disrupting vestibular function. Five patients were tested with and without electrical stimulation via cochlear electrodes. Two patients experienced subjective vestibular effects that were quickly resolved. No long-term vestibular effects were noted for the two types of second generation cochlear implants evaluated. Histopathological findings from another patient, who had electrically generated vestibular reflex responses to intramodiolar electrodes, indicated that responses elicited were a function of several variables including electrode location, stimulus intensity, stimulus amplitude, and stimulus frequency. Differential auditory, vestibulocolic, and vestibulospinal reflexes were demonstrated from the same electrode as a function of stimulus amplitude, frequency, and duration.

Aged↗

PubMedDate not supplied

Perilymph fistula: the Stanford experience.

Seventy-eight tympanotomies were performed to determine the presence of perilymph fistulas (PLFs); of these, 51% were found. The oval and round windows of all patients were grafted, whether PLFs were present or not. Of those patients with PLFs, 64% had resolution of their major symptom; when no PLF was found, 44% had a similar outcome. We concluded that 1) PLFs often behave as if they are epiphenomena in relation to hearing and balance, 2) PLFs can be intermittent, 3) PLF surgery is disappointing for restoration of hearing in sudden hearing loss when compared to the rate of spontaneous recovery, 4) stabilizing a fluctuating or progressive loss is a more realistic goal, and 5) establishing preoperative criteria for exploration is still a problem.

Adolescent↗

PubMedDate not supplied

Increased auditory nerve acoustic sensitivity following electrical stimulation.

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Animals↗

PubMedDate not supplied

An automated hearing screening technique for newborns.

11 182 newborn infants have had their hearing thresholds screened by automatically recording crib motion before and after a test sound. An inexpensive motion transducer translates the baby(s) movements onto a multichannel strip-chart recorder (batch testing) or a single channel recorder (individual testing). Records are read off-line and scored positive if there is a change in movement within 2.5 sec after the test sound. "Passing or failing" a baby requires about one minute's clerical scoring time, and is therefore both economical and simple. We have detected 33 neonates with serious hearing losses and perhaps missed one on long-term follow-up. This amounts to a deafness incidence of 1:329 live births. In the Intensive Care/Premature nurseries the incidence is 1:62.

Auditory Threshold↗

PubMedDate not supplied

A functioning multichannel auditory nerve stimulator. A preliminary report on two human volunteers.

This paper is a brief progress report on our work with two volunteers, each with 4 electrodes placed in his auditory nerve. We are performing stimulation studies to find out if multielectrode stimulation is more effective as a communication aid than single-electrode stimulation, and to gain insights on stimulus coding of environmental sound using sophisticated digital signal processing techniques.

Audiometry↗