Faculty Bibliography

A cerebellopontine angle epidermoid was identified in a noise-exposed patient as part of an occupational hearing conservation program. The patient is a 24-year-old employee of a major national newspaper who, because of workplace noise levels, was required to be part of a hearing conservation program. A shift in thresholds in 1 year was identified by the audiologic reviewer and referral for audiologic and otologic services was recommended and carried out. The steps leading from the initial air-conduction, pure-tone audiogram to final neurosurgical removal of the epidermoid CPA lesion was described. Such referral is essential if potentially health and life threatening conditions are to be identified and managed, although the primary objectives of the hearing conservation program remains the prevention of sensorineural hearing loss from workplace noise exposure.

The acoustic-reflex thresholds (ART) for multicomponent tonal complexes of varying bandwidth and spectral density were obtained from 20 normal-hearing (air-conduction thresholds less than or equal to 20 dB HL at 250-8000 Hz) young adults ranging in age from 20-30 years and 20 normal-hearing, old subjects ranging in age from 60-71 years. The results revealed that the ART decreased with spectral density, plateauing after seven components in the young group and after five components in the old group; the decrease in the acoustic-reflex threshold as a result of the increase in spectral density was less in the old than in the young group. The bandwidth effect (when bandwidth was plotted in hertz or octaves) on the acoustic-reflex threshold was present in the young adults, but substantially reduced in the elderly, as evidenced by the statistically significant interaction between subject group and signal bandwidth. The spectral density results are discussed in terms of their theoretic implications for the energy summation capacity and frequency resolution of the auditory system. The bandwidth results are discussed in terms of their theoretic implications for the frequency-resolving power of the auditory system.

The auditory brain stem responses (ABRs) to 500- and 2,000-Hz bone-conducted (BC) tones were recorded from 48 infants with ears exhibiting various external and middle ear states (normal, otitis media, auditory meatal atresia). Amplitudes were greater, wave V latencies longer, and detectability better for responses to 500-Hz BC tones compared to 2,000-Hz BC tones. Overall, most (94% to 100%) infants with normal cochlear sensitivity demonstrate ABRs to 20-dB normal hearing level (nHL) 500-Hz BC tones and 30-dB nHL 2,000-Hz BC tones. In cases in which masking is difficult (eg, bilateral atresia), infant ipsilateral/contralateral ABR asymmetries may help determine from which cochlea a response to the BC tones originates. In conclusion, two-channel ABR recordings to BC tones appear to be feasible for demonstrating normal cochlear sensitivity in infants.

Treatment of fistulae in children should be targeted at four different problem areas. The surgical intervention of these fistulae is most efficacious in controlling recurrent meningitis, which has not been discussed in this paper, and in the controlling of vestibular symptoms. Whether or not it will stop the progression of hearing loss or restore hearing is not known in a group of patients. It has been documented in this and other reports that the closure of the fistula will in specific cases appear to be associated in time with a stopping of the progression of the hearing loss and is associated also in time with the restoration of hearing function. Various factors must be considered in developing criteria for intervention. A decision to explore the ear should be based on history, audiometric change, vestibular testing including a fistula test, and malformation of bony labyrinth.

Thirty cases of congenital cholesteatomas of the cerebellopontine angle (CPA) treated over a period of 20 years are reviewed with regard to their clinical features, the pathophysiology of their symptoms, and their management. The predominant symptoms were related to cranial nerves VII and VIII and headaches. Signs and symptoms were divided into those caused by local involvement of the cholesteatoma, increased intracranial pressure, or both. Diagnostic procedures from invasive procedures such as ventriculography to more sophisticated noninvasive procedures including computed tomography and magnetic resonance imaging are discussed. The surgical management of 27 congenital cholesteatomas was accomplished via a posterior cranial fossa approach. Total excision of the cholesteatoma was the aim but was carried out in only five (18%) patients because of concern regarding the preservation of nearby neurovascular structures. Partial excision was possible in 22 (82%) patients. To minimize re-formation, the residual cholesteatoma was carefully cauterized with the aid of the operating microscope and bipolar diathermy without damaging surrounding neurovascular structures. Follow-up has ranged from 2 to 15 years, with four (13%) cases of re-formation.

The causes of nasopharyngeal obstruction are described. The diagnosis and treatment of each type of nasopharyngeal obstruction are presented in detail.