Recordings of Cortical Auditory Evoked Potentials in Cochlear Implant Listeners: A Preliminary Study / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: There is a need for fast and reliable objective measures of cochlear implant (CI) performance, especially in young children. The aim of the study was to investigate the detection and characterization of cortical auditory evoked potentials (CAEP) of different types of sound stimulation in CI listeners using a commercially available system, HEARLab™. SUBJECTS AND METHOD: Sound field CAEPs were obtained from 10 CI listeners, using three natural speech sounds (/m/, /g/, and /t/) presented at 55, 65, and 75 dB SPL. Detection rates, the latencies and amplitudes of CAEP waves were analyzed and compared with those of the normal hearing (NH) group. RESULTS: It was possible to detect CAEP responses in all CI listeners. Of the three stimuli (/m/, /g/, /t/), /g/ was the most robust waveform, although this was not statistically significant. Latencies for the /m/ stimulus were relatively longer than those for /t/ and especially for /g/, suggesting that CI listeners hear high-frequency sounds better than low-frequency sounds. When compared to the NH group, CAEP of CI listeners tended to show smaller amplitudes of various waves and longer latencies especially at P1 wave. CONCLUSION: CAEP responses could be obtained in all CI listeners and normal adults successfully, indicating that CAEP can be applied clinically as an objective assessment tool of hearing. Further studies are needed for CI listeners especially in infants and toddlers using this protocol to assess its clinical usefulness.

A Case of Squamous Cell Carcinoma in the External Auditory Canal Previously Treated for Verrucous Carcinoma

Carcinoma in the external auditory canal (EAC) is a rare malignancy with an annual incidence of one per one million people, accounting for less than 0.2% of all head and neck cancers. The most common histopathological type of EAC cancer is squamous cell carcinoma. Verrucous carcinoma is a well-differentiated, low-grade variant of squamous cell carcinoma. It is a locally destructive, invasive, and slow growing tumor that rarely metastasizes. Verrucous carcinoma occurs predominantly in the oral cavity and larynx, and its occurrence in the EAC is extremely rare. In this report, we present a histologically confirmed case of verrucous carcinoma in the EAC and temporal bone, which for several years had been classified as epithelial hyperplasia. Two-and-a-half years after diagnosis of verrucous carcinoma, a recurrent mass was found and the lesion was then confirmed to be squamous cell carcinoma.