The Best-Matched Pure Tone Average and Speech Recognition Threshold for Different Audiometric Configurations / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The agreement between pure-tone average (PTA) and speech recognition threshold (SRT) has become more important with the increasing demands for medical certification. The purpose of this study was to explore the relationships between the SRT and several variations of PTA, and to determine which PTA formula would provide the best agreement with SRT for different audiometric configurations. SUBJECTS AND METHOD: Audiological data on 783 ears were retrospectively collected. The air-conduction PTAs were calculated using five different formulas: three-frequency average (3FA), weighted three-frequency average (W3FA), four-frequency average (4FA), weighted four-frequency average (W4FA), and six-frequency average (6FA). The audiometric configuration was classified into five categories. The PTA-SRT relationships were analyzed using correlation and simple linear regression for each audiometric configuration. RESULTS: Highest correlation was observed between the SRT and W3FA for all audiometric configurations with the correlation coefficient of 0.964 as a whole. The SRT and 3FA were best-matched in the linear regression models for overall/flat/high frequency gently sloping/low frequency ascending; the SRT and W3FA were best-matched for high frequency steeply sloping (HFSS); the SRT and 4FA were best-matched for miscellaneous audiograms. CONCLUSION: The most stable PTA variations that make the best-matched pairs with SRT for any audiogram are the conventional 3FA and W3FA doubling 1 kHz threshold. The addition of frequencies higher than 2 kHz to a PTA formula seems to have impeded the PTA-SRT agreement, especially for HFSS audiograms. W3FA should be the method of choice in predicting SRT from PTA for HFSS audiograms.

A Case of Primary Papillary Thyroid Cancer That Caused Vocal Cord Palsy Arising from Thyroid Rest

Thyroid rest is isolated deposit of normal thyroid tissue arising in the thyrothymic tract below the lower pole of thyroid gland. Malignant transformation of thyroid rest is very rare. We report an extremely rare case of papillary carcinoma arising from thyroid rest in a 56-year-old male. He presented with hoarseness due to vocal cord palsy. Paratracheal mass in the upper mediastinum was identified by the cause of vocal cord palsy on CT. During surgery, we identified that the mass invaded recurrent laryngeal nerve but had no connection to thyroid gland. Histopathologic examination revealed that the mass was primary papillary thyroid carcinoma and there was no evidence of malignancy in thyroid gland. The post-therapeutic I-131 whole body scan detected several focal hot uptake in lung and mediastinum, suggesting distant metastasis. We should have knowledge of developmental variations of thyroid gland such as thyroid rest and its malignant transformation.