Presentation schedule is subject to change. For the most up-to-date information, visit www.entannualmeeting.org. Objectives: Although most of the laryngeal leukoplakias are temporal inflammatory lesions in non-smokers, some patients represent serious histopathologies to require careful management. The purpose of this study was to clarify unique clinical features of the patients who require cautious care in this lowrisk group.Methods: One hundred fifty-four consecutive patients referred to our institution with laryngeal leukoplakia from June 2006 to May 2013. Of these, 24 patients without smoking history were incorporated in this study. Retrospective chart reviews and the re-evaluations of video-taped laryngeal images were performed. Sequential change of vocal quality (Grade, Roughness, Breathiness, Asthenia, Strain scale) was assessed in each patient. Timings to show improvements of laryngeal images were studied in the patients with spontaneous disappearances of leukoplakias (n = 12). Furthermore, excisional biopsies were performed on 12 patients and their histopathologies and vocal/stroboscopic characteristics were compared with each other.Results: Spontaneous disappearances of the lesions were observed 4.6 months after referral to our hospital on average, and these patients presented vocal quality of G1 or G0 at their first visits. Additionally, gradual recoveries in their glottal closure and/or pliability of diseased vocal folds were observed in this group. Furthermore, patients with histopathology of severe dysplasia/cancer presented with either (1) no improvement in their G2 voice for 1 month, (2) incomplete glottal closure coupled with abnormal pliability of diseased vocal folds for 1 month, or (3) abnormal pliability of diseased vocal folds for 4 months.Conclusions: Our analyses identified several specific findings to predict serious pathology in laryngeal leukoplakia patients without smoking history.

P229Results: Varying degrees of EH were observed in 14 of the 16 ears. Episodes of acute sensorineural hearing loss or vertigo occurred in 4 ears with severe EH in the cochlea and 3 ears with severe EH in the vestibules. Overall, 12 of 14 ears with EH did not undergo stapes surgery. Ears without EH showed no postoperative complications, but one ear with mild EH in the vestibule showed severe vertigo following the surgery. Conclusions:The presence of EH in cases with otosclerosis was clearly visualized, and the degree of EH was correlated with the clinical findings in most patients. Such preoperative MRI evaluation could provide useful information to prevent complications following stapes surgery.