ASSESSMENT OF THE IMPROVEMENT OF CARHART'S NOTCH FOLLOWING STAPES SURGERY IN PATIENTS WITH OTOSCLEROSIS

Carhart's Notch (CN) is a major audiometric criterion for diagnosis of otosclerosis; it is an abnormal audiometric pattern due to fixation of stapes and relative reduction in perilymphatic motion. 130 patients (146 diseased ears) were evaluated in this study. Audiometric tests were performed for each patient 2 weeks before and 6 month after surgery, and the average decline in bone conduction threshold was measured in frequencies of 500, 1000, 2000, and 4000 Hz. The average correction in CN in frequencies of 500, 1000, 2000, and 4000 Hz was 3, 5.4, 10.4 and 3 db, respectively after stapedectomy, and 4, 5.8, 9.6 and 4.2 db, respectively after stapedotomy. Mean correction of CN in the above frequencies was 3.8, 5.7, 9.8 and 3.8 db, respectively, measuring 5.7 db on the average. There was a significant correlation between CN correction and stapes surgery. The highest correction was seen in 200 Hz (9.8 db) and the lowest in 500 Hz (3.8 db). The correlation between the type of surgery and specific changes in CN was not significant.