A Study on the Effect of Stapedotomy on Carhart Notch in Patients with Otosclerosis

Carhart Notch (CN) is considered a hallmark of otosclerosis, characterized by a dip in the bone-conduction (BC) at nearly 2 kHz on pure tone audiometry (PTA). The notch reversal may be achieved post-operatively by surgical intervention and mobilization of the stapes. To assess the preoperative pattern of BC threshold responses and to analyze the effect of stapedotomy on CN. A prospective interventional clinical study was undertaken comprising 50 patients admitted with otosclerosis, with CN on pre-operative PTA and air-bone gap (ABG) on the PTA of a minimum 15 dB. Detailed history was recorded from all patients, followed by complete ear, nose and throat examination, blood investigations, PTA and impedance audiometry. Chi square /Fisher test and Wilcoxon signed rank test were used to find the association and compare the median of the pre- and post-surgical change in PTA. P value of <0.05 was judged statistically significant. A significant improvement was noted post-surgery, reducing both average ABG (31.12 dB vs. 55.44 dB; P=0.000) and average air conduction on PTA (9.53 dB vs. 43 dB; P=0.000) compared to pre-surgery. Most patients (40/50) did not have CN post-operatively. A Carhart Notch is most predominant at 2 kHz in patients with otosclerosis. CN disappeared in most patients with the closure of air conduction and ABG, post-stapedotomy. Hence, stapedotomy is an effective surgery in the treatment of otosclerosis with a low risk for complications.