Agreement between HRCT Imaging and Intraoperative Measurements in Predicting Stapedotomy Prosthesis Length in Otosclerosis Patients

Original Article Iranian Journal of Otorhinolaryngology, Vol.37(4), Serial No.141, Jul-2025 Agreement between HRCT Imaging and Intraoperative Measurements in Predicting Stapedotomy Prosthesis Length in Otosclerosis Patients Mohamad Reza Afzalzadeh1, Farzaneh Khoroushi2, Abolfazl Zanjani Tabasi1, Yazdan Gholami Chenaran3, Mohsen Rajati1, *Hassan Mehrad-Majd4 Abstract Introduction: This study aimed to evaluate the accuracy of preoperative high-resolution computed tomography (HRCT) imaging in measuring the distance from the long process of the incus to the footplate and its potential for predicting the optimal prosthesis length required for stapedotomy in patients with otosclerosis. Materials and Methods: This cross-sectional study included fifty patients scheduled for primary stapedotomy. A radiologist obtained and reconstructed preoperative HRCT scans of the temporal bone to measure the distance from the long process of the incus to the oval window in both axial and coronal views. These HRCT-derived measurements were then compared with intraoperative measurements performed by an otolaryngologist. The agreement between the two methods was assessed using correlation and BlandAltman analysis. Results: The mean distances measured by HRCT and intraoperatively were 4.15mm and 4.27mm, respectively. A strong and statistically significant correlation (r=0.928, P<0.001) was observed between the two approaches, indicating a robust association. The Bland-Altman analysis revealed a mean bias of 0.11±0.07mm, with limits of agreement (LoAs) ranging from -0.02 to 0.26 mm, and no points exceeding the 95% LoAs. The maximum potential error between the two measurement methods was 0.28mm, suggesting that HRCT imaging can reliably predict prosthesis length. In a stratified analysis based on the surgical distance (≤4 mm [N=11], 4.25mm [N=25], ≥4.5mm [N=13]), good agreement was maintained in the Bland-Altman analysis. Conclusion: Preoperative HRCT imaging may be a valuable tool for accurately predicting the required prosthesis length prior to stapedotomy in otosclerosis patients. Keywords: Otosclerosis, stapedotomy, incus bone, CT scan Received date: 05 Sep 2024 Accepted date:10 May 2025 *Please cite this article; Afzalzadeh MR, Khoroushi F, Zanjani Tabasi A, Gholami Chenaran Y, Mehrad-Majd H, Rajati M. Assessment of Agreement between HRCT Imaging and Intraoperative Measurements in Predicting Stapedotomy Prosthesis Length. Iran J Otorhinolaryngol. 2025:37(4):205-211. Doi: 10.22038/ijorl.2025.81759.3749 1Sinus and Surgical Endoscopic Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Iran. of Radiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. 3 Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 4Clinical Research Development Unit, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran. *Corresponding author: E-mail: 2Department Copyright©2025 Mashhad University of Medical Sciences. This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 International License https://creativecommons.org/licenses/by-nc/4.0/deed.en 205 Afzalzadeh MR, et al Introduction Otosclerosis is a significant cause of sensorineural hearing impairment, disproportionately affecting individuals of Caucasian descent. The condition typically begins with conductive hearing loss, which may progress to mixed hearing loss and, eventually, sensorineural hearing loss (1). Otosclerosis primarily impacts the otic capsule, where excessive osteoblastic activity leads to the deposition of spongy bone tissue, while osteoclastic activity destroys healthy bone tissue. This dual process ultimately leads to the fixation of the stapes, resulting in conductive hearing impairment. The most commonly affected structures include the oval window, anterior stapes, crura, footplate, and annular ligament. Conductive hearing loss occurs when the stapes, which normally transmit sound vibrations to the inner ear through the oval window, become fixed in place (2). This restriction in movement prevents the transfer of sound energy to the inner ear, leading to impaired sound conduction. Hearing loss is a defining characteristic of otosclerosis, often presenting as a gradual decline in bilateral hearing acuity. In many instances, this deterioration is accompanied by tinnitus, a condition characterized by ringing or other sounds in the ear. Physical examination findings may be limited. Diagnosing otosclerosis typically involves a comprehensive evaluation, combining audiometry with advanced imaging techniques, including high-resolution computed tomography (HRCT) of the temporal bone. This approach allows clinicians to accurately identify the condition while ruling out other potential causes of hearing loss. (3-8). Patients with otosclerosis can be treated through both medical and surgical interventions. Stapedotomy, or stapedotomy with a prosthesis, is the preferred treatment option; however, complications often arise due to inaccurate prosthesis length, which is a leading cause of stapedotomy revisions. Recent studies have shown that revision surgeries yield inferior outcomes, with success rates ranging from 16% to 80%. Each revision surgery results in a 10% reduction in the potential improvement in hearing. To improve the effectiveness of otosclerosis surgery, it is crucial to adhere to established surgical principles, which include ensuring appropriate indications for stapedotomy, conducting thorough preoperative evaluations using imaging techniques, and following the prescribed surgical protocols for otosclerosis procedures. Accurately measuring the prosthesis length is vital to the success of stapedotomy and revision surgeries. The correct prosthesis length is determined by the distance between the long process of the incus and the footplate, which serves as the standard for calculating the optimal prosthesis length. (9,10). Recent advances in high-resolution computed tomography (HRCT) have enabled the detection of features in the submillimeter range, significantly improving the accuracy of measurements between the long process of the incus and the footplate (11). Although there is ongoing debate regarding the necessity of performing HRCT imaging prior to stapedotomy, the current study aimed to evaluate the agreement between preoperative HRCT imaging and intraoperative measurements of the incus' long process and footplate in predicting the optimal prosthesis length for stapedotomy in otosclerosis patients. Materials and Methods This study recruited 50 individuals diagnosed with otosclerosis who were referred to the Otorhinolaryngology Clinics of two major hospitals (Ghaem and Imam Reza) in Mashhad, Iran, due to complaints of hearing loss. The diagnosis of otosclerosis was confirmed after a thorough assessment, physical examination, and hearing tests. The inclusion criteria were as follows: a visit t (...truncated)