PROTOCOL OF CT-DESCRIPTION IN PREOPERATIVE PLANNING AND POSTOPERATIVE MONITORING OF COCHLEAR IMPLANTATION
Gridasova I.S.1,2, Korobkin A.S.2, Serova N.S.1
1 – Sechenov University.
2 – National Medical Research Center of Otorhinolaryngology, Federal Medical and Biological Agency. Moscow, Russia.
Purpose. To develop a protocol for computed tomography (CT) reporting in preoperative planning and postoperative monitoring of cochlear implantation.
Materials and Methods. A total of 150 patients (100%) aged from 8 months to 16 years (83 males, n=83, 55.3%; 67 females, n=67, 44.7%) with a diagnosis of grade 4 sensorineural hearing loss were examined at the National Medical Research Center for Otorhinolaryngology, FMBA of Russia for preoperative cochlear implantation planning. All patients underwent high-resolution CT of the temporal bones at both the pre- and postoperative stages. During the study, a detailed protocol was developed that includes a comprehensive description of all anatomical structures and parameters critical for surgical planning and implant placement, as well as for postoperative device monitoring.
Results and discussion. All patients (n=150; 100%) underwent cochlear implantation based on preoperative planning, followed by postoperative CT monitoring of electrode array position using the developed description protocol. Preoperative CT revealed anatomical variations of the temporal bone in 26% of cases (n=39) and inner ear malformations in 10,7% (n=16), enabling safe surgical access planning in each individual case. Measurement of the cochlear duct length (ranging from 11,8 to 36,7 mm) ensured individualized electrode selection, while CT-detected ossification in 8% of patients (n=12) determined the surgical implantation strategy. Cochlear implantation was performed in all patients, with a trans-membranous approach in 86% of cases (n=129) and via cochleostomy in 14% (n=21). Postoperative CT demonstrated that the distal electrode tip was predominantly located in the middle (n=112; 74,6%) and apical (n=83; 55,3%) turns of the cochlea, confirming the efficacy of preoperative planning. CT enables detailed visualization of all temporal bone structures, providing accurate characterization of anatomical variants and developmental anomalies in preoperative planning. The most critical parameters for cochlear implantation planning were cochlear duct length, patency, and access to the round window. Additionally, the cochlear orientation angle (α) was assessed in our study, with a mean value of 56,8°, which is consistent with previously reported data (54,6-56.1°). It was established that α < 50° is associated with difficult round window visualization and technical challenges in accessing it, whereas larger values facilitate the surgical procedure. The mean dimensions of the round window (1,5 mm) and its bony overhang (height 1,46 mm, thickness 0,83 mm) further underscore the importance of preoperative CT assessment.
Conclusion. The developed protocol for describing CT scans allows to optimizing the assessment of the temporal bones during preoperative planning and postoperative monitoring of cochlear implantation, which increases the effectiveness of treatment strategies for this category of patients..
Keywords: computed tomography, cochlear implantation, cochlear duct length, tympanotomy.
Corresponding author: Gridasova I.S., e-mail: Этот e-mail адрес защищен от спам-ботов, для его просмотра у Вас должен быть включен Javascript .
For citation: Gridasova I.S., Korobkin A.S., Serova N.S. Protocol of CT-description in preoperative planning and postoperative monitoring of cochlear implantation. REJR 2026; 16(2):21-31. DOI: 10.21569/2222-7415-2026-16-2-21-31.
Received: 21.04.26 Accepted: 01.08.26