Objective: To evaluate the add value of combined analysis of high resolution computed tomography (HRCT) temporal bone parameters in accurate prediction of round window (RW) visibility through posterior tympanotomy.
Patients and methods: a retrospective observational study was held in a tertiary center, conducted on 45 cochlear implant pediatric candidates between January 2017 and September 2019. Candidates were referred for CT temporal bone. They were classified into fully visible RW cases and partially or non-visible RW cases. Radiological measurements were compared between the two groups for prediction of RW visibility separate and in combination.
Results: 45 patients were included in the study (26 males (57.8%) and 19 females (42.2%)). Their median age was 4 years (2-12 years). There were 38 (84.4%) fully visible and 7 (15.6%) partially or non-visible RW cases. Kashio posterior line (n:32/3), fascial recess width (FRW) (mean: 4.9 (3.5-7.5)/4.2 (4-4.7) mm) and round window location (RWL) (3 (1-4)/2.8 (1-3)mm) measurements significantly differentiated between the two groups; (P value 0.034, 0.012 & 0.025 respectively). Posterior kashio line and cut off values of ≥4.75 mm of FRW & 2.95 mm of RWL were showed sensitivity 84.2%, 63.2% & 65.8%, and accuracy 80%, 68.9% &68.9% in prediction of RW visibility respectively. Combination of Kashio prediction line with cut off value ≥ 7.45 mm (sum of FRW & RWL) showed P value 0.003 with further improve in the sensitivity and overall accuracy in prediction of RW visibility from 84.2% to 80% up to 91.4% and 88.6% respectively.
Conclusion: combined parameters using Kashio line with FRW and RWL increases sensitivity and overall accuracy in prediction of RW visibility rather than single parameter.
Keywords: Cochlear implant; Computed tomography; HRCT; Round window.
Copyright © 2020. Published by Elsevier B.V.