Original Research Article
Year: 2018 | Month: March | Volume: 5 | Issue: 3 | Pages: 87-92
Retrospective Clinico-Radiological Correlation of Stapes Footplate Thickness in Cases of Otosclerosis Undergoing Small Fenestra Stapedotomy and Stapes Prosthesis Insertion: An Indian Perspective
Manoj Kumar Kanzhuly1, Salil Kumar Gupta2, U Rajesh3, Rakesh Datta4, Renu Rajguru4, Anubhav Singh5
1Asisstant Professor, 2Senior Resident, 4Professor, 5Junior Resident,
Department of ENT & HNS, Armed Forces Medical College, Pune, Maharashtra, India
3Asisstant Professor, Department of Radio-diagnosis, Armed Forces Medical College, Pune, Maharashtra, India
Corresponding Author: Salil Kumar Gupta
ABSTRACT
Introduction - Small fenestra stapedotomy has now become a standard of care with minimal complications for successful treatment of stapedial otosclerosis. Definitive diagnosis of otosclerosis can only be made intraoperative inspection and confirmation of fixation of stapes foot plate. However, preoperative evaluation of stapes foot plate thickness by high resolution computed tomography (HRCT) scan of temporal bone can be done with high specificity and sensitivity. But there appears to be a discrepancy in stapes foot plate thickness as measured on HRCT temporal bone and what is found intraoperatively.
Methods - 80 ears diagnosed with otosclerosis and scheduled for small fenestra stapedotomy from January 2015 to December 2017 were taken in study as per inclusion and exclusion criteria of study. Preoperative HRCT temporal bone was done and Stapes foot plate thickness (SFTi) was calculated. Intraoperatively distance between medial surface of long process of incus to stapes footplate (L) and hence Ideal piston length was calculated. After making fenestra, actual piston length (APL) needed was recorded and actual stapes foot plate thickness (SFTo) was calculated. Comparison was made between measurement of stapes foot plate thickness preoperatively on HRCT temporal bone (SFTi) and intraoperatively (SFTo).
Results - Analysis of data revealed - Mean SFTi - 0.83 mm ranging from 0.5 – 1 mm, Mean L - 2.8 mm ranging from 2.2 – 3.6 mm. Mean IPL - 3.9 mm ranging from 3.25 – 4.75 mm, Mean APL - 4.06 mm ranging from 3 to 4.8 mm. Hence, Mean SFTo is calculated to be 1.04 mm ranging from 0.55 – 1.85 mm. With taking 95% confidence interval the difference between SFTi and SFTo ranged from -0.2629 to -0.0746. By taking standard error of difference as 0.047, two tailed P value is calculated as 0.0006 which was statistically extremely significant.
Conclusion - Preoperative HRCT evaluation of stapes footplate thickness benefits the patient as well as surgeon in view of decreased surgical time, selection of appropriate instruments and equipments and prevention of complications. However discrepancy in measurement of stapes foot plate thickness on HRCT and intraoperatively defeats the purpose and expose a lack of a definitive and well designed HRCT protocol to measure thickness of posterior part of stapes foot plate thickness which is invaluable for a successful surgery. Therefore, a felt need have risen to develop strict HRCT protocols taking into consideration the specific bony landmarks to measure stapes foot plate thickness, especially the posterior part, where stapedotomy is performed.
Key words: Stapedial otosclerosis, Small fenestra stapedotomy, High resolution computed tomography (HRCT) scan temporal bone, Stapes foot plate thickness.
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