Reporting guideline: STROBE
A retrospective review was done for mastoidectomies performed between
July 2011 and July 2018 by 2 senior surgeons were identified via the
electronic surgical logbook. Patients with primary cholesteatomas were
included, excluding congenital cholesteatomas and incomplete data. Data
extracted comprised preoperative demographics, high-resolution CT (HRCT)
0.5mm thickness temporal bone scan results, intraoperative findings and
hearing results.
Diagnostic accuracy and correlations of non-contrast HRCT scans with
intraoperative findings were analysed for 1) erosion of structures:
ossicular chain, tegmen tympani, tympanic facial canal and semicircular
canal, 2) location of squames and 3) ossicular chain encasement. The
technique of matrix preservation or removal was dependent on surgeon
choice and intraoperative findings, such as presence of intact
endosteum. Material to repair LFs was also noted. Average air conduction
(AC), bone conduction (BC) and air-bone gap (ABG) pure tone threshold
(PTA) were performed at 500Hz, 1kHz and 2kHz for all patients pre- and
post-operatively. A change of BC PTA of 10dB or more is considered
clinically significant.
Statistical analysis was conducted using chi square test using IBM SPSS
statistic package, version 25. Cholesteatomas were categorized into
“LF” and “No LF” groups. Continuous variables such as age and
hearing levels were reported as mean (standard deviation, range).
Comparisons of categorical variables were performed using the Pearson
chi-squared test.