otitis media is defined as an inflammatory disease of the middle ear that may be infectious or not and focal or generalized . the course of disease may be acute with a tendency towards total resolution and a return to the integrity of the regions affected , or it may be chronic with permanent sequelae1 
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 3 . chronic otitis media ( com ) is clinically characterized as an inflammatory condition associated with otorrhea and tympanic membrane perforation in some cases . the disease course is more than 3 months in duration and histopathologically it is associated with irreversible tissue changes . the incidence of com is higher in less developed countries . malnutrition , poor hygiene , poor quality housing , and high population density are factors that are associated with a higher incidence of middle ear infections3 
 4 . com can be subdivided into two groups : cholesteatomatous chronic otitis media ( ccom ) and chronic otitis media without cholesteatoma ( comwc ) . cholesteatoma may be classified as congenital or acquired , and is further categorized as primary or secondary cholesteatoma . the surgical approach is suitable for both ccom and comwc and encompasses tympanoplasty , canal wall - up ( cwu ) and canal wall - down ( cwd ) mastoidectomy1 
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 6 and its variations , including modified radical mastoidectomy or bondy 's procedure . the choice of technique remains controversial and is usually decided based on the presence or absence of cholesteatoma , its location , the state of the middle ear mucosa , and auditory thresholds . recurrence and post - operative functional status vary between techniques . the aim of this study was to clarify which surgical technique provides the best outcomes in terms of disease control and improved hearing thresholds . the medical records of patients with com who underwent a cwu or cwd mastoidectomy at the otorhinolaryngology department of a tertiary hospital between 1997 and 2005 were evaluated . postoperative outcomes for the 2 techniques mentioned above were compared using control of the disease , absence of otorrhea , and cholesteatoma recurrence during the follow - up period , which was at least 24 months , as criteria . pure tone average hearing thresholds at 500  hz , 1000  hz , and 2000  hz were also compared before and after surgery for both techniques . statistical analyses were performed using the chi square test , and p values < 0.05 were considered statistically significant . inclusion criteria : patients of both sexes who were over 14 years of age , diagnosed with com , had undergone a cwu or cwd mastoidectomy with preoperative and postoperative audiometry , and who were followed up for at least 2 years . exclusion criteria : patients with sensorineural hearing loss , exposure to occupational noise , previous ear surgery , history of head trauma , or with a suspected perilymphatic fistula were excluded . the study was approved by the ethics in research committee ( number : 098/07 ) . a total of 88 patients ( 33 men and 55 women ) were selected for the study . their average age was 30 years ( standard deviation , 15.17 ) with a minimum age of 14 and a maximum age of 78 . the average period of postoperative follow up of these patients was 7.5 years . in the group of 39 patients with ccom , 20 ( 51.3% ) three ( 15% ) of these patients required a second surgery due to persistent otorrhea . of the 19 ( 48.7% ) patients who underwent a cwu mastoidectomy , 11 ( 57.9% ) required a further operation , 8 due to the recurrence of a cholesteatoma and 3 due to persistent otorrhea . of the 49 individuals with comwc , 8 ( 16.6% ) underwent a cwd mastoidectomy , and 2 ( 25% ) of these required a further operation due to persistent otorrhea . of the 41 ( 84.4% ) patients who underwent a cwu mastoidectomy , 5 ( 12.2% ) required further surgery , including 4 for persistent otorrhea and 1 due to the evolution of cholesteatoma . when the cwu and cwd techniques were compared among the patients with ccom , a higher rate of disease control and the absence of otorrhea and cholesteatoma were associated with the cwd technique ( p  <  0.05 ) . there were no statistically significant pre- or postoperative differences in the pure tone average thresholds at 500  hz , 1000  hz , and 2000  hz between the techniques . among the patients with comwc , the disease control rate was 91.9% , regardless of the technique used , which is similar to the rates reported in other studies , which have ranged from 63% to 96%7 
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 10 . among the patients with ccom , the disease control rate was 64.1% , which is slightly lower than previous reports , which have ranged from 75% to 90%7 
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 13 . when the cwu technique was used , the disease control rate for the first surgery was 76.6% . in contrast , when the cwd technique was used , the disease control rate was 85.7% , regardless of the presence of cholesteatoma . data in the literature are similar with reported values ranging from 71% to 95% for the cwu technique9 
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 16 and from 71% to 96% for the cwd technique9 
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 16 . in the comwc group , a higher rate of revision surgery was found among patients who underwent a cwd mastoidectomy ( 25% ) compared with a cwu mastoidectomy ( 12.2% ) . this can be explained by the fact that patients with more severe disease were selected for cwd mastoidectomy . of the patients with ccom who underwent a cwu mastoidectomy , 57.9% required revision surgery whereas only 15% of those who underwent a cwd mastoidectomy required revision surgery . the current literature also shows higher recurrence rates when patients with cholesteatoma undergo a cwu mastoidectomy . cruz et al . ( 2001 ) reported surgical revision rates of 37.5% and 26.08% when using the cwu and cwd techniques , respectively . we believe that in our study the higher rate of reoperation observed when preserving the canal wall is related to the longer follow - up ( median 7.5 years ) , and suggests late complications of the disease , which are not uncommon when the cwu technique is used . the choice of technique remains controversial but this study , in agreement with the literature , has shown that cholesteatoma can be treated with the cwu technique . however , bento et al . and cruz et al.14 
 5 suggest that criteria such as cholesteatoma restricted to the attic , good condition of the middle ear mucosa , and the possibility of good postoperative follow - up are required before the cwu technique is used . in this study , no statistically significant difference in pure tone average thresholds before and after surgery with either of the techniques . because patients with less than 2 years follow - up were excluded from the study , there was a considerable decrease in the number of individuals available for analysis , which hindered any robust analysis of this variable . in the literature we found many studies that reported better audiometric results when the cwu technique was used rather than the cwd technique7 
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 17 . however , other studies have reported no significant differences in hearing outcomes in association with the two techniques16 . the cwd technique and its various modifications results in better outcomes , especially when it comes to surgery to control ccom . some precautions facilitate a satisfactory functional outcome with better control of persistent otorrhea and greater certainty as to the eradication of cholesteatoma compared to cwu mastoidectomy . ccom - cholesteatomatous chronic otitis media ; comwc chronic otitis media without cholesteatoma ; rr  relative risk ; 95% ci - 95% confidence interval ; p value from the chi - square test < 0.05 .
summary 
 introduction :  chronic otitis media ( com ) is an inflammatory condition associated with otorrhea as well as large and persistent perforations of the tympanic membrane in some cases . 
 com can also lead to cholesteatoma . 
 surgical treatment with canal wall - down and canal wall - up tympanomastoidectomy is considered for both types of illness . 
 the choice of technique is controversial and is dependent on several factors , including the extent of disease . 
 objective :  we aimed to evaluate surgical outcomes in com patients with and without cholesteatoma treated with canal wall - down and canal wall - up tympanomastoidectomy . 
 disease eradication and post - operative auditory thresholds were assessed . 
 method :  patient records from the otorhinolaryngology department of a tertiary hospital were assessed retrospectively . 
 results :  patients who underwent canal wall - up tympanomastoidectomy had a higher rate of revision surgery , especially those with cholesteatoma . 
 however , there were no statistically significant differences in post - operative hearing thresholds between the two techniques . 
 conclusion :  the canal wall - down technique is superior to the canal wall - up technique , especially for patients with cholesteatoma .