Study of Hearing Status After Canal Wall Down Mastoidectomy with Type-III Tympanoplasty

Objective: To observe hearing status in case of canal wall down mastoidectomy with type III tympanoplasty. Methods: This was a cross sectional study which was carried out in the departments of Otolaryngology and Head-Neck surgery of Bangabondhu Sheikh Mujib Medical University during the period of July’ 2011 to March’ 2012.A Total 38 patients having cholesteatoma underwent canal down mastoidectomy with type III tympanoplasty,were included in this study. Patients were divided into two groups according to their age. Age belonged to 18 years and more than 18 years were considered as child and adult respectively. Patients were examined thoroughly and preoperative hearing level was assessed by pure tone audiometry one one week before operation. Post operative patients were followed up at regular intervals. Pure tone audiogram (PTA) was done after 8 weeks and hearing assessment was compared by closure of air bone gap. Results: In this study majority of patients were within 13-17 years in child group and 1835years in adult group. Most of patients were male.Closure of air-bone gap was significantly higher in adults. Improvement of hearing status was more in adults. Conclusion: CWD mastoidectomy with tympanoplasty not only lowers recurrence rate but also improves hearing status although less likely in child and younger age group than adults.


Introduction:
Canal wall down mastoidectomy with tympanoplasty (CWDT) for chronic suppurative otitis media with atticoantral variety is a common otological surgery. The aims of surgery are removal of the disease and preservation of good hearing function. Our aim is to report the hearing outcome of patients with CSOM with atticoantral variety, who had mastoidectomy with the classical Wullstein type III tympanoplasty.
Chronic SuppurativeOtits Media (CSOM) is a stage of ear disease in which there is chronic infection in the middle ear cleft. 1 It is a disease of insidious onset and present with persistent aural discharge and hearing impairment as a result of repeated infection from nose nasopharynx& oropharynx or from persistent Eustachian tube dysfunction or from improper treatment of ASOM. 2 Chronic Suppurative Otits Media is a worldwide health problem but higher in developing countries. Poor living conditions, poor hygiene, malnutrition, lack of access of medical care-all are major risks for CSOM. Young age, genetic factors, bottle feeding, use of a dummy, day care attendance, passive smoking are also contributing factors. 3,4 The prevalence of CSOM in Bangladesh is 4.5%according to WHO situation review report. 5 The prevalence rate of CSOM in two different studies in our country in slum area and in rural area among children are found to be 7.39% and 12.44%respectively-are alarming for us. 6 CSOM is classified based on the location of perforation and presence of pathologies like cholesteatoma and retraction pockets. When there is central perforation in the pars tensa it is called tubotympanic variety of CSOM, on the other hand when there is marginal perforation or presence of either a cholesteatoma or a retraction pocket, then it is called atticoantral variety. Among these variety attico-antral or unsafe varietyis more concerning to otologists. Because the most fascinating topics and one of the greatest and most complex problems in otology, Cholesteatoma is related with these variety. In clinical practice up to 50% of ears with active chronic otitis media is associated with cholesteatoma among 5% CSOM prevalence rate in our country. 7 The choice of treatment of cholesteatoma is surgery for which the ideal goal is the total clearance of disease to obtain a safe, dry ear, and restoration or maintaining the functional capacity within a one stage surgical procedure if possible. 8 Children are considered to be less successful than in adults because of repeated RTI,poorer tubal function and higher incidence of otitis media. 9 There are different surgical modalities for management of CSOM with cholesteatoma: intact canal wall procedures or closed mastoidectomy (combined approach tympanoplasty), canal wall down mastoidectomy (atticoantrosomy, radicalmastoidectomy, Modified radical mastoidectomy). 10 Former is associated with higher recurrence rate (5% to 71%) but preservation of hearing is maintained .In canal wall down procedure there is less rcurrance rate but with loss of hearing.With the concept of modern reconstructive surgery Tympanoplasty which is done by zollner&wullsteen (1953,1956) of Germany, made revolution in tympanomastoid surgery (canal wall down mastoidectomy with tympanoplasty)where almost disease clearance is achieved along with reconstruction of middle ear sound system done for hearing improvement. In type III, only stapes suprastructure present and placement of allograft is done on top of the stapes capitulum. Now a day's canal wall down mastoidectomy with type III tympanoplasty under magnification is advocated by most otologists.The study is expected to show the hearing improvement after canal wall down mastoidectomy with tympanoplasty type-III.

Selection criteria:
A.Inclusion criteria: • All patient of CSOM with cholesteatoma • Patient more than 5 years & below 50 years.
• Those who will give informed consent to undergo the study.
• CSOM with External & Inner Ear abnormality, SNHL or any systemic disease.
Sampling technique:Purposive sampling technique was adopted. All the available subjects during the data collection period who fulfilled the study selection criteria were included in the study.

Data collection technique:
Complete history taking and clinical examination were doneand recorded in data collection sheet. Preoperative hearing level was assessed by pure tone audiometry and impedance audiometry one week before operation. Both group of patient were operated on under general anaesthesia with post auricular approach. Temporalis fascia was taken as graft material and placed over the stapes head after doing modified radical mastoidectomy. Operation was done by various surgeons. Post operative patients were followed up at weekly interval for the first month and then 02 weekly intervals up to 08 weeks and after that pure tone audiogram (PTA) was done and compared hearing assesment by closure of air bone gap.

Data analysis:
After collection all the data were checked and edited. Then data were entered into computer with the help of software SPSS 16 version. Among the study subjects more than one third was in 18 to 35 years age group (34.21%). Less than one third was in 13 to 17 years age group (26.31%)

Observation and Results
Among the study subjects more than two thirds was male (73.68%) and less than one third was female (26.32%).
More than half of the patients had attic perforation (60.52%). More than one third had marginal perforation (39.48%). The graft accepted in 78.94% cases. Graft accepted rate is more in adults.     Improvement of post operative hearing status was more in adults(80%) than in child(50%).

Discussion:
In this cross sectional study all patients were underwent CWD mastoidectomy with type III tympanoplasty for CSOM with cholesteatoma and observed the pre and post operative hearing results in terms of average ABG and the size of ABG closure in adults and child separately.
In this study average age of the patients was 24.22 years being range from 8 to 50 years and which was almost similar to another study (mean age 21.3 years). 11 Most of patients belonged to the age group 11 to 20 years which is similar to other study. 12  In this study adults had more improvement in gaining hearing status as well as dry mastoid cavity and better acceptance of graft taking whereas children had overall mild improvement in hearing gain and had more discharging mastoid cavity with more graft failure although the surgical procedures were same in both groups.
Main reasons behind such findings are due to having more extensive disease process due to well pneumatization of mastoid bone, horizontally placed Eustachian tube are prone to get middle ear infection, medialization of grafts and being poor follow up responder.

Conclusion:
Management of chronic suppurative otitis media with cholesteatoma should be aimed to prevent complication and recurrence rate and also improvement of hearing status. The functional results of this study support the importance of type III typmpanoplasty in conjunction with canal wall down mastoidectomy (CWD). In fact CWD mastoidectomy with tympanoplasty not only lowers recurrence rate but also improves hearing status although less likely in child and younger age group than adults because of pneumatization of mastoid, eustatian tube dysfunction and poor follow up respond.