Stapedotomy and its effect on hearing – our experience with 54 cases.

. Introduction: This study reviews the cases of stapedotomy and evaluates its effectiveness at improving hearing loss in patients with otosclerosis. Results: A total of 54 stapedotomy surgeries (52 unilateral and 1 bilateral surgeries) were received. Average post-operative ABG for 0.5, 1, 2 and 4 KHz showed that 61.1% had complete closure of ABG ( ABG < 10 dB) compared with 1.6% preoperatively and 85.2% had closure of ABG to within 20dB compared with 4.7% preoperatively (t – 13.89, p = 0.000). More than 94% had hearing improvement and 81.5% had ABG closure greater than 10 dB postoperatively (mean gain 23.38 ± 12.37, t = 13.89, p = 0.000). A total of 13% complications were recorded with TM perforation (5.6%) being the commonest complication. Conclusion: Stapedotomy is an effective surgical procedure for the treatment of otosclerosis which leads to improvement in patients’ quality of life. A favorable hearing outcome can be obtained by the combination of experienced hands with minimal surgical trauma and appropriate surgical technique.


Introduction
Otosclerosis is a disease that causes progressive hearing loss due to fixation of stapes by abnormal bony depos-it1.This leads to impairment of the normal conducting mechanism of the sound conducting system in the middle ear 1 .Complete understanding of what causes otosclerosis is not known yet but published studies however showed that it is a genetically transmitted disease which is usually inherited in an autosomal dominant pattern with variable penetrance 2,3 .Other factors linked to otosclerosis include autoimmune and viral infections 4-6.A recent systematic review however concluded that more evidence is necessary to link otosclerosis and autoimmunity 7,8 .
Otosclerosis occurs in about 10% of the Caucasian population [1][2][3] ; it is less common in the Japanese and South American descent and rare in the Afro-American population 1,8 .In about 60% of the affected patients, family members also have otosclerosis [4][5][6] .The disease occurs twice as much in women than men [1][2][3][4] and pregnancy has been reported to contribute to worsening of the symptoms in the affected patient 8 .The most common symptom is a slow progressive hearing loss that presents from age 20 to 45 years 9 .
Otosclerosis can occur in both ears in about 80% of patients.The severity of the hearing loss is variable, but total deafness is rare.If the disease involves the otic capsule, a sensorineural hearing loss can occur 9,10 .Other symptoms of otosclerosis include tinnitus and dizziness and these symptoms can improve with surgical intervention in a number of cases [9][10][11][12] .
Diagnosis is usually made by a combination of history of progressive hearing loss and audiometric evaluation 13,14 .Pure tone audiometric test shows the typical conductive hearing loss pattern.Impedance audiometry often shows stiffening of the ossicular chain and acoustic reflexes may be absent.Computerised tomographic scan of the temporal bone is specific but insensitive 12 .Various treatment modalities for otosclerosis have been described 1,10,12,13 .This includes watchful waiting, medical, hormonal (avoidance of estrogens or use of estrogen blockers), hearing aids and surgical 1,10,12,13 .Surgery in the form of partial (stapedotomy) or complete (stapedectomy) removal of the fixed stapes and replacement with a prosthetic device (implant) has produced excellent hearing results that remain good for many years and proved to be effective in improving associated tinnitus in the affected patients [14][15][16][17][18] .This surgery that was initially described by Shea 19 had made remarkable advances in both the technique and implant materials which have contributed to improvement in surgical outcome 17,18,20 .The aims of this study were to review all the cases of otosclerosis that were managed by stapedotomy over a year period and evaluate the hearing outcome in the affected patients.It also compares the hearing outcome with the findings from other published studies.

Materials and method
Medical records of all the cases of stapedotomy done from January 2012 to December 2012 at Indorewala ENT Hospital, DNB Institution and Research, Nashik, India were retrospectively reviewed.Data was obtained from the records of the patients that had minimum follow up after surgery of at least 6 months.Information retrieved by the investigator from the record included; socio-demographics, side of the ear affected, type of prosthesis used and pre and postoperative pure tone audiogram for hearing outcome and associated surgical complication(s).Diagnosis of otosclerosis was based on the history, medical status with otomicroscopy, Rinne and webber test, impedance audiometry with tympanogram and stapedius reflex test.All the patients reviewed had pure-tone audiograms pre-operatively and post-operatively.The PTA was performed using the Elkon 3N3 multi, by Elkon India, calibrated yearly to ISO standard in a sound-proof room.We compiled data on the pre-and post-operative air -bone gap (ABG) at 0.5, 1, 2 and 4 KHz.The mean thresholds of the above-mentioned data were determined at 0.5, 1, 2, and 4 kHz.The ABG was calculated using air conduction (AC) and bone conduction (BC) thresholds recorded on the same audiogram.Postoperative hearing gain was then calculated from the ABG before the operation minus the ABG of the last follow-up examination (minimum of 3 months after surgery when all the healing processes had been adjudged completed and the patient was clinically stable).Patients whose audiometric data was insufficient or who were lost to follow-up were excludedfrom the study.
All surgical procedures were performed via endomeatal approach under local anaesthesia; local blockage of the ear with 1% lidocaine in 1:30 000 adrenaline.A posterior tympanomeatal flap (posterior tympanotomy) was incised and raised.The posterior tympanic bone (bony overhang) was then drilled to permit full visualization of the oval window while corda is usually preserved.The stapes was then inspected and palpated to confirm the diagnosis of otosclerosis.The lateral ossicular chain was also palpated to verify its mobility Posterior and anterior crura were weakened by drill.Mid footplate area demucosified and mid footplate 0.7 mm fenestration drilled.The distance between the oval window and the long process of the incus was then measured, and appropriate size prosthesis inserted.Following prosthesis insertion, stapes superstructure was removed by separating the incudostapedial joint and cutting the stapedial tendon, the mobility of chain confirmed, tympanotomy flap closed and hearing was tested by whispered voice.We usually used 5 mm X 0.6 mm teflon piston (Gyrus fluroplastic piston).

Results
A total of 54 stapedotomies had complete data for analysis.There were 53 patients (52 unilateral and 1 bilateral surgeries) with 30 males and 23 females; male: female ratio was 1.The average of post-operative ABG for 0.

Discussion
The present study, in agreement with the previous published studies 10,[14][15][16][17][18] showed the relevance of stapes surgery especially as regards improvement in the hearing status of patients with otosclerosis.The reason for marginal male preponderance in this study is not known as the disease is known to be predominant in female [1][2][3][4][17][18][19][20][21] .
Various fenestration techniques for stapes prosthesis implantation had been described 14,17,[21][22][23] .Sergi et at 22 reported the use of Laser fenestration technique and concluded that laser stapedotomy is an effective and safe procedure for the treatment of otosclerosis.Yavuz et al 21 in their study "Reliability of microdrill stapedotomy: comparison with pick stapedotomy:" concluded that the microdrill and pick stapedotomy techniques produced similar hearing results and complication rates and recommended that the microdrill can be a useful technique in performing a stapedotomy.In our center, micro-drill fenestration technique with Teflon prosthesis (fluroplastic piston, of appropriate size) is generally used for all our patients.The pre and post operative hearing evaluation (table 2) revealed marked improvement in the patients' hearing status as greater number had closure of their air-bone gap across all the frequencies tested (0.5. 1, 2 an 4 kHz).Average air-bone gap of 61.1% complete closure and 85.2% of closure to within 20 dB seen in this study is comparable with report from many published studies.Sergi et al 22 in Italy reported progressive closure of air-bone gap that began in the early postoperative period and continued to improve through the late post-operative period.Our outcome is similar to the findings of Vincent et al 24 in France who reported ABG closure of < 10dB in 63.4% and < 20 dB in 74.6% of their patients.Kuo et al 20 in Taiwan compared Nitinol prosthesis with the conventional prosthesis and reported ABG closure to within 10 dB in 75% of the patients with Nitinol piston and 33.3% in the patients with the conventional piston.Bast et al 14 reported ABG closure (< 10 dB) in 78% of their cases and Babighian et al 25 reported ABG < 10dB in 54% of their series.
Although 94.4% of the patients achieved some level of closure of ABG and 81.5% achieved ABG closure of ≥ African Health Sciences Vol 16 Issue 1, March 2016 10dB from the present study, success in stapes surgery had been a subject of controversy and there had not been a consistent conclusion 20 .Emphasis has however been placed on post operative ABG closure of within 10dB as a measure of surgical success 26,27 .Going by this, 61.1% success as obtained from this study is comparable to findings from many previous published studies 14,20,22,24,25 .
Factors that influenced surgical outcome in stapes surgery had been extensively discussed 14,20,22,[28][29][30][31] .Babighian et al 25 reported that outcome of revision surgery in stapedotomy is less favourable than the primary one.Kursten et al 28 in their report "Long term result after stapedectomy versus stapedotomy", they concluded than stapedotomy gave better results and that stapedotomy should be the preferred surgical technique in the treatment of otosclerosis.In our present study stapedotomy is generally performed with Teflon piston as implant.
Complication can occur during stapedotomy even in the experienced hand, and to minimize the complication rate, the most experienced senior surgeon performed all the surgeries.All the observed (minor) complications in this study resolved within six weeks after surgery.Major complications in stapes surgery can militate against better outcome and may necessitate revision surgery 25,31,32 .Revision surgery is known for poorer outcome, every effort should be geared against this, and hence the need for experience, appropriate surgical technique and attention to details in stapes surgery cannot be over emphasized.Other factors that may contribute to failure of hearing improvement postoperatively include; prosthesis displacement 24 , preoperative tympanosclerosis and advanced otosclerosis with associated sensorineural hearing loss 31 and oval window fibrosis 25,32 .These factors were already taking into consideration as all our patients had preoperative otomicroscopy to exclude tympanosclerosis and proper surgical technique of stapedotomy that is associated with less postoperative complications.

Conclusion
Stapedotomy is an effective surgical procedure for the treatment of otosclerosis which leads to improvement in patients' quality of life.A good and favorable hearing outcome can be obtained by the combination of experienced hands with minimal surgical trauma and an appropriate surgical technique.This will ultimately lead to less post-operative complications and the need for revision surgery with its attendant poorer outcome.

table 1 .
3: 1.The age of the patients ranged from 18 to 70 years with a mean age of 42.02 ± 12.87 years and age group 31 -40 year were the most affected group (31.2%).The age sex and laterality of the ear operated are shown in African Health Sciences Vol 16 Issue 1, March 2016