Hearing status before and after Stapes surgery in otosclerotic patients

Background: Otosclerosis is a disease of the otic capsule that is characterized by resorption and redeposition of bony tissue. Stapes surgery has established its position as the primary treament of conductive hearing loss in otosclerosis. It is anticipated that the hearing level of approximately 90% of pateitns should improve after surgery. Objective: To evaluate the hearing status of an otosclerotic patient and compare their pre operative and postoperative hearing status. Methods: In this prospective study, 34 patients with otosclerosis from head-Neck Surgery department of Sir Salimullah Medical College & Mitford Hosital, Bangladesh ENT Hospital, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. Period from January 2008 to December 2008. The patients were examined and hearing assessment after admission into the hospital pre-operatively and in the post operative period. Results: In this study most of the cases were age group 21-30 years (50%), male (64-71%), middle socio economic condition (67-71%), rural (58-82%), primary educated (35-29%). It was obsorved that most common symptom was progressive deafness, duration of hearing loss was 2-5 years, pre-operative conductive type of hearing loss (50-55 dB). It was also observed that after surgery, hearing status were improved in 82.35% cases, the most of the patients were within 21-30 years age group. Conclusion: Stapedotomy obtaining closure of the air-bone gap to within 10dB of the preoperative bone conduction level in 90% of their patients. So, it is supperior to other procedures. Key wards: Otosclerosis, conductive hearing loss. A-B gap, Stapedotomy. 1. Assistant professor, National Institute of ENT, Dhaka. 2. Associate Professor, Shahid M. Monsur Ali Medical College, Sirajgong. 3. Assistant Professor, National Institute of ENT, Dhaka. 4. Registrar, National Institute of ENT, Dhaka. 5. Former Professor & Director, National Institute of ENT, Dhaka. Address of correspondence : Dr. Md. Nazmul Hoque, Asst. Prof. National Institute of ENT, Dhaka. E-mail: dr.nazmul.haque1971@gmail.com Introduction Otosclerosis is a familial and genetically determined process inherited as an autosomal dominant Penetrance. It is a diseese of the otic capsule that is characterized by resorption and redeposition of bony tissue. Otoselerosis was first described in 1861 by J. Toynbee. The characteristic lession of otosclerosis first causes fixation of the anterior portion of the foot plate (fistulae ante fenestram) and then total ankylosis of the stapes resulting in conductive hearing loss. It is the most common etiology of conductive hearing loss in 15-50 years old patients with intact tympanic membrane. A higher incidence of the disease in families and homozygotic twins. Women are frequently affected by this pathology than men in at a 2:1 ratio. Stapes surgery has established its position as the primary treatment of conductive hearing loss in otosclerosis. Stapes surgery gained its actual definition in the 1950s with the stapedectomy operation proposed by Rosen in 1953 and the stapedotomy operation introduced by Shea. Adequate bones conduction is a fundamental prerequisite for a successful outcome of a subsequent operation for Otosclerotic disease. Surgery may be inadvisable in cases in which there is pre-existing bone conduction deficit. Complications following stapes surgery are rare. The techniques used for stapes surgery have evolved gradually over four decades, with multiple variable to contend with including fenestration size and technique, graft material, prosthesis diameter and design, tendon repair, pathological severity and surgical expertise. Regardless of the technique, it is anticipated that the hearing level of approximately 90% of patients should improve after surgery and that less than 1% of patients should have severe sensorineural hearing impairement following surgery. Objectives 1. To evaluate the hearing status of as otoseterotic patient at the time of presentation. 2. Comparison between pre operative and post operative hearing level. Methods Type of study: Prospective study. Number of cases: 34 Study population: Patients admitted in the hospital with Otosclerosis for stapes surgery. Duration of study: January 2008 to december 2008. Places of study: Department of Otolaryngology and Head-Neck Surgery in Sir Salimullah Medical & Mitford Hospital, Dhaka, Bangladesh ENT Hospital , Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka. Inclusion Criteria: • Air bone gap was not less than 20 dB. • Air conduction loss was not more than 70dB. • Bone conduction loss was not more than 30dB. Exclusion criteriapatients dropped out from follow up. Data collection method: By questionnaire, clinical examination and audiological investigations. Data analysis: By computer and manual calculator. Results Table I Age of patients (n-34) Age 11-20 years 21-30 years 31-40 years 41-50 years Number of patients 2 17 13 2 Percentage 5.88% 50% 38.23% 5.88% Most common age group were 21-30 years (50%). This table shows 22 (64.71%) patients were male. 138 Hearing status before and after Stapes surgery in otosclerotic patients Md. Nazmul Haque et al


Introduction
Otosclerosis is a familial and genetically determined process inherited as an autosomal dominant Penetrance. It is a diseese of the otic capsule that is characterized by resorption and redeposition of bony tissue 1 .
Otoselerosis was first described in 1861 by J. Toynbee 2 . The characteristic lession of otosclerosis first causes fixation of the anterior portion of the foot plate (fistulae ante fenestram) and then total ankylosis of the stapes resulting in conductive hearing loss.
It is the most common etiology of conductive hearing loss in 15-50 years old patients with intact tympanic membrane 3 . A higher incidence of the disease in families and homozygotic twins 4 . Women are frequently affected by this pathology than men in at a 2:1 ratio 5 .
Stapes surgery has established its position as the primary treatment of conductive hearing loss in otosclerosis 6 . Stapes surgery gained its actual definition in the 1950s with the stapedectomy operation proposed by Rosen 7 in 1953 and the stapedotomy operation introduced by Shea 8 . Adequate bones conduction is a fundamental prerequisite for a successful outcome of a subsequent operation for Otosclerotic disease. Surgery may be inadvisable in cases in which there is pre-existing bone conduction deficit 9 . Complications following stapes surgery are rare 10 .
The techniques used for stapes surgery have evolved gradually over four decades, with multiple variable to contend with including fenestration size and technique, graft material, prosthesis diameter and design, tendon repair, pathological severity and surgical expertise.
Regardless of the technique, it is anticipated that the hearing level of approximately 90% of patients should improve after surgery and that less than 1% of patients should have severe sensorineural hearing impairement following surgery. 2. Comparison between pre operative and post operative hearing level.

Methods
Type of study: Prospective study. Inclusion Criteria: • Air bone gap was not less than 20 dB.
• Air conduction loss was not more than 70dB. • Bone conduction loss was not more than 30dB.
Exclusion criteria-patients dropped out from follow up.
Data collection method: By questionnaire, clinical examination and audiological investigations.
Data analysis: By computer and manual calculator.  Most common symptom was progressive Deafness. Most of the patients had conductive type of hearing loss in between 50-55 dB. Most of the patients had conductive type of hearing loss in between 50-55 dB.   Hearing status improvd in most of the patients within age of 21-30 years.

Discussion
In the series most common age group was 3 rd decade. The next common group was 4 th decade. This is supported by Gray and Smyth. The sex ratio varies from series to series. But our finding is almost similar to Lid and Cao.
In the present series the common symptoms were progressive hearing loss (100%), tinnitus (11.76%) and vertigo (23.53%). This is supported by most of authors like Katjenmayer, Smyth and Gray 2,5,11 .
The paracusis Willisii was noticed by most of the patients (32) this finding is similar to most authors (Ozgirgin) 6 . Here 12 patients (35.29%) had hearing loss of 2-5 yerars duration and 8 patients (23.53%) had hearing loss of 5-10 years duration.
In this series one patient (2.94%) had facial palsy which was transient in nature and taste disturbance occurred in 3 cases due to injuries to charda tympani nerve. Li and fisch observed similar type of injuries 4,12 .
Analysis of the audiological results showed that most study patients achieved considerable auditory gain after surgical operation. The presented data demonstrates a major improvement of air bone gap in younger patients. Among the improvement, the largest improvement was of 25 dB and least improvement was of 20dB.
Hearing gain was obtained in 28 cases that is about 20-25 dB and no gain was recorded in 6 cases. Improvement was 82.35% where as no improvement was 17.65%. There was no reported case of deterioration of hearing in this study. This findings correlates with the findings of MH Baradaranfar and P Dabirmoghaddam, Mahfuxz Z and Lokman S, Song HM, Choi SJ and Lee KS 13 . None of the patients complained of significant vertigo and tinnitus in post operative follow up. This indicates that hearing status was improved after stapes surgery in otosclerotic patients.

Conclusion
There has been much debate regarding results of total stapedectomy vs. partial stapedectomy vs. stapedotomy. Recent stapedotomy technique (with fewer complicciations) and thus there has been a recent shift toward this procedure. Most consider stapedotomy to be technically easier to perform with less potential damage to the vestibule. So, it is superior to other procedures.