Stapes Surgery in Far-Advanced Otosclerosis

Abstract

Introduction:

Surgical treatment of patients with far-advanced otosclerosis (FAO) has not yet been standardized. Patients with FAO are the candidates for stapes surgery or cochlear implant (CI). Although many surgeons consider stapes surgery as the first choice, other authors prefer CI because of the excellent hearing results.

Objective:

The authors discuss their experience in the treatment of patients with FAO, potentially candidates for CI, who underwent stapedotomy.

Materials and Methods:

Eleven adult patients with FAO underwent stapedotomy from 2006 to 2016. Pure-tone average (PTA) between 0.5-1-2-3 kHz and speech perception test with hearing aids were determined before and after stapedotomy.

Results:

The results show a statistically significant improvement in air condition threshold (PTA) and satisfactory results with regard to speech recognition in 9 (81.8%) cases. Postoperative results are not influenced by the type of stapedotomy prosthesis employed and do not change during follow-up (3 years).

Conclusions:

The authors suggest first performing stapes surgery in patients with FAO and reserving CI in case of failure.

Introduction

Far-advanced otosclerosis (FAO) was first described by House and Sheehy ¹ as a rare clinic condition with an air-conduction (AC) threshold of at least 85 db HL and an unmeasurable bone-conduction (BC) threshold (due to the limitations of the audiometer at that time). Very far-advanced otosclerosis, otherwise, indicates patients with unmeasurable AC and BC thresholds, resulting in blank audiogram. ²

With time and improvement in audiometric equipment, the definition changed, but, to this day, there is no clear universal definition used. ³

In the era of cochlear implantation (CI), speech discrimination scores are more likely to be used instead of pure-tone thresholds ⁴ and the term far-advanced otosclerosis is often used to describe patients with otosclerosis with severely decreased speech recognition abilities. ³

The difficulty in diagnosing and the low incidence of these conditions explain the uncertainties concerning the therapy and the risk of failure to differentiate patients with otosclerosis with a blank audiogram from other postlingually patients with totally hearing disability who are the candidates for CIs. ⁵

In advanced otosclerosis, characterized by mixed hearing loss, hearing aids alone often do not result in optimal hearing rehabilitation, and surgery becomes an option. Nowadays, 4 main treatment modalities are available for FAO: Hearing aids may be used especially in patients who are not suitable for surgery; stapedotomy and hearing aid; stapedotomy combined with active middle ear implants, ^4,6 and, lastly, CI. ^{7 -10}

The decision for the appropriate treatment for each patient can be challenging, given that both stapedotomy and CI differ in costs, risks, and success rate. ^3,4,11,12 Some authors propose CI surgery as the first treatment and alternative to stapes surgery ¹³ for these patients, while others indicate stapes surgery as the initial treatment in patients with FAO, followed by hearing aids. ^{3,11,12,14,15}

Clinical evidence describing high success rates using CI in patients with severe hearing loss ^4,13,16,17 However, there is also much evidence to suggest that stapes surgery can restore hearing to acceptable levels in patients with profound hearing loss and that correction of only the conductive component can be effective enough to achieve acceptable hearing, ⁴ especially when combined with a well-fitted hearing aid ^{3,5,6,15,18,19} and also considering the advancement in stapes surgery ²⁰ and hearing aids technology.

Furthermore, whereas CI can be physically invasive with risks of difficult or incomplete insertion or facial nerve stimulation and it requires enrolment in a rehabilitation program, stapes surgery is minimally invasive and cost-effective. ^3,6,12 If stapes surgery is not beneficial, if hearing remains insufficient or decreases with time after stapedotomy, patients can still be treated with CI. ^4,11,12

The aim of this study is evaluate the stapedotomy hearing results in patients with FAO who are often referred to CI.

Materials and Methods

A retrospective analysis was conducted with patients with FAO who underwent stapes surgery, performed by otolaryngologists—head and neck surgeons of Vanvitelli University and S. Maria delle Grazie” Hospital—Pozzuoli (Naples), from 2006 to 2016. Our inclusion criteria were a hearing loss attributed to otosclerosis, an AC pure-tone average (PTA) threshold below 90 dB, and a disyllabic Word Recognition Score (WRS) with well-fitted hearing aids less than 50% at 60 dB HL. They were all patients eligible for CI according to both National Institute for Health and Care Excellence (NICE) recommendation ²¹ and many current European guidelines indicating CI in adults. ^4,22,23

The study group consisted of 11 adult patients (6 males and 5 females), mean age 69 (range 50-81). The surgical procedure performed on all 11 patients consisted of primary stapedotomy on the poorer hearing ear, under local anesthesia with sedation. The surgeons (M.L. and M.G.) placed platinum fluoroplastic prosthesis (Richards) in 6 cases and titanic prosthesis (Kurtz) in 5 cases; the length of the prosthesis was 4.5 mm in 9 cases and 4.75 mm in 2 cases, with a diameter of 0.6 mm in 9 patients and of 0.4 mm in 2 cases. No patients underwent bilateral surgery. Preoperative and postoperative PTA was calculated according to the American Academy of Otolaryngology Head and Neck Surgery Committee of Hearing and Equilibrium guidelines for the evaluation of results of conductive hearing loss treatment ²⁴ and averaged on 500, 1000, 2000, and 3000 Hz. Moreover, the preoperative and postoperative speech perception test was administered in open field with bilateral hearing aids, to obtain the open-set WRS at 60 dB HL. All postoperative audiological tests were carried out 30 days, 6 months, 12 months, and 3 year after surgery. Postoperative follow-up was at least 3 years. In order to complete the diagnostic process and to plan surgical procedure, high-resolution computed tomography (HRCT) of the petrous bone was performed in all the patients.

Statistical Analysis

Student t test was used to compare the means of the preoperative and postoperative hearing results. The P values of <.05 were considered to be statistically significant.

Results

The diagnosis of FAO was confirmed in all patients during the surgery, all patients were found to have otosclerosis of the oval window.

The mean preoperative AC PTA was 101.47 (±7.454) dB HL, ranging from 93.75 to 115 dB HL; with hearing aids, the mean preoperative WRS was 11.36% (range 5%-20%). The entire study group gets a mean postoperative pure-tone audiometry of 78.06 (±13.54) dB HL (range 58.75-100 dB HL), demonstrating a significant increase when compared with the mean preoperative score (P < .001). All the patients included in this study achieved a mean postoperative open-set WRS, with hearing aids, of 58.18% (range 20%-75%). None of the operated patients had intraoperative or postoperative complications; only in 1 case, there was dizziness with nausea and vomiting lasting 48 hours. Preoperative and postoperative PTA without hearing aids and speech audiometry results with hearing aids are given in Table 1 for each single patient. The mean preoperative and postoperative PTA without hearing aids and speech audiometry results with hearing aids are given in Table 2 and were found statistically significantly better after surgery (P < .001). The results are not influenced by the surgeon (P = .5) and the type of stapedotomy prosthesis (P = .29). It was 2 women in both cases of failure. The results were not affected by age. An improvement of air condition threshold (PTA) was obtained in 9 of 11 cases (81.8%). Postoperative results do not change during follow-up, at 30 days, 6 months, 12 months, and 3 years after surgery. The speech recognition score after stapedotomy is more than 30% in 10 (90.9%) of 11 patients and more than 50% in 9 (81.8%) of 11 patients, and, therefore, they are no longer candidates for the CI according to both NICE ²¹ and many current European guidelines indicating CI in adults recommendation. ^4,22,23 In none of these patients, the radiographic appearance at HRCT was suggestive of obliterative cochlear otosclerosis.

Table 1.

Summarized Preoperative and Postoperative Hearing Results for Each Patients.^a

Patient	Gender, age (year)	Surgical procedure	Preoperative AC-PTA (dB HL)	Postoperative AC-PTA at 3 years of follow-up (dB HL)	Preoperative communicative performances (WRS%)	Postoperative communicative performances at 3 years of follow-up (WRS%)
1	M, 50	Right stapedotomy	93.75 ± 4.78	58.75	20	75
2	F, 80	Right stapedotomy	95 ± 4.08	65	15	70
3	F, 77	Right stapedotomy	110 ± 4.08	82.5	10	60
4	F, 74	Left stapedotomy	96.25 ± 2.5	67.5	10	65
5	M, 66	Left stapedotomy	97.5 ± 6.45	80	10	55
6	F, 55	Left stapedotomy	115 ± 7.07	100	5	20
7	M, 79	Right stapedotomy	95 ± 4.08	67.5	15	65
8	F, 81	Right stapedotomy	110 ± 4.08	100	5	35
9	M, 64	Left stapedotomy	102.5 ± 10.4	85	15	60
10	M, 68	Right stapedotomy	105 ± 8.16	72,5	10	70
11	M, 70	Left stapedotomy	96.25 ± 2.5	80	10	65

Abbreviations: AC, air conduction; PTA, pure-tone average; WRS, Word Recognition Score.

^a Speech recognition was tested in free field with bilateral hearing aids. Bone conduction is unmeasurable in all cases.

Table 2.

Mean Preoperative and Postoperative Air-Conduction Pure-Tone Average and Word Recognition Score in Study Group.

Test type	Total group
Preoperative test results
AC-PTA	101,47 dB HL (±7,45)
WRS	11,36% (range 5%-20%)
Postoperative test results
AC-PTA	78.06 dB HL (±13.54)
WRS	58.2% (range 20%-75%)

Abbreviations: AC, air conduction; PTA, pure-tone average; WRS, Word Recognition Score.

Discussion

The treatment of FAO has evolved over the past 20 years along with the evolution of the hearing aid technology and the advent of CIs as an alternative of treatment.

A little number of patients with otosclerosis has an audiometric profile that could justify a CI, and when history, clinical features, and radiologic imaging confirm the diagnosis, a decision has to be made between a stapedotomy with hearing aids or a CI as a first option. ^3,4,6,11,12

During the past decades, numerous studies have evaluated CI as a treatment for patients affected by FAO. ^12,16,17 Cochlear implant has yielded excellent results and seems to be a good treatment for patients with advanced otosclerosis. ^16,25,26

Some authors propose an algorithm for the treatment of patients with advanced otosclerosis. Patients are divided into 3 main groups using standard speech audiometry: maximum SD scores of <30%, 30% to 50%, and 50% and 70%. They indicate CI in first category of patient. In cases of speech recognition scores between 30% and 50%, they base their decision on the extent of the air–bone gap and on findings of HRCT scanning, considering CI in case of severe cochlear otospongiosis. ^4,12

The role of CT scan in otosclerosis continues to be debated, even though some authors recommend it as the gold standard for diagnosis, ^27,28 with a sensitivity of 66% to 95%. ⁴ Most recent studies showed that nearly 90% of petrous bones with fenestral otosclerosis are identified by HRCT. ²⁹ Different grading systems (Rotteveel ³⁰ and Symons/Fanning ⁴ ) are available for the classification of otosclerosis. Both are based on the location of the otosclerotic lesions: solely fenestral (grade 1), patchy retrofenestral (grade 2), and diffuse confluent retrofenestral involvement (grade 3). ^1,4 Because HRCT can detect subtle otosclerotic foci in and around the cochlea, it may predict the risk of complications during surgery. ⁴

Merkus et al ⁴ in a systematic review of the literature shows excellent results in patients affected by FAO and treated by CI with better hearing in 100% of the patients and postoperative speech perception between 45% and 98%, depending on the test used, versus a speech perception between 38% and 75% after stapedotomy.

Nevertheless, CI is not without disadvantages. It requires implication in a re-education program, is more invasive, and is much more expensive than stapedotomy. It is an expensive procedure that requires experienced surgeons, especially because spongiosis and sclerosis can cause problems during implantation. ^3,4,6,12

Stapes surgery has been proposed as the first treatment in patients with FAO by many authors during the past decades: Shea et al ³¹ demonstrated that 42% of 60 patients with absent preoperative BC thresholds had measurable thresholds after the surgery and the hearing was restored to an aidable level.

Lippy et al ³² noted in 24 patients with FAO, operated by stapedectomy, the WRS had improved in 16% at 1 month after the surgery and reached 33% after 2 years.

Frattali and Sataloff ¹⁸ described 70% patients with FAO reached aidable hearing level after surgery. In 1996, Glasscock et al ³³ showed that stapedectomy was effective in 60% of patients with advanced otosclerosis and FAO.

The recent studies by Kabbara et al ⁶ and van Loon et al ¹² showed a successful outcome (defined as a postoperative WRS greater than 50% with a well-fitted ipsilateral hearing aid) in, respectively, 60% and 72% of patients who received a stapedotomy. Although the successful outcome of CI group of patients was better, these studies show that stapedotomy can still be very effective in treating this group of patients.

It must be underline that, according to some authors, ^14,32,34 the criteria to establish the success of a surgical procedure in the treatment of patients with FAO is a mixture of objective and subjective parameters: The first is represented by the improvement in the postoperative pure-tone and speech audiometry results, while the second consists of the improvement in the use of hearing aids. The ideal result of treatment should be to convert the hearing of patients with FAO from nonserviceable to serviceable with conventional hearing aids.

After stapedotomy, only hearing and fitting is required, whereas CI is followed by an intensive rehabilitation program. The quality of sound is more natural after stapedotomy and, consequently, the appreciation of music is likely to be better preserved. ¹²

The electrical stimulation provided through a CI is less than optimal, with a limited dynamic range and a lack of ability to deliver detailed spectral information that helps define the pitch and timbres of music. This leads to poor music appreciation, extremely poor melody perception, and worse discrimination in loud environments. Acoustic stimulation through hearing aids, when effective, provides better overall sound quality. ⁶

Another field of debate is if it is correct to carry out a stapes surgery in the other ear if there has been improvement after the first stapedotomy; some authors considered the second surgery is justified to restore a complete binaural amplification. ^14,18 Bilateral stapedotomy would further increase the number of patients with good audiologic performance. ^3,12,14

Compared to CI, the stapes surgery is less expensive and the procedure is less complex and has less risks and less rehabilitation time. ^{3 -6,12} Stapedotomy can also be performed under local anesthesia, making stapedotomy especially applicable for the elderly and patients with comorbidities. ¹² When (bilateral) stapedotomy does not yield a satisfactory result, the option of CI is still open because a previous ipsilateral stapedotomy will not affect the outcome or performance of CI. ^{4,11,12,16,17,35}

Another point to consider is that hearing aids are always advancing with technology so that the hearing improvement after stapes surgery could be more and more powerful in the future. We report, in our study, satisfactory results with regard to speech recognition (81.8% of the patients) without any significant complications.

Patients with otosclerosis may demonstrate a further progression of sensorineural hearing loss that cannot be explained by age alone. ^36,37 To date, the exact rate of this progression remains unclear. Currently, there are no prognostic factors that could accurately predict failure after stapedotomy in patients with FAO. Age, sex, preoperative PTA, and preoperative speech recognition scores do no predict the outcome after stapedotomy. ¹² More studies with longer follow-up are necessary.

Limits of this study are the retrospective design and the small number of cases.

Conclusions

In patients with FAO, the stapes surgery should be considered as the first surgical option, considering the good success rate (81.8%) with the possibility to provide aidable hearing in high percentage of cases and the continuous progress of hearing aids. The authors suggest first performing stapes surgery in these patients and reserving CI in case of failure.