Experience with stapedectomy in a developing country: A review of 200 cases. (Original Article).

Abstract

Since stapedectomy was first performed in 1956, many innovations have been described. We retrospectively analyzed 200 cases of stapedectomy that had been performed with standard otologic instruments. Of the 200 patients, 54 (27.0%) had significant sensory deafness associated with footplate fixation. In most cases, the footplate was partially removed (stapedotomy group); in the remainder, the footplate was removed in its entirety or subtotally (stapedectomy group). Of the 200 patients, 163 were available for short-term follow-up. The air-bone gap was closed to within 10 dB in roughly 83% of both groups. Although long-term follow-up was possible in only a limited number of cases, we believe that an experienced otologist working with standard equipment and a basic operating microscope can obtain satisfactory stapedectomy results with minimal complications.

Introduction

Stapedectomy was first performed for otoscierosis in 1956. Although the basic principles of surgery have remained unchanged, several innovative and expensive techniques have been introduced during the past 2 decades. They include the use of sophisticated lasers to make openings in the footplate and prostheses that differ in design and composition to suit the preferences of individual surgeons. Intricate modifications in surgical technique range from leaving behind the posterior crus of the stapes (1) to reattachment of the stapedius tendon to the prosthesis. (2)

In the developing world, where otosclerosis is common and financial resources are limited, it is possible to achieve excellent results with traditional stapedectomy techniques, standard otologic instruments, and cost-effective prostheses. In this article, we review our experience with 200 stapedectomies performed at two hospitals in Karachi, Pakistan.

Patients and methods

We retrospectively studied 200 primary stapedectomies performed between 1982 and 1996 by a single surgeon (I.S.). The 110 males and 90 females ranged in age from 15 to 70 years (mean: 37); 11 patients were older than 50 years, and four patients were younger than 20 years. Because postoperative audiograms were not available for 37 patients, they were excluded from the tabulation of hearing results, but the data regarding their disease and surgery are included in other results. Women, particularly those contemplating matrimony, were particularly enthusiastic to undergo surgery that would obviate the need for a hearing aid.

Otosclerosis was predominantly bilateral (83.0%), but interestingly enough, only six patients returned for surgery on the opposite ear. This reflects not only a reluctance to undergo further surgery after hearing was restored in the operated ear, but also the financial constraints faced in a country where health insurance is uncommon.

Audiograms were obtained in a soundproof room with audiometers (Grason-Stadler models No. 10 and No. 16) calibrated to Iso 1969 standards. The local language (Urdu) list was used for patients who did not speak English. Preoperatively, the average speech reception threshold was 66.3%, and the average speech discrimination score was 88.9%. When average bone conduction levels at 500 to 2,000 Hz were calculated, 54 patients (27.0%) demonstrated sensory deafness of 30 dB or more; 16 of them had profound deafness (90 dB), but their conductive component was sufficient to merit surgery. Impedance audiometry was performed occasionally, but tuning-fork tests were critical in evaluating patients and in planning surgery.

Drill and laser facilities for middle ear surgery were not available at either of the two hospitals. Instead, we used standard otologic instruments and a basic operating microscope (Zeiss OPMI-1). Local anesthesia with sedation was administered to all but three patients; general anesthesia was employed in a 15-year-old patient and in two patients who became restless during the procedure.

A transmeatal incision was made in all but two patients, whose narrow canal required an endaural incision. A guide opening was always made in the footplate prior to disarticulation of the incudostapedial joint. In situations where avulsion of the stapes superstructure resulted in a floating footplate, the guide opening facilitated its retrieval. While enlarging the guide opening, an effort was made to keep the size just large enough to accept a 0.6-mm prosthesis; such a procedure was considered a stapedotomy. If more than half the footplate came away, the procedure was considered a stapedectomy. In all cases, McGee stainless-steel piston prostheses were used (these prostheses are readily available at a reasonable price). While crimping the prosthesis over the incus, it was occasionally difficult to stabilize the lower end of the piston. A simple remedy in such situations was to place adipose tissue around the piston before attempting to crimp the prosthesis.

Six patients had an obliterated footplate. Trephination was successful in two of these patients. However, in the other four patients, it was not possible to remove any portion of the footplate, and the procedure was discontinued.

Results

In reporting the results of surgery for conductive deafness, many parameters have been defined. (3) Although absolute postoperative air conduction thresholds and speech discrimination scores reflect hearing improvement, closure of the air-bone gap indicates the efficiency of the reconstructed sound conduction mechanism. In this study, we used the postoperative bone conduction level as the reference to measure the degree of closure of the airbone gap.

Postoperative audiograms were available for 163 of the 200 patients (81.5%); the others were lost to follow-up and were not included in the tabulation of hearing results (table). Of the 163 patients, 114 (69.9%) had the footplate partially removed (stapedotomy group). In this group, the air-bone gap was closed to within 10 dB in 95 patients (83.3%) and to within 20 dB in 14(12.3%). Five stapedotomy patients (4.4%) experienced either no improvement or a worsening of their hearing.

The 49 patients in the stapedectomy group (30.1%) had the footplate either completely or subtotally removed. The air-bone gap was closed to within 10 dB in 41 of these patients (83.7%) and to within 20 dB in five patients (10.2%). Three patients (6.1%) experienced either no improvement or a worsening of their hearing.

In the two groups combined, 136 of the 163 patients (83.4%) experienced closure of the air-bone gap to within 10 dB and 19(11.7%) to within 20 dB. Only eight patients (4.9%) experienced either no improvement or a worsening of their hearing. All four patients who were younger than 20 years of age had their air-bone gap closed to within 10 dB. Twenty-six of the 136 patients who experienced complete air-bone closure were followed up for a period of 2 to 10 years. In all 26, the gap had remained closed. However, the number of these patients is too small to derive any conclusions about the long-term stability of the conduction mechanism.

Complications were rare. Five of the 200 patients (2.5%) experienced flap perforation, one (0.5%) had a floating footplate, and one experienced an injury to the high jugular bulb. There was no instance of facial nerve injury.

Discussion

Otosclerosis is known to invade the middle layer of the otic capsule and cause sensory deafness. Schuknecht and Barber reported that pure cochlear otosclerosis without involvement of the footplate occurred in only 3% of temporal bones. (4) In their study of 164 temporal bones with otosclerosis, they found that up to the age of 69 years, the incidence of sensory deafness was not much higher in patients with stapedial otosclerosis than it was in agematched controls. Shea's experience, however, was different. (5) He found that most patients younger than 50 years who underwent stapedectomy developed progressive sensory deafness. Similar findings were reported by Smyth and Hassard, who found that most patients who underwent stapedectomy experienced a progressive deterioration in bone conduction levels that reached the point of nonserviceable hearing. (6) The benefit of surgery, however, was that it allowed these patients to get by with unaided hearing for 17 to 21 years.

In our series, 54 of the 200 patients (27.0%) had preoperative sensory deafness of 30 dB or more. This high incidence might have been secondary to the incidence of chronic suppurative otitis media during childhood and its sequelae, which are common in our population. Marriage of consanguineous partners is common in Pakistani culture. Because otoscierosis is an autosomal-dominant disease, it is possible that the patients in our study had an aggressive variant of the disease. This hypothesis needs further study.

Even though stapedectomy procedures have been performed extensively over the past 40 years, concerns remain about the long-term durability of hearing. Understandably, many otologists are reluctant to offer stapedectomy to young patients with otosclerosis, suggesting that they use a hearing aid instead. Published data on otosclerosis in children are sparse. In one such report, Robinson studied 610 patients who had developed otosclerosis before the age of 18 years. (7) Based on the outcomes of 38 stapedectomies, he concluded that children with otosclerosis have a high incidence of obliterative disease and that postponing surgery only worsens the footplate pathology, which makes subsequent surgical procedures more difficult. Cole reported excellent outcomes following stapedectomy in 62 patients younger than 20 years. (8)

In 1978, Smyth and Hassard published their comparison of small-fenestra and large-fenestra stapes surgeries, in which they questioned the necessity of removing the footplate completely. (9) They reviewed the results of 800 small and large procedures and reported that although hearing gains were similar in the two groups, those who underwent stapedotomy had a lower risk of developing fistulae or sensory neural deafness. In 1981, McGee published his experience with 280 cases of stapedectomy and concluded that the size of the fenestra was inversely proportional to the amount of hearing gain. (10) McGee preferred the small-fenestra technique as the treatment of choice. In 1982, Shea, who had performed the first stapedectomy in 1956, concluded that immediate and long-term hearing gains were equally good regardless of whether the footplate was partially or completely removed. (11)

In our series, we found that the rates of significant hearing gains in the two groups were almost identical (~83%). However, partial stapedectomy is a safer technique inasmuch as only a limited area of the vestibule is exposed and the gap in the footplate around the prosthesis can be easily sealed with viable tissue. The stapedectomy technique is based on sound principles, and when it is performed by an experienced surgeon, satisfactory results can be achieved with standard otologic instruments. Stapes replacement prostheses are now available at a reasonable price in most countries, which offers an opportunity to many patients who heretofore could not hope to enjoy the benefits of unaided hearing.

Table. Hearing results (n [%]) following surgery

                              Stapedotomy  Stapedectomy    Total
                               (n = 114)     (n = 49)    (n = 163)

Air-bone gap closed to 10 dB   95 (83.3)    41 (83.7)    136 (83.4)
Air-bone gap closed to 20 dB   14 (12.3)     5 (10.2)     19 (11.7)
Not improved or worse           5 (4.4)      3 (6.1)       8 (4.9)

References

(1.) Hough JV, Dyer RK, Jr. Stapedectomy. Causes of failure and revision surgery in otosclerosis. Otolaryngol Clin North Am 1993;26:453-70.

(2.) Causse JB, Vincent R, Michat M, Gherini S. Stapedius tendon reconstruction during stapedotomy: Technique and results. Ear Nose Throat J 1997;76:256-8, 260-9.

(3.) Goldenberg RA, Berliner KI. Reporting operative hearing results: Does choice of outcome measure make a difference? Am J Otol 1995;16:128-35.

(4.) Schuknecht HF, Barber W. Histologic variants in otosclerosis. Laryngoscope 1985;95:1307-17.

(5.) Shea JJ. Thirty years of stapes surgery. J Laryngol Otol 1988;102:14-9.

(6.) Smyth GD, Hassard TH. Hearing aids poststapedectomy: Incidence and timing. Laryngoscope 1986;96:385-8.

(7.) Robinson M. Juvenile otoscierosis. A 20-year study. Ann Otol Rhinol Laryngol 1983;92:561-5.

(8.) Cole JM. Surgery for otosclerosis in children. Laryngoscope 1982;92:859-62.

(9.) Smyth GD, Hassard TH. Eighteen years experience in stapedectomy. The case for the small fenestra operation. Ann Otol Rhinol Laryngol Suppl 1978;87(Suppl 49):3-36.

(10.) McGee TM. Comparison of small fenestra and total stapedectomy. Ann Otol Rbinol Laryngol 198 1;90:633-6.

(11.) Shea JJ. Stapedectomy--long-term report. Ann Otol Rhinol Laryngol 1982;91:516-20.

From the Department of Otolaryngology--Head and Neck Surgery, Aga Khan University Hospital, Karachi, Pakistan.

Reprint requests: Dr. Iftikhar Salahuddin, Head, Department of Otolaryngology--Head and Neck Surgery, Aga Khan University Hospital, Stadium Rd., PO Box 3500, Karachi, Pakistan. Phone: [phone]; fax: [phone] or -2095; e-mail: [e-mail]