Outcomes after laser stapedotomy with and without preservation of the stapedius tendon.

Abstract

Our goal was to investigate the postoperative differences in hearing between patients who had had their stapedius tendon sacrificed and those whose stapedius tendon was preserved during laser stapes surgery for otosclerosis. To that end, we performed a retrospective review by mailing extensive questionnaires to patients who had been operated on between 1994 and 1997. We also performed routine and special audiometric testing to augment the subjective data. Seventy-nine of 124 questionnaires (64%) were returned. Of the respondents, 75 patients had undergone additional pre- and/or postoperative audiometric testing, including tests to evaluate "hearing in noise" and to determine the "uncomfortable loudness level" (dynamic range).

We found no statistically significant differences between the two groups with respect to their subjective responses and their audiologic test results. The responses to the questionnaire indicated that in most cases, hearing was improved by stapes surgery. We conclude that the stapedius tendon should be preserved whenever possible during stapes surgery, provided that it does not jeopardize the exposure or outcome.

Introduction

The literature is replete with reports of standard audiometric assessments of hearing after stapes surgery. The evolution of stapes surgery in the 1950s and 1960s was initially quite rapid. However, since the introduction of laser techniques in the 1980s, the pace of progress toward better, more efficient, and safer methods has slowed. [1,2]

We recently introduced our technique of minimally invasive stapes surgery with preservation of the majority of normal stapedial anatomy, a procedure we call laser stapedotomy minus prosthesis (laser STAMP). [3] With the development of this technique--in which emphasis is placed on effective treatment with preservation of normal functional anatomy--additional interest has developed in preserving the stapes tendon whenever possible during stapes surgery. [4]

Theoretical reasons to preserve the stapedius tendon during surgery have been cited previously. [5-8] These reasons include 1) a possible reduction in acoustic trauma, 2) a possible reduction in the risk of barotrauma, 3) an improvement in hearing in a noisy environment, 4) stabilization of the incus during prosthesis insertion, and 5) the preservation of the blood supply to the distal incus.

Using a hand-held laser probe, it is technically possible to preserve the stapedius tendon and to provide adequate exposure for reconstructing the ossicular chain during otosclerosis surgery. In cases where there is minimal otosclerosis and a blue footplate, the fixed anterior portion can be separated from the normal posterior stapes footplate with the laser STAMP procedure. When a prosthesis is required, the anterior and posterior crura of the stapes can be vaporized before the prosthesis is inserted. In both these procedures, the stapedius tendon is preserved.

The purpose of this report is to compare subjective and objective data from patients with otosclerosis who have had their stapedius tendon preserved with data from patients who have had their stapedius tendon transected during surgery. The subjective data from the questionnaire have been augmented with the results of standard and special audiologic testing.

Materials and methods

We mailed questionnaires to 124 patients who had been surgically treated for otosclerosis between 1994 and 1997. This survey concerned the quality of each patient's hearing before and after stapes surgery. We received usable data from 79 respondents (64%). Of those, 47 patients had had their tendon sacrificed (group 1), and 32 had had their tendon preserved (group 2). The general characteristics of the patient population are shown in table 1.

Eighteen of the patients in the tendon-preserved group had been treated with the laser STAMP procedure and 14 with the Causse piston technique. (We had originally identified three groups, but because the results in the Causse and the laser STAMP groups were almost identical, we combined them to increase the number of patients for statistical analysis.) Although it would theoretically be more instructive to compare the laser STAMP procedure with and without stapedius tendon preservation, this could not be accomplished because the stapedius tendon is preserved in all laser STAMP procedures.

The subjective outcomes data were tabulated in a computer-based spreadsheet format and subjected to statistical analysis (Systat 7.0.1.; SPSS, Inc., 1997). For parametric analysis, a standard analysis of variance with appropriate planned comparisons was utilized. For nonparametric comparisons, a [X.sup.2] statistical analysis was performed.

All patients underwent standard pre- and postoperative (4-6 wk) audiometric testing. The audiologists were not blinded to the surgical procedure performed, but they were not told any details about this project, so bias probably did not occur. Of the 79 respondents, 75 had undergone special audiometric testing before (when applicable) and after stapes surgery. Each patient was tested with one of three clinical audiometers (Grason Stadler 16, Beltone 222c, or Fonix Fa-10), which were calibrated in accordance with the American National Standards Institute's (ANSI) 1996 specifications. [9] Four patients did not undergo the additional audiologic testing.

All audiometric and speech tests were performed in a sound-treated room that met ANSI's 1991 specifications for permissible ambient noise. [10] Tympanometry and acoustic reflex testing were performed with the Grason Stadler 33 Clinical Immittance Bridge (GSI, calibrated in accordance with ANSI's 1987 specifications). [11] All patients were tested for acoustic reflexes. The patients whose stapedius tendon was sacrificed served as controls. Puretone air and bone conduction thresholds and speech reception thresholds were obtained for each ear. A "most comfortable level" was established for both ears; this level averaged between 25 and 40 dB of sensation. A speech discrimination score was obtained with a Northwestern University (NU6) list of 25 words. Next, ipsilateral masking (speech noise) was introduced at a 0 dB signal-to-noise ratio (noise level equals speech level), and another NU6 list and 10 CID (Central Institute for the Deaf) "everyday sentences" (Cochlear Corp. list 3, 4, or 5) were presented. A "spee ch uncomfortable level" (UCL) and pure-tone UCLs at 500 Hz, 1 kHz, 2 kHz, and 4 kHz were established, using the Siemens explanation chart for UCL.

Thereafter, patients were moved to the GSI 33 room and instructed to stay very still and not speak during this portion of the testing. A tympanogram and measurements of ipsilateral and contralateral reflexes at 500 Hz, 1 kHz, 2 kHz, and 4 kHz were recorded on both ears. The diagnostic mode was used for all of this testing. The stimulus was presented at levels up to 105 dB until either a reflex was obtained or the patient expressed discomfort. This entire procedure was always repeated on the other ear for comparison.

Group 1 consisted of 47 patients who had undergone a laser stapedotomy with prosthesis reconstruction and stapedius tendon sacrifice. These patients had their stapes reconstructed with the Schuknecht wire fluoroplastic piston (0.6 mm diameter; Smith Nephew Richards; Memphis, Tenn.) or the Causse Loop Fluoroplastic piston (0.4 mm diameter; Xomed; Jacksonville, Fla.). Ear lobe adipose tissue was used as a seal.

Group 2 consisted of 32 patients who had undergone a laser stapedotomy with prosthesis or the laser STAMP procedure while their stapedius tendon was preserved. When a prosthesis was required in this group, the Causse prosthesis was used. Stapedius tendon movement was routinely tested before and after surgery by stimulating the facial nerve with the Silverstein Facial Nerve Monitor/Stimulator (WR Medical Electronics; Stillwater, Minn.).

Results of outcomes questionnaire

Seventy-nine of the 124 questionnaires (64%) were returned (table 2). According to our analysis of the responses, there were no statistically significant postoperative differences between the group of patients whose tendon was transected and those whose tendon was preserved. However, there were nonstatistical trends noted in the responses to some of the questions.

On the other hand, we did observe certain statistically significant differences between pre- and postoperative hearing levels in both groups. For example, 91% of the tendon-sacrificed group and 94% of the tendon-preserved group said that before they underwent surgery, they had trouble hearing in a noisy location such as a restaurant. After surgery, those numbers decreased to 56 and 65%, respectively--a statistically significant difference (p[less than]0.001).

Moreover, 85 and 90% of the patients in the two groups, respectively, said surgery had improved their hearing over preoperative levels (p[less than]0.001). In the tendon-sacrificed group, 75% felt their hearing was greatly improved and 17% felt it was moderately improved. In the tendon-preserved group, these figures were 66 and 30%, respectively.

After surgery, 53% of the tendon-sacrificed group and 54% of the tendon-preserved group suffered noise intolerance, which diminished over time (p[less than]0.01). Before surgery, only 21 and 18%, respectively, said they had been intolerant to noise.

A nonstatistical trend indicated that the group whose tendon was preserved recovered more rapidly than did the group whose tendon was sacrificed (p[less than]0.10). We believe that the difference would have reached statistical significance had we studied a larger group.

Our clinical impression is that when the stapedius tendon was preserved, the patients did not appear to experience as much noise intolerance. This was demonstrated during the Rinne test 1 week postoperatively. After a successful stapes surgery in which the tendon is sacrificed, many patients have a strong withdrawal reaction to the 512 tuning fork. In the laser STAMP group, this reaction was not usually observed. Of the patients who had a period of noise intolerance postoperatively, almost none said they regretted that they had undergone the surgery (0% of the tendon-sacrificed group and 5% of the tendon-preserved group).

Twenty-seven patients reported that they had subsequently had surgery on their other ear as well. Of these, 73% of the tendon-sacrificed group and 87% of the tendon-preserved group experienced improvement in hearing; the difference between the two groups was statistically significant (p[less than]0.05). However, there was a nonstatistical trend showing that fewer patients felt their hearing was greatly improved after second-ear surgery (57 and 43%, respectively) compared with after first-ear surgery (66 and 75%, respectively; p[less than]0.20). Noise intolerance was less common after second-ear surgery (35 and 25%, respectively) than after first-ear surgery (54 and 53%, respectively; p[less than]0.0l).

Our questionnaire also included six quality-of-life questions taken from the 36-item short-form health survey. [12]

Responses to these questions did not demonstrate any statistically significant differences between the two groups.

Results of audiometric testing

Hearing results for the two groups are shown in table 3. There were no statistically significant differences in pure-tone and discrimination scores between the two groups. Only 8 patients (28%) in the tendon-preserved group demonstrated a stapedial reflex at an average of 6 months postoperatively (range: 1-15 mo). This was disappointing because most of the stapedius tendons responded to electrical stimulation of the facial nerve during surgery. The results of word and sentence discrimination tests are shown in table 4. The uncomfortable-loudness level test did not show any difference between groups. Nor was there any statistically significant difference between the unoperated and operated ears. Too few patients were tested preoperatively to validate a comparison of within-group changes in pre- and postoperative data.

Discussion

The results of this extensive questionnaire indicate that patients are pleased with the improvement in their hearing following stapes surgery. Opening the labyrinth in stapes surgery appears to make the ear more sensitive to loud noise for a period of time postoperatively, but the intolerance diminishes over time. Although there was no statistically significant difference between the patients whose tendon was sacrificed and those whose tendon was preserved, there was a nonstatistical trend showing that noise intolerance diminished more quickly in the tendon-pre-served group and that these patients reported having less trouble hearing in noisy environments. It is possible that patients experience hyperacusis because their hearing is so suddenly improved. Patients may have less hyperacusis after the laser STAMP procedure because there is no prosthesis in the vestibule that could excessively move the perilymph or because the hearing gain may be more gradual. Whatever the case, most patients said that transient h yperacusis would not deter them from undergoing stapes surgery. Finally, most patients reported improvement in hearing in noise following stapes surgery.

The results of second-ear surgery were not as dramatic, although patients did report a statistically significant improvement in noise tolerance. This might be explained by the fact that these patients could have become accustomed to loud noise after the first surgery.

Objective audiometric testing showed that closure of the air-bone gap was similar regardless of whether the stapes was sacrificed or preserved. Only 28% of patients with a preserved tendon demonstrated a stapedial reflex at the 6-month postoperative testing. This was surprising because the stapedius tendon contraction was demonstrated by electrical testing of the facial nerve at the conclusion of surgery. It appeared that the stapes reflex could return months after surgery. We plan to test these patients again after 1 year and have them complete the questionnaire again.

Causse reported that 75% of patients had a stapedial reflex when tested 1 year after stapedius tendon reconstruction. [13] Perhaps more of our patients will demonstrate a stapedial reflex when tested at our 1-year followup. In the group whose tendon was preserved, we could not demonstrate improved hearing when testing the patient while masking the same ear with noise.

Colletti found that patients heard better in noise when the stapedius tendon was preserved. [8] Our study does not provide statistically significant evidence that these patients do indeed hear better in noise or that they can tolerate noise better. Subjectively, there was no statistically significant difference between the two groups in our series. However, there were nonstatistical trends that indicated there might be better noise tolerance and better hearing in noisy environments when the stapedius tendon is preserved.

There are practical reasons for preserving the stapedius tendon when it can be done so without jeopardizing the exposure or the outcome. One reason is that it stabilizes the incus during prosthesis insertion, thus reducing the chance of accidentally dislocating the incus. Also, preservation helps maintain the blood supply to the lenticular part of the incus, which may reduce postoperative incus necrosis.

One possible disadvantage is that a brisk stapedius tendon reflex could dislodge the prosthesis. To guard against this, we stimulate the stapedius tendon with the nerve stimulator at the end of the procedure to ensure that the piston does not move into the vestibule or pull out of the oval window. Also, it is possible that repeated contractions could loosen the crimped wire or even possibly cause a sawing motion that could erode the incus. We minimize this risk by using the Causse Teflon prosthesis with a 1 mm width to the loop. Causse has not reported any incidence of this problem. A third possible disadvantage to preserving the tendon is the reduction in exposure of the footplate in certain cases. In such a circumstance, the stapedius tendon should be sacrificed. If an attempt is made to preserve the tendon in this case, the procedure may take longer to perform. The surgeon should ensure that the neck of the stapes does not touch or lie close to the promontory. In this case, the laser should be used to rem ove more of the neck of the stapes.

Theoretical reasons for preserving the stapedius tendon include the possibility of reducing the chance of barotrauma and acoustic trauma and improving the hearing in noisy environments. There may also be other unknown benefits. Even though we cannot prove statistically that tendon preservation results in any better hearing, we do believe that the tendon should be preserved whenever possible, as long as doing so does not compromise the surgical exposure or outcome.

From the Ear Research Foundation, Sarasota, Fla. (Dr. Silverstein, Dr. Deems, Dr. Rosenberg, Ms. Crosby), the Department of Otolaryngology--Head and Neck Surgery, University of Pennsylvania, Philadelphia (Dr. Kwiatkowski), and the Boone (N.C.) Regional Ear, Nose & Throat Association (Dr. Hester).

Reprint requests: Herbert Silverstein, MD, Ear Research Foundation, 1901 Floyd St., Sarasota, FL 34239. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

This study was supported in part by the Ear Research Foundation of Sarasota, Fla.

References

(1.) Perkins RC. Laser stepedotomy [sic] for otosclerosis. Laryngoscope 1980;90:228-40.

(2.) McGee TM. The argon laser in surgery for chronic ear disease and otoscierosis. Laryngoscope 1983:93:1177-82.

(3.) Silverstein H. Laser stapedotomy minus prosthesis (laser STAMP): A minimally invasive procedure. Am J Otol 1998;19:277-82.

(4.) Silverstein H, Hester TO, Rosenberg S. Preservation of the stapedius tendon in laser stapes surgery. Presented at the Southern Section Meeting of the Triologic Society, Lake Buena Vista, Fla., Jan. 16, 1998.

(5.) Marquette J. Le syndrome de surdite du a une deficience de la prothese stapedienne: Comptesrendus du Congres de la Societe Francaise d'oto-rhino-laryngologie 1965:151-60.

(6.) Girgis IH. Preservation of the stapedius tendon in stapes surgery. J Laryngol Otol 1966;80:733-42.

(7.) Farrior JB. Stapes surgery: Pathologic indications for bypass operation and vein graft. Trans Am Acad Ophthalmol Otolaryngol 1960:248-61.

(8.) Colletti V, Sittoni V, Fiorino FG. Stapedotomy with and without stapedius tendon preservation versus stapedectomy: Long-term results. Am J Otol 1988;9:136-41.

(9.) American National Standards Institute. (1996) American National Standard Specification for Audiometers. (ANSI S3.6-1996), New York: ANSI.

(10.) American National Standards Institute. (1991) Maximum Permissible Ambient Noise Levels for Audiometric Test Rooms. (ANSI 83.1-1991), New York: ANSI.

(11.) American National Standards Institute. (1987) American National Standard Specifications for Instruments to Measure Aural Acoustic Impedance and Admittance (Aural Acoustic Immittance). (ANSI S3.39-1989), New York: ANSI.

(12.) Ware JE Jr., Sherbourne CD. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992;30:473-83.

(13.) Causse JB. Stapedius tendon reconstruction. American Otological Society Meeting, Orlando, Fla., May 1996.

                   General characteristics of the patient
                                population
                        Age (yr)
Group # Pts Male Female   Mean   Range
  1    47    16    31      58    22-89
  2    32     4    28      59    26-79
           Questionnire responses (% of responses by patients in
                           group 1/group 2) [*]
BEFORE SURGERY
1. In a noisy situation like a restaurant
   or a cocktail party, do you feel that you
   had trouble hearing the person you
   were talking to ?
    a. Yes                                          91/94
    b. No                                             6/6
    c. All the time                                 28/23
    d. Frequently                                   21/23
    e. Some of the time                              14/6
    f. Rarely                                         2/0
    g. Never                                          0/0
    h. Uncertain                                      2/0
    i. Don't remember                                 0/0
2. When you used to sing, how did your
   own vice sound?
    a. Normal                                       43/25
    b. No                                             9/9
    c. Uncertain                                     7/18
    d. Don't know                                   39/46
3. Were your ears sensitive to loud noises?
    a. Yes                                          21/18
    b. No                                           67/65
    c. Uncertain                                      4/9
    d. Don't know                                     6/6
FIRST STAPES PROCEDURE
4. Was your hearing improved by surgery?
    a. Yes                                          85/90
    b. No                                           14/10
5. How much was your hearing improved?
    a. Slightly                                       7/3
    b. Moderately                                   17/30
    c. Greatly                                      75/66
6. Did loud noises bother your operated
   ear after surgery?
    a. Yes                                          53/54
    b. No                                           46/45
7. If yes, how long did loud noise
   bother your ear?
    a. Days                                         18/15
    b. Weeks                                        31/61
    c. Months                                       31/15
    d. Years                                         18/7
8. Do loud sounds affect the unoperated ear?
    a. Yes                                          18/33
    b. No                                           79/56
    If yes, to what degree?
    a. The same                                      2/15
    b. Differently                                   0/85
9. If differently, in which ear is the
   loud sound more annoying?
    a. Operated ear                                 75/70
    b. Unoperated ear                               25/30
10. Would you say that loud sounds bother
    your ears?
    a. Yes                                          46/45
    b. No                                           53/54
11. If loud noise bothers your ears, are
    you sorry you had the surgery?
    a. Yes                                           10/4
    b. No                                           89/96
AFTER SURGERY
12. In a noisy situation like a restaurant
    or a cocktail party, do you feel that
    you have trouble hearing the person
    you are talking to?
    a. Yes                                          56/65
    b. No                                           41/34
    c. All the time                                 19/14
    d. Frequently                                    23/4
    e. Some of the time                             26/42
    f. Rarely                                        7/19
    g. Never                                          0/0
    h. Uncertain                                      2/3
    i. Don't remember                                 0/0
13. Are your ears sensitive to loud noise?
    a. Yes                                          41/43
    b. No                                           53/34
    c. Not sure                                      0/18
    d. Don't know                                     4/3
14. Did the surgery help you tolerate noise better?
    a. Yes                                          30/30
    b. No                                           42/38
    c. Uncertain                                    27/30
15. If you also had surgery in the
    opposite ear, can you tell a difference
    between the ears regarding...
    15.1... hearing your own voice?
    a. Yes                                          35/25
    b. No                                           64/75
    15.2... sensitivity to noise?
    a. Yes                                          31/36
    b. No                                           68/64
    15.3...hearing in a noisy environment?
    a. Yes                                          37/54
    b. No                                           62/46
SECOND STAPES PROCEDURE, IF PERFORMED
16. Was your hearing improved by surgery?
    a. Yes                                            73/87
    b. No                                             26/13
17. How much was your hearing improved?
    a. Slightly                                        21/0
    b. Moderately                                     21/57
    c. Greatly                                        57/43
18. Did loud noise bother your ear after surgery?
    a. Yes                                            35/25
    b. No                                             64/75
19. If yes, how long did loud noise bother your ear?
    a. Days                                            33/0
    b. Weeks                                         33/100
    c. Months                                          16/0
    d. Years                                           16/0
20. If loud noise bothers your ears, are you
    sorry you had the surgery?
    a. Yes                                             9/20
    b. No                                             90/80
IF BOTH EARS WERE OPERATED ON
21. Which ear reacts to noise better?
    a. The first ear                                  45/16
    b. The second ear                                  0/16
    c. Both the same                                  54/66
22. Does sound appear more natural in one ear?
    a. Yes                                            53/25
    b. No                                             46/75
23. If yes, which ear?
    a. First                                         66/100
    b. Second                                          33/0
24. Are you happy with your hearing?
    a. First ear
       Yes                                            68/75
       No                                              25/8
    b. Second ear
       Yes                                              6/0
       No                                               0/0
    c. Both ears
       Yes                                             0/16
       No                                               0/8

(*.)Responses are percentages of answers given by patients in the two groups (group 1/group 2). Group 1 is comprised of patients whose stapedius tendon was sacrificed and group 2 is comprised of patients whose stapedius tendon was preserved.

                  Pre- and postoperative hearing data [*]
Air-bone               Speech               Air-bone
gap (dB)          discrimination(%)      gap closure (dB)
 Group   Pre Post        Pre        Post [less than]10  11-15 16-20
   1      30  8          91          89        37         6     1
   2      21  6          90          91        27         4     1
Air-bone
gap (dB)
 Group   [greater than]21
   1            3
   2            0
(*.)Standard audiometric testing results (mean values)
pre- and postoperatively in the twogroups.
         Discrimination in noise and uncomfortable-level values[*]
       NU6 [+]                     CID [ss]                     UCL [n]
       Pre            Post         Pre             Post         Pre
Group Ipsi     Contra Ipsi Contra Ipsi      Contra Ipsi Contra Ipsi
  1     64       62     64   82     94        94     96   97     95
  2     85       71     67   68     93        99     95   93    102
             Post
Group Contra Ipsi Contra
  1    100     89   96
  2     98     96   95

(*.)Results of noise discrimination and uncomfortable-levels testing pre- and postoperatively for both groups (mean values).

(+.)Northwestern University list of 25 words.

(ss.)10 Central Institute for the Deaf "everyday sentences" (Cochlear Corp. list 3, 4 or 5).

(n.)Sppech uncomfortable levels.