Correction of Failures after Hinge-Like Stapedoplasty. 

Abstract:

INTRODUCTION

results in a hyperacusia and vestibulopathy, that is invalid for trades are connected to noisy conditions or with vestibular overloads and is especial for children. 
Attempts of many authors to restore the protective mechanism of middle ear with the help of preservation of a M.stapedius and its connection with a long process of an anvil, this mechanism is not regained, as a contraction of the M.stapedius causes only a shift of the caput stapedis and the prosthesis of the stapes in the direction of the traction of the M.stapedius, rather than to the direction of traction under an angle of 90o which is needed (Fig. 2). 

Our scientific development [Uliyanov Y.P 1997] have shown, that to restore the protective mechanism of the middle ear it is necessary to recover the "hinged mechanism" (C) at the posterior edge of the fenestra vestibuli (A), which would be similar to the natural one. This could be achieved only through making the prosthesis of the crus posterius in the shape of a "cross-bar" (spreader) (9) between the caput stapedis (1) and the posterior edge of the fenestra vestibuli (A), forming thereby a "hinged mechanism" (C) at the posterior edge of the fenestra vestibuli (Fig. 3),(Fig. 4)

This method was named as the "hinge-like" stapedoplasty (Patent of the USSR No 1792649). However, this method of stapedoplasty with a "spreader" (9) is connected with additional difficulties, as increased technical demands are placed on the otological surgeons performing this procedure and the operative time is longer. Therefore, we have developed a special complex prosthesis for the "hinge-like" stapedoplasty (Russian Federation's Patent No 016372), which permits a simultaneous recovery of the sound-conducting mechanism and the "spreader" mechanism (Fig. 5).

In placing this stapes prosthesis, all the surgeon has to perform is to put the caput stapedis ahead two superior projections of the prosthesis (10), between which the tendon of the M.stapedius is put. 
 However, more physiological for a recuperation of the "hinged mechanism" is use the crus posterius of the stapedis, which also it is possible is placed on the posterior edge of the fenestra vestibuli (Fig. 4), 
 

which we more often use too.
An experience with application of this method in 200 patients with otosclerosis has proved its efficiency. After going through this procedure,  patients were free from hyperacusis and vestibulopathy despite all kinds of strains. The tractor driver and the pilot could return to their previous work. Stable results after over ten years have confirmed the efficiency of this method, which has allowed us to apply the method also in children. However, in some patients the hearing ability has decreased in the conductive-like type within six months after surgery. This study has been conducted to examine this facts and to work out measures aimed at its preventing.

METHOD

The study included 300 patients after "hinge-like" stapedoplasty aged from four to 62 years, including 183 women (200 patients were operated upon before 1996 and 100 during the recent (subsequent) years). The crus posterius of the stapes was used as a "spreader" in 210 cases and at other patients instead of the crus posterius of stapes was used  teflon "spreaders". An analysis was carried out to establish the mechanism of the postoperative disturbance of the sound conduction with the resulting impaired hearing in them. Therefore, the more successful variant of "hinge-like" stapedoplasty was developed, which allows to prevent the revealed deterioration of hearing in the postoperative period at these patients. 

RESULT

Within six months after surgery hearing was impaired in 82 (27,3%) patients. Because of impaired sound conduction, hearing was impaired in 76 (25,3%) patients from this group where the crus posterius of the stapes was used as a "spreader". In 71 cases, a re-operation revealed immobility of the sound conduction system brought about by adhesion of the crus posterius of the stapes with the promontory of cochlea . This adhesion was caused by the pronounced form of the promontory wall, with resulting contact with the crus posterius of the stapes (Fig. 6 ).
 

The patients' age ranged from 20 to 56 years, with 51 women among them. In the first 24 cases, the crus posterius of the stapes was removed and replaced with the teflon "spreader" (Fig. 3 ). In subsequent 47 cases we tried to keep the crus posterius of the stapes for a restorations of the "hinged mechanism " (Fig. 4). But for prevention of contact (and development synechiaes) between the crus posterius of stapes and promontory we specially made the crus posterius is more thin.
 Its thinning down was performed at the side of the promontory (the crus posterius of the stapes was split and its half at the side of the promontory cut away). To cut a half of the crus posterius of the stapes (Fig. 7 ),
 
 

it was dragged to the promontory upside-down, which enabled splitting of the same with the acute microchisel with consequent cutting of its half near the caput stapedis. This variant of "hinge-like" stapedoplasty was successfully executed at re-operation at 36 patients with positive results on an extent more than 1,5   years, that is the sufficient proof of efficiency of a method, because the adhesion process in these cases develops per the first half of year only. 
In 11 cases, this method failed, as the whole of the crus posterius of the stapes was destroyed, so that the latter had to be replaced with the teflon complex prothesis (Fig. 5).
In subsequent operations, in case the fact of the crus posterius of the stapes leant to the promontory and was revealed to generate  the "hinge mechanism" near the posterior edge of the fenestra vestibuli, we began to split the crus posterius of the stapes with removing its half away, which has allowed us to avoid the risk of its consequent adhesion with the promontory (Fig. 8). 
 

CONCLUSION

1.  The main reason of impaired hearing after the ''hinge-like'' stapedoplasty is adhesion of the crus posterius of the stapes with the adjacent promontory -25,3%.
2.  In performing re-operation because of impaired hearing after the ''hinge-like'' stapedoplasty, in case the promontory is adhered to the crus posterius of the stapes, either the latter should be replaced with the teflon spreader or a half of the crus posterius of the stapes should be cut away at the side of the promontory, in order to avoid the risk of its recurrent adhesion to the promontory in the postoperative period.
3. In performing the ''hinge-like'' stapedoplasty, special attention should be paid to the fact of adjacency of the promontory to the crus posterius of the stapes. In down such cases, it is necessary either to thin the crus posterius of the stapes, or to replace it with the spreader prosthesis, to avoid the risk of its adhesion to the promontory in the postoperative period.
 

REFERENCES

[2]Uliyanov Y.P. . Stapedoplasty and stapedectomy with  ''hinge'' at the posterior edge of the fenestra ovalis. File from: ''Stapedoplasty and stapedectomy with teflon-piston''. The Master's thesis (Dissertation of the candidate) of medical sciences. Moscow,1967, 345 p. ( In Russian).

[3]Uliyanov Y.P. The method of  ''hinge-like'' stapedoplasty. From:
Stapedoplasty and stapedectomy for otosclerosis. By N.A.Preobrajensky, Î.Ê.Patakyna. Ìoscow. 1973, 133-134. ( In Russian).

[4]Uliyanov Y.P.  The Russian PATENT ¹ 1792649, on the invention under the application  ¹ 0910378 from 6 July 1964. Repair of the hinged mechanism of the stapes. The Bulletin of the Inventions and Opening Russian.

[5]Uliyanov Y.P. Repair of the hinged mechanism of the stapes. XYI - World Congress Of Otorhinolaryngology Head and Neck Surgery. (Sydney, Australia, 2-7 March, 1997), p.1077-1080.

[6]Uliyanov Y.P .Correction of Failures after Hinge-Like Stapedoplasty J.Otolaryngology-Head and Neck Surgery. 1999, V.121, N. 2,  p.202.

[7]Uliyanov Y.P.  The Russian PATENT ¹ 2118895, on the invention under the application  ¹ 96110084 (016372) from 27 May 1996. The device of the "hinged" stapedoplasty. The Bulletin of the Inventions and Opening Russian. ¹ 26; 20.09.1998. ( In Russian).