Total Stapedectomy

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Chapter 21 Total Stapedectomy

Howard P. House, Jed A. Kwartler

The goal of stapes surgery is to re-establish sound transmission through an ossicular chain stiffened because of otosclerosis. Various techniques have been used to accomplish this goal, including stapes mobilization, fragmentation, small fenestration, and partial and total stapes footplate removal.

The history of surgery for otosclerosis began in the latter part of the 19th century. A group of pioneering surgeons, including Kessel,1 Boucheron,2 Miot,3 Faraci,4 and Passow,5 began to mobilize the stapes. At about this time, Jack6 reported on a series of cases in which he removed the stapes entirely. The unacceptably high rate of inner ear injury and infection led to the abandonment of stapes surgery. As stated by Goodhill,7 “it was probably Siebenmann8 along with Moure9 who closed the door on further stapes surgery at the turn of the century.”

Surgery for otosclerosis was reactivated in 1923, when Holmgren10 bypassed the stapes area by creating a fenestra in the horizontal canal to stimulate inner ear fluids in response to sound, and the fenestration operation was reborn. In 1937, Sourdille11 presented a series of fenestration cases before the New York Academy of Medicine. In 1938, Lempert12 introduced his unique one-stage fenestration technique using his endaural approach and a dental drill to create the fenestra. Surgeons throughout the world clamored to learn his technique, which became the standard. Lempert will forever be known as the father of otosclerosis surgery.

In 1952, Rosen13 reintroduced stapes mobilization for otosclerosis. For a brief time, this technique was widely used and threatened to replace the Lempert procedure. It was soon realized, however, that refixation of the footplate often occurred. Shea14 introduced his technique of total stapedectomy. After removing the total stapes, he covered the oval window with a vein graft and introduced an artificial stapes made of polytef (Teflon) by Treace to make the connection with the incus. This reactivation of stapedectomy by Shea replaced Lempert’s fenestration procedure and Rosen’s mobilization operation, and, with modification, is now used universally throughout the world. We are greatly indebted to Shea for his tremendous contribution to otosclerosis surgery.

PATIENT COUNSELING

All patients should be told that even though their hearing loss is hereditary, their children or grandchildren will not necessarily have a similar problem. They should be assured they are not going to become totally deaf. The mechanics of the hearing loss should also be explained in detail, preferably by use of a suitable illustration.

Patients who are suitable for stapes surgery should be told that they have the option of wearing hearing aids, and if there is any doubt about the decision to have surgery, they should be encouraged to have a trial period with hearing aids unless they are already wearing them. The expected hearing result and all possible risks, such as further or total hearing loss, taste disturbance, dizziness, the effect on tinnitus (if present), and the very remote possibility of a partial or total facial paralysis, should be clearly understood. Hearing improvement is in direct proportion to the preoperative bone conduction level, and the patient must understand the degree of improvement to be expected.

SELECTION OF PATIENTS FOR STAPES SURGERY

All patients who are suitable for stapes surgery should be thoroughly informed of the advantages and the possible complications of the operation. For some patients, serviceable hearing can be restored with no need for a hearing aid. In others, the hearing can be improved so that they may need a hearing aid only for distant conversation. In still other patients, the hearing can be improved, and they may be able to convert their postauricular aid to an all-in-the-ear hearing aid or from an all-in-the-ear aid to an intracanal aid.

Occasionally, patients have a totally blank audiogram and are still suitable for stapes surgery. This situation occurs when the bone conduction level exceeds the capability of the audiometer. There may be a 75 or 80 dB bone conduction level, but a 40 to 50 dB air-bone gap. Typically, when the patient is initially evaluated, he or she is hearing surprisingly well with a powerful hearing aid and possesses excellent speech quality. On examination, one may note a positive Schwartze’s sign, but the 512 Hz tuning fork is not helpful. After surgery, these patients are grateful because they can now wear less powerful hearing aids with fewer feedback problems.

Indications for Stapes Surgery

The patient should understand the details of the operation, including the operative procedure itself, and all admission and discharge procedures. The following principles also apply:

1. The patient should be in reasonably good health, especially if general anesthesia is contemplated.
2. The age of the patient is not a factor in the decision to perform surgery. The youngest in our series was 7 years old, and the oldest was 98.
3. The poorer hearing ear, based on the patient’s statement and not on the audiogram, should be chosen for surgery. In children, the poorer hearing ear should be operated on so that the hearing aid can be eliminated before they enter school. Surgery for the second ear should be delayed until they are old enough to make their own decision.
4. Tuning forks should be used to confirm the audiometric findings. If bone conduction is heard louder than air conduction with a 512 or a 1024 Hz tuning fork, with proper masking of the better hearing ear, the individual is a suitable candidate for surgery. If one reverses the 2048 Hz fork, he or she is an excellent candidate. The minimum air-bone gap should be 15 dB, as averaged in speech frequencies.
5. Speech discrimination is not a major factor in determining stapes suitability. If the patient understands sentences and answers questions correctly using a speaking tube while masking the opposite ear with a Bárány apparatus, he or she is suitable, provided that the earlier criteria are met. The improvement the patient receives with a cochlear implant substantiates the value of any sound that helps patients hear and react better to their environment.
6. Indications for stapes surgery are essentially the same whether the hearing loss is unilateral or bilateral. Surgery in the opposite ear can occur 6 months later, provided that it is then the poorer hearing ear.

Contraindications of Stapes Surgery

Stapes surgery is contraindicated in patients (1) in poor physical health; (2) with a current balance problem, such as active Meniere’s disease or a fluctuating type of hearing loss; (3) with pre-existing tympanic membrane perforation; (4) with active external or middle ear infection; and (5) with an inadequate air-bone gap confirmed by an audiogram and the 512 Hz tuning fork.

SURGICAL TECHNIQUE

Step 1

Stapes surgery may be performed with a local or a general anesthetic. We prefer local anesthesia with adequate sedation that may be supplemented during the procedure with intravenous midazolam (Versed) or diazepam (Valium), if necessary. We prefer local anesthesia because there is less bleeding, and the surgeon is alerted if any vertigo occurs while working on the footplate, inserting the prosthesis, or removing the prosthesis, in a revision case.

Step 2

During surgery, the patient’s vital signs are monitored by electrocardiography, blood pressure, and oxygen saturation. The auricle and the surrounding area are cleaned with povidone-iodine (Betadine) solution, and plastic drapes and folded towels are applied. A final head drape with an opening exposing the ear is placed over the head and rested on a metal support to help prevent the feeling of claustrophobia.

Step 3

The operating table is placed slightly in Trendelenburg’s position and rotated toward the surgeon so that he or she can see directly down the ear canal from the sitting position.

Step 4

The ear canal is washed with warm saline solution to remove the povidone-iodine, and local anesthesia containing 2% lidocaine in epinephrine 1:100,000 is infiltrated. The initial injections are made with a 30 gauge needle around the periphery of the entrance to the ear canal. Approximately 2.5 to 3 mL of this solution is injected, and 1 or 2 drops are placed in the vascular strip just external to the tympanic membrane. This helps reduce the bleeding at the time of the incision. The tissue to be used, whether vein, fascia, perichondrium, or fat, may be obtained before or after the canal surgery is started.

Several sizes of oval and round specula should be on the tray, and the largest one that can be seated into the canal is used. The shafts of the instruments entering the speculum are in firm contact with the middle finger, which is stabilized against the speculum, and the speculum is stabilized by the other fingers against the head. A fixed speculum holder is not used. The advantage of not using a fixed speculum holder is flexibility of the speculum for viewing purposes and for allowing the patient to move his or her head, if desired. The specula and all instruments should be plain metal because black specula and instruments absorb much-needed light. The shafts of the needles and hooks should be malleable so that they can be bent slightly to reach difficult areas.

The inferior and superior vertical incisions are made at the 6:30 and 11:30 o’clock positions (Fig. 21-1). The point of the sickle knife is started 1 mm from the edge of the tympanic membrane to prevent a possible tear. It is extended externally approximately 8 mm, and this distance can be confirmed when the curve of the incision knife strikes the edge of the properly inserted speculum. If one extends the incisions further externally, the skin becomes thicker, and more bleeding occurs. Several sweeps are made to ensure that one cuts through the periosteum.

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FIGURE 21-1 Inferior and superior vertical incisions.

FIGURE 21-2. Elevating the skin flap.

FIGURE 21-3. Middle ear exposure.

FIGURE 21-4. Separating the incudostapedial joint.

The horizontal incision begins by elevation of the skin from the depth of the suture indentation, and continues inferiorly in short increments toward the inferior vertical incision to avoid tearing of the skin toward the eardrum. Several clean sweeps of the knife are again made to ensure that the periosteum that connects to the inferior vertical incision has been cut through. A similar superior incision is made in increments halfway to the superior vertical incision. Several sweeps are made on this partially completed incision. The knife is inserted beneath the remaining skin to elevate it. Scissors are used to connect with the end of the superior vertical incision. Scissors crush the vessels in the vascular strip and help reduce the bleeding.

After these incisions, a broad separator is used to elevate the skin flap in a uniform manner toward the eardrum. Considerable pressure is applied on the instrument, especially inferiorly, to stay under the periosteum until it enters the middle ear area posterior to the ligament.

A curved Rosen needle is used superiorly to elevate the eardrum and identify the position of the chorda tympani nerve (Fig. 21-2). When the nerve is identified, the needle is inserted superiorly to the nerve and carried forward to contact the malleus. This action provides the superior exposure. The needle is used inferior to the chorda tympani to identify the beginning of the tympanic membrane ligament. An elevator is used to lift the ligament inferiorly and to identify the round window. At this point, a cotton ball soaked in the lidocaine/epinephrine solution is placed on the raw surface of the skin flap to lessen the bleeding for a moment. The entire skin flap is elevated anteriorly, and a few drops of lidocaine/epinephrine are dropped onto the mucosa of the middle ear for anesthesia and to control any mucosal bleeding later as work is done in the stapes area.

To visualize the footplate, bone of the posterior scutum is removed. At the upper limit of exposure superiorly, one should observe the lower half of the transverse portion of the fallopian canal (Fig. 21-3). If one can see the beginning of the curve of the body of the incus, a subsequent retraction pocket may develop. The posterior exposure is limited to observation of the stapedial tendon and the attachment of the posterior crus of the stapes to the footplate. If more bone is removed, a posterior retraction pocket may develop. This exposure is usually done with curettes, but a diamond burr may be necessary to expose the posterior portion of the chorda tympani. On completion of this exposure, a square area is created posterosuperiorly. When the curette or the burr is used, the patient under local anesthesia should be forewarned of the noise that is created so there is no surprise to the patient.

If the footplate area appears to be thin, a sharp needle is used to make a small perforating hole in the thinnest area. This small hole later provides an opening in which an obtuse hook can be inserted if the footplate is inadvertently mobilized at the time the crura are fractured toward the promontory.

A small, round right angle knife is used now to separate the incudostapedial joint (Fig. 21-4). The intact stapedial tendon helps prevent an inadvertent mobilization from occurring. In this manipulation, a mild pressure and “jiggling” of the knife blade back and forth is used because if strong direct pressure is applied, dislocation of the incus may occur when the joint is suddenly separated. The necessary limits of exposure are the round window inferiorly, the lower half of the fallopian canal superiorly, the stapedial tendon pyramidal eminence and posterior crus posteriorly, and the malleus anteriorly (Fig. 21-5).

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FIGURE 21-5 Adequate exposure.

FIGURE 21-6. Fracturing the crura from footplate.

FIGURE 21-7. Measuring for prosthesis.

FIGURE 21-8. Removing the footplate.

FIGURE 21-9. Placing tissue over the oval window.

FIGURE 21-10. Placing the prosthesis.

The malleus is now checked to determine its mobility. One in 200 patients has a fixed malleus. If fixed, alternative techniques must be used (described later). The stapedial tendon is cut; then the patient is forewarned that a loud sound is forthcoming. The Rosen mobilizing needle is placed on the superior side of the stapes arch near the neck, and the superstructure is sharply fractured toward the promontory and removed (Fig. 21-6).

The distance from the top of the incus to the thin, fixed footplate is measured (Fig. 21-7). Some surgeons measure from the inferior surface of the incus, and the prosthesis length is made accordingly. The prosthesis length should be checked before it is inserted. The measurement from the outer portion of the incus to the footplate is usually 4.5 mm, but may vary from 3.5 to 5.5 mm.

The membrane is left intact over the footplate because it helps prevent bony chips from dropping into the vestibule. Obtuse, right angle hooks and finally the Hough hoe is used to remove the posterior and then the anterior portion of the footplate, effecting a total removal (Fig. 21-8). Great caution must be used to avoid suction of the perilymph when blood is suctioned from around the oval window. During footplate removal, bone chips or blood entering into the vestibule is left undisturbed.

The previously prepared tissue of choice, measuring about 5 × 5 mm, is grasped with a nonserrated alligator forceps and slipped over the oval window so that it covers all the edges and is positioned superiorly over a portion of the fallopian canal (Fig. 21-9). The prosthesis is inserted with a nonserrated forceps into the center area of the oval window and over the incus (Fig. 21-10). A crimper is used to close the loop on the incus, and the wire is moved toward the lenticular process. The skin flap is then placed back in its normal position, and a small gauze wick is inserted into the hypotympanic area. A cotton pledget is placed over the opening of the external ear canal, and a Band-Aid or two holds the cotton in position, completing the procedure.

In our experience, whether one totally or partially removes the footplate or uses the small fenestra technique, or whether one uses the diamond burr or the laser to create the small fenestra, the end result is quite similar. More surgeons are using the small fenestra technique, and the postsurgery imbalance is less noticeable because perilymph disturbance is minimal. It is not the technique, the instruments, or a particular prosthesis that leads to a successful result, but rather the hands and mind behind the instruments. If one is closing the air-bone gap in 90% of the cases and encountering no more than a 1% severe sensorineural loss, one should stay with that technique.

POSTOPERATIVE CARE

Some patients may have dizziness for a few hours after surgery. They are cautioned not to blow their nose hard. If patients sneeze, they should do so with their mouth open, and they should avoid excessive straining for 2 weeks. If operated on in the morning, the patient usually can go home that night and remove the Band-Aid, cotton, and gauze wick the following morning. Patients are allowed to travel by air 3 days after surgery and are instructed to use a nose spray and swallow frequently on descent.

Most patients hear immediately after surgery, but their hearing level may decrease a few hours later. Barring complications, patients should have their first hearing test 3 weeks after surgery, at which time most have recovered their hearing. In others, the hearing improves over the next 3 months. The hearing they have at this time is what they will keep. We do not do revision surgery on any patient until 4 months have passed. All patients are routinely placed on a sodium fluoride and calcium carbonate supplement (Florical), 8 mg three times a day, and are followed up routinely on an annual basis.

INTRAOPERATIVE PITFALLS

Chorda Tympani Nerve

During the procedure, the chorda tympani nerve may be enlarged, or may be in a position to interfere with proper visualization of the stapes area (Fig. 21-11). The chorda tympani may be gently moved superiorly and inferiorly. If it is stretched to the point of a partial tear, it should be severed rather than left partially functioning—the patient has less taste disturbance than when a partially functioning chorda is left intact. One should not sever the chorda if the opposite ear is operated on because a dry mouth and a severe taste disturbance may result.

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FIGURE 21-11 A and B, Superior retraction of chorda tympani for visualization.

FIGURE 21-12. A-F, Incus replacement prosthesis.

Eardrum Perforation

If a small perforation of the tympanic membrane occurs during surgery, it often heals if the edges are placed together. If a larger tear occurs, tissue is used with an underlay technique.

Malleus Fixation

If the malleus is fixed, and the stapes is mobile, further stapes surgery is abandoned. The incudostapedial joint is carefully separated, and the incus is removed (Fig. 21-12). The head and neck of the malleus are exposed further anteriorly, and the Lempert snipper is used to sever the neck. Fixation usually results from tendon ossification, and tapping with a small chisel on the head of the malleus frees it, enabling removal. Continuity between the mobile stapes and the eardrum may be re-established by reconstruction.

If the stapes is also fixed, an incus replacement prosthesis is used. Incisions are made to separate the periosteum from the middle one third of the malleus, and an incus replacement wire prosthesis is inserted through the opening. A right angle hook is used to rotate the loop portion and placed on the surface of the footplate to determine if the length is proper. The usual length is 5.5 mm. After this step, the loop is elevated away from the footplate, and the head and neck of the malleus are removed. The footplate is removed, and the loop of the prosthesis is placed into the oval window. The shaft of the prosthesis is grasped with a nonserrated alligator forceps to stabilize it, and with the right hand, it is tightened on the malleus by use of a right angle hook. Fat or absorbable gelatin sponge (Gelfoam) centers the loop in the oval window. Other types of prostheses, such as clamp-on plastic pistons, are available, and for some surgeons, these are more easily attached and inserted into the oval window. Another option is to use a total ossicular replacement prosthesis.

Facial Nerve Abnormalities

The facial nerve is often dehiscent in its tympanic segment, but the dehiscence is rarely seen because it often occurs on its undersurface. If the dehiscence is extensive, a prolapse covering half of the footplate area may occur. In this case, the facial nerve may be carefully elevated superiorly, and an opening may be made in the footplate for insertion of the prosthesis. If the shaft of the prosthesis needs to be bent, it usually does not provide a satisfactory hearing result. If the prosthesis rubs on the prolapsed facial nerve, it does not disturb facial nerve function. A marked prolapse covering the entire oval window requires a prosthesis from the malleus. In these cases, the incus is removed, and the facial nerve is moved slightly so that the inferior part of the footplate can be visualized and then fragmented for insertion of the incus replacement prosthesis with the loop into the fragmented area.

Floating Footplate

The most difficult complication in otosclerosis surgery is the solid floating footplate; this requires the most complicated and difficult procedure encountered in stapes surgery and should be managed only by highly experienced surgeons. In this problem, a small cutting burr is used posteroinferiorly on the promontory “side” of the oval window to gain room. The drilling stops 1 mm from the floating footplate. Straight and obtuse needles are used to enter the vestibule along the side of, but at no time touching even the edge of, the floating footplate.

A right angle hook is inserted into the opening and then rotated to the undersurface of the footplate. It is elevated outward and anteriorly toward the fallopian canal. Blood adhesiveness allows the plate to remain there after the hook is removed and reinserted under the edge of the footplate to slip it up and over the fallopian canal, where it can be grasped. Only then can the surgeon take his or her first breath with a sigh of relief!

Solid or Obliterated Footplate

By observation, the surgeon cannot determine whether the footplate is minimally fixed at the edges or is obliterated (Fig. 21-13). In each instance, it is necessary to use a cutting burr with a gentle paintbrush-type stroking motion anteroposteriorly. If the slightest give is felt with the drill, minimal fixation and a floating footplate exist. Perilymph escape is noted around the edges. The technique to be used is the same as for the solid floating plate.

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FIGURE 21-13 Minimally fixed solid footplate.

Obliterated Footplate

With an obliterated footplate, a cutting burr is used anteroposteriorly and around the edges to develop a thin blue area. The burr is used to enlarge the opening sufficiently to cover the area with a graft and to insert the prosthesis of choice. The edges are always jagged because there is no demarcation between the attachment of the footplate to the surrounding bone as there is in the solid footplate. These patients respond well to the small fenestra, the subtotal footplate, or the total removal technique. The floating footplate does not occur in obliterated cases.

Round Window Closure Owing to Otosclerosis

A round window closure owing to otosclerosis is rare and is best left undisturbed. In these cases, there is always a fibrous band leading to the round window that is apparently sufficient to produce the necessary relationship between the oval window and the round window. Complete drilling out of the round window has not given the desired result and may make the hearing worse.

Perilymph Gusher

When the cochlear aqueduct is widely patent, it may result in an excessive perilymph flow after the surgeon perforates the footplate. If it is a massive gusher (e.g., like a broken fireplug), one should not proceed with the removal of the stapes. It would be best to scrape the membrane of the footplate and the surrounding oval window area with suction in one hand, followed by the placement of small pieces of fascia or perichondrium in the arch of the stapes to help hold them in place. On one such occasion, we proceeded to remove the stapes and its footplate. The tissue placed over the oval window floated away, and it needed to be held in place with a suction tip in one hand until the prosthesis was inserted onto the incus. We packed the middle ear solid with Gelfoam and replaced the flap, only to note the flap being elevated by the flow of perilymph. The ear canal was tightly packed to hold the flap in place, and the patient was elevated to a sitting position. The mastoid dressing was changed repeatedly until the flow stopped.

Intraoperative Vertigo

When patients are under local anesthesia, their response to sudden vertigo is immediately noted by the operating surgeon. Vertigo may occur more often in revision procedures if the covering tissue membrane is inserted too deeply into the vestibule, or if the prosthesis is too long. If the cause is tissue, it should be carefully removed and replaced. If the prosthesis is too long, it should likewise be removed and replaced with a shorter one. In revision, the incidence of further sensorineural loss is slightly more common than in a primary case.

Deep Oval Window

In some cases, the oval window niche is very narrow and very deep. If this condition results from otosclerotic encroachment on the sides of the oval window, it can be enlarged by use of a cutting burr. If there is another cause, a broad posterior crus located in the deep narrow niche may be difficult to fracture from the footplate. In this instance, after a small perforating hole has been made in the footplate, a tiny cutting burr or a laser may be used to cut through the posterior crus, making removal of the superstructure of the stapes possible.

SUMMARY

Training surgeons is difficult because of the scarcity of suitable otosclerotic patients, and it is difficult for residents to obtain sufficient experience to ensure good hearing results in their patients. If a surgeon is obtaining the results being reported in the literature—90% closure of the air-bone gap within 10 dB and no more than 1% further sensorineural loss—there is no need to change technique. It is not the instruments or technique that ensures success, but rather the minds and the hands in control of the instruments.

AUTHORS’ NOTE

Most patients with otosclerosis who opt for surgery today usually undergo a small fenestra-type procedure, with the use of either a microdrill or a laser. The evolutionary changes in stapes surgery have primarily occurred in the prosthesis itself, with the development of new self-crimping materials, and in the drill and laser instrumentation. The general concepts of stapes surgery still stand, however, as they did since the late 1950s.

This chapter serves as a reminder of those general concepts and the importance of anticipating, and then dealing with, the unexpected in surgery, such as when the footplate mobilizes or fractures and the whole thing comes out. Knowing the steps to completing a total stapedectomy and having the confidence that the results can be consistently as good as a small fenestra approach are requirements for anyone contemplating performing stapes surgery.

REFERENCES

1. Kessel J. Uber das Mobilisieren des Steigbugels durch Ausschneiden des Trommelfelles, Hammers und Amboss bei undurchgagikeit der Tuba. Arch Ohrenheilkd. 1878;13:69-88.

2. Boucheron E. La mobilisation de l’etrier et son procede operatoire. Union Med Can. 1888;46:412-416.

3. Miot C. De la mobilisation de l’etrier. Rev Laryngol Otol Rhinol (Bord). 1890;10:49-54.

4. Faraci G. Importanza acustica e funzionale della mobilizzazione della staffa: Risultati di una nuova serie di operazioni. Arch Ital Otol Rinol Laringol. 1899;9:209-221.

5. Passow K.A. Operative anlegung einer offnung in die mediale paukenhohlenwand bei stapesankylose. Ver Dtsch Otol Ges Versamml. 1897;6:141.

6. Jack F.L. Remarkable improvement of the hearing by removal of the stapes. Trans Am Otol Soc. 1893;284:474-489.

7. Goodhill V. Stapes Surgery for Otosclerosis. New York: Paul B. Hoeber; 1961.

8. Siebenmann F. Traitement chirurgical de la sclerose otique. Cong Int Med Sec Otol. 1900;13:170.

9. Moure E.J. De la mobilisation de l’etrier. Rev Laryngol Otol Rhinol (Bord). 1880;7:225.

10. Holmgren G. Some experiences in surgery of otosclerosis. Acta Otolaryngol (Stockh). 1923;5:460.

11. Sourdille M. New technique in the surgical treatment of severe and progressive deafness from otosclerosis. Bull N Y Acad Med. 1937;13:673.

12. Lempert J. Improvement in hearing in cases of otosclerosis: A new, one-stage surgical technic. Arch Otolaryngol Head Neck Surg. 1938;28:42.

13. Rosen S. Restoration of hearing in otosclerosis by mobilization of the fixed stapedial footplate: An analysis of results. Laryngoscope. 1955;65:224-269.

14. Shea J.Jr. Fenestration of the oval window. Ann Otol Rhinol Laryngol. 1958;67:932-951.

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