Stapedectomy Technique

Updated: Mar 03, 2016
  • Author: Rodney C Diaz, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
  • Print
Technique

Initial Approach

Once the patient is prepared and draped for the procedure, the operating microscope is brought into the field and used throughout the procedure. The povidone-iodine solution is irrigated out of the ear canal using warm saline and the tympanic membrane examined to ensure that there are no perforations.

The posterior canal incision is then created using a sickle knife or beaver blade.

If a standard posterior canal incision is made, it should be started at the 12 o’clock position about 3-4 mm from the annulus. This should then extend in a crescent from the 12 o’clock to the 6 o’clock position, extending to about 7-8 mm from the annulus along the posterior wall and swinging back toward the annulus to be within 3-4 mm at the 6 o’clock position. The flap should be slightly longer mid-flap than at either of the ends to ensure that the flap will reach the canal wall after some bone has been removed from the posterior scutum.

Other forms of incisions that can be used include the H flap, which involves a superior and inferior vertical incision at 12 o’clock and 6 o’clock and a connecting incision 7-8 mm lateral to the annulus. In the modified H flap, the inferior vertical incision starts 1 mm from the annulus and is curved, starting from the vertical incision 8 mm lateral to the annulus and curving superiorly to the 12 o’clock position. Several clean passes with the knife are used to ensure that the cuts have progressed through the periosteum to the bone.

The tympanomeatal flap is then elevated with a wide elevator in a uniform manner toward the tympanic membrane. Care must be taken not to tear the flap as it is elevated.

Once the annulus is reached, the fibrous annulus is elevated off the bony annulus using a fine blade or needle such as a tab dissector or a Rosen needle. This is elevated in the inferior aspect of the incision to avoid inadvertent injury to the chorda tympani as it exits the bone.

Once the middle ear mucosa is identified, the middle ear is entered using the Rosen needle. The fibrous annulus is then fully lifted off the underlying bony annulus using a flap elevator such as Gimmick or the Rosen needle. This allows identification of the position of the chorda tympani nerve. The needle is then inserted superior to the nerve in a similar manner and carried anteriorly until it contacts the malleus. With the superior and inferior exposures obtained, the tympanic membrane is then separated from the chorda tympani, allowing anterior elevation of the tympanomeatal flap. Any bleeding at this stage is controlled with topical epinephrine.

In order to expose the oval window and the stapes, bone from the posterior scutum must be removed. This is accomplished with either a stapes curette or drill until the entire oval window can be visualized. If the beginning of the curve of the incus is visible, it could lead to a subsequent retraction pocket developing here, which should be avoided. The exposure should provide a view of the attachment of the anterior and posterior crura to the footplate, as well as the stapedial tendon from the pyramidal process to its attachment on the stapes.

At this point, the stapes and the remaining ossicular chain should be palpated to ensure that the stapes is indeed fixed. Once confirmed, a small, round right-angle knife is used to separate the incudostapedial joint. The intact stapedial tendon provides some resistance that can help avoid an inadvertent stapes subluxation. Small sawing or jiggling motions should be used to separate the joint, as strong direct pressure can lead to a dislocation of the incus as the joint separates. Once the joint is separated, palpation of the incus and malleus should reveal good mobility.

The stapedius muscle tendon is then cut with scissors or the laser and any adhesions within the middle ear transected in order to completely free the stapes from any attachments. The stapes superstructure is then removed in any of numerous ways. Classically, a Rosen needle or other instrument is placed on the superior side of the stapes arch near the neck and then sharply fractured inferiorly to fracture the anterior and posterior crura simultaneously. Another approach is to use a laser to vaporize the posterior crus near its attachment to the footplate and then to down-fracture the anterior crus in a similar fashion. In either case, most of the stapes superstructure should be removed to allow unobstructed placement of the prosthesis.

The distance from the incus to the fixed footplate is then measured. Most surgeons measure from the outer aspect of the incus and size the prosthesis accordingly. In most cases, the length from the outer aspect of the incus to the footplate is 4.5 mm but may range from 3.5-5.5 mm.

Next:

Stapedectomy Versus Stapedotomy

The classic description of a stapedectomy from this point is to completely remove the posterior and anterior portions of the footplate, leaving the membrane below the footplate intact. This is accomplished with various instruments angled appropriately to allow removal of the bone with preservation of the underlying membrane. Suction in this area is undertaken with great care as not to remove perilymph from the vestibule during this portion of the procedure. The oval window is then covered with a previously prepared piece of fascia or other tissue of choice to allow placement of the prosthesis over this.

The more recent modification and more commonly performed procedure is stapedotomy. In this procedure, the entire footplate is not removed; instead, a fenestration is created in the footplate to allow placement of a prosthesis within this. This has the theoretical advantages of reducing the risk of perilymph fistula from removal of the footplate and avoiding sensorineural hearing loss due to excessive manipulation of the footplate during removal in a stapedectomy. Studies have shown equivalent results for both techniques, [15, 16] with excellent long-term results for stapedotomy, as well. [3]

Currently, stapedotomy is the treatment of choice for otosclerosis with stapes fixation, since it is both simpler and safer than stapedectomy.

With stapedotomy, once the stapes superstructure has been removed, a laser is used to create the fenestration in the footplate. This usually begins by focusing the laser on a vessel on the footplate in order to produce char that will allow the subsequent creation of a rosette of laser perforations. This initial step is necessary with the KTP or argon lasers, since the light is better absorbed by the hemoglobin pigment than the tissue of the footplate itself. The CO2 laser does not have the same requirement. The rosette is enlarged sufficiently to accommodate the prosthesis within the footplate. Perilymph that seeps through the fenestration can be removed carefully using a 24-gauge suction.

An alternative to using the laser for creating the fenestration is the microdrill. This has the benefit of developing a uniform fenestration; however, the noise created by this technique in a patient under local anesthesia is sometimes intolerable, and the patient should be warned of an impending loud noise so he or she is not startled.

Once the fenestration has been created and adequately sized, the distance from the incus to the footplate is measured and the prosthesis appropriately sized. Various prostheses types are available, ranging from the Richardson bucket handle prosthesis to the SMart nitinol-polytef piston. Regardless of the prosthesis used, it is used to reestablish continuity between the long process of the incus to the stapes footplate. Most of these use a hook that attaches over the incus with a piston that inserts into the fenestration. The SMart piston is crimped in place by the laser on the hook. Other devices are crimped using special instruments or a nonserrated alligator.

Once the prosthesis is in place, the mobility of the ossicular chain is tested. Adequate mobility is ensured, and there should be some perceptible movement of the round window noted when the chain is palpated. Once this is complete, small pieces of Gelfoam are placed around the prosthesis to ensure it remains in its proper place, and the tympanomeatal flap is laid back into position. Some surgeons use a Shaw disk to hold the flap in proper alignment. A cotton ball is placed in the conchal bowl, and a Band-Aid is placed over the cotton ball.

Previous