Operating Room Setup and Preparation

Stapedectomy surgery requires great finesse for good results. Thorough preoperative preparation results in smoother intraoperative execution and consistently good results. A surgical team that is familiar with the procedure and setup is of paramount importance. A scrub nurse who is knowledgeable about otologic instruments and can anticipate what is needed for the next step of the procedure is crucial. A microscope mounted closed circuit television camera with monitor allows the scrub nurse to see what the surgeon is doing and anticipate the next instrument that is needed. In a difficult case, with unfavorable anatomy or bleeding or both, the surgeon must have the right instrument in a short amount of time to complete the operation effectively. A scrub nurse who is not trained to assist in a stapes surgery is unable to perform adequately in these situations.

The anesthesiologist or local monitoring nurse is positioned at the foot of the table. The scrub nurse is positioned directly across the table from the surgeon. This positioning allows the nurse to hand instruments to both of the surgeon’s hands, greatly improving the efficiency. The microscope is positioned at the head of the table. Proper patient positioning can greatly facilitate the ease of this procedure. The patient’s head is turned away from the surgeon with the chin tucked toward the opposite shoulder. This maneuver aligns the external auditory canal with the view of the surgeon sitting in a neutral position. Failure to tuck the chin can result in the surgeon leaning over the patient’s chest and much less effective visualization of the field. The operating table is positioned in slight Trendelenburg. This head-down position counteracts the normal inferior angulation of the external auditory canal and results in improved visualization. Generally, the patient is positioned so the plane of the tympanic membrane is parallel with the plane of the floor in the operating room.

A support bar (Fig. 22-1) is attached to the operating table to keep the drapes off the patient’s face. By attaching the bar directly to the table, the bar moves in conjunction with the table. Using a floor-mounted device, such as a Mayo stand, does not allow the coordination of movement between the two items and can result in limitations of table movement. The operative site is prepared by surrounding the ear with a plastic drape (1030; 3M) that keeps the hair out of the operative field. The ear and a margin of the plastic drape are prepared with povidone-iodine (Betadine) solution, and the povidone-iodine solution is allowed to fill the ear canal. Intravenous midazolam (Versed) is used for sedation. This medication is given in 0.5 mg increments until the patient is sleepy and relaxed. Typically, the patient requires 4 to 5 mg. Intravenous meperidine (Demerol), given in 12.5 mg increments, can be used to supplement the midazolam. An antiemetic such as ondansetron (Zofran) is also administered during surgery. The amount of sedation is titrated to the point that the patient is somnolent, yet appropriately responsive. At this point, 3 mL of blood is drawn and transferred to the scrub nurse.

FIGURE 22-1 Drape support bar is attached directly to operating table.

A local field block is performed with 1% lidocaine with 1:100,000 epinephrine. A four quadrant block is performed in the meatus, and an additional injection is administered to the vascular strip and posteroinferiorly in the canal. Blanching of the canal skin is important for good hemostasis. Also important for good hemostasis is a snugly fitting speculum. The pressure provided by the speculum helps tamponade the vessels supplying the ear canal from the meatus. If one encounters troublesome bleeding during the procedure, a different speculum size can be tried, which typically results in improved hemostasis.

Surgical Technique

A tympanomeatal flap is incised using disposable tympanoplasty blades (7200 and 7210 BD Beaver). These disposable blades result in a sharp incision and rapid healing of the ear canal. Two incisions are made tangential to the annulus, one beginning adjacent to the short process of the malleus and following the tympanosquamous suture line. The second is adjacent to the tympanic annulus starting at approximately the 6 o’clock position and extending posterosuperiorly in the canal. These two incisions (Fig. 22-2) are connected with a transverse incision approximately 5 mm posterior to the tympanic annulus. The flap length is approximately the width of two Sheehy weapons (3 mm round knife). An excessively long flap would result in more bleeding, and can be difficult to fold forward in a narrow ear canal because of the bulk of the flap.

FIGURE 22-2 Canal incisions are outlined for the tympanomeatal flap.

The flap is elevated with a Sheehy weapon to the edge of the bony tympanic annulus. During this elevation process, the tip of the weapon is kept in contact with the ear canal bone. A No. 3 Baron suction is used behind the weapon, avoiding suction on the skin flap. A Rosen needle is used to enter the middle ear in a posterosuperior location. The tip of the instrument is placed through the middle ear mucosa, and the mucosa is divided. It is imperative not to place the instrument too deeply into the middle ear during this maneuver, or incus dislocation can occur. When the middle ear space is identified, the dissection is carried inferiorly, and the tympanic annulus is directly visualized. The annulus is elevated with the Rosen needle out of its sulcus. A House annulus elevator is also useful at this point. The annulus elevator is a blunt instrument, and if used posterosuperiorly, it too can result in incus dislocation.

The flap is elevated inferiorly to allow visualization of the round window (Fig. 22-3). It is elevated superiorly until the neck of the malleus is visualized. The chorda tympani nerve is adherent to the posterosuperior bony tympanic annulus. It is separated from this bone, and separated from the undersurface of the malleus. Separating the chorda tympani allows mobilization of the nerve inferiorly for good visualization of the stapes, and prevents injury during curetting.

FIGURE 22-3 Tympanomeatal flap is elevated exposing the neck of the malleus and the round window.

Posterior external auditory canal bone is removed with a curette to visualize the oval window. Initial curetting occurs several millimeters posterior to the edge of the tympanic annulus (Fig. 22-4). Initial curetting on the edge can result in displacement of the curette into the middle ear with dislocation of the incus. The posterior curetting allows for the bone to be weakened by creating a trough in this area. When the bone is weakened, the edge of the bone can be cracked off with the curette and little force is needed. The bone should be removed posteriorly to allow visualization of the stapedial tendon and pyramidal process (Fig. 22-5). For a right-handed surgeon working on a right ear, the bone should be removed superiorly so that half of the diameter of the horizontal fallopian canal can be visualized. For a right-handed surgeon working on a left ear, more curetting is necessary to introduce instruments in the middle ear, and bone should be removed so that the entire diameter of the horizontal fallopian canal can be visualized. At the conclusion of the curetting, all of the resultant bone chips should be removed from the ear canal to prevent postoperative healing problems.

FIGURE 22-4 Initial curetting begins posterior to the edge of the scutum.

FIGURE 22-5 Completed curetting exposes stapedial tendon, pyramidal process, and horizontal fallopian canal.

The incudostapedial joint is separated with a joint knife (Fig. 22-6). The joint is typically 1 mm medial to the undersurface of the incus and can be identified by pushing the incus slightly forward and laterally. The joint is separated with a side-to-side motion by the knife. When the joint is separated, the malleus mobility is tested to rule out idiopathic malleus head fixation. The stapes is tested for motion, and the anterior oval window is inspected visually for evidence of otosclerosis. Otosclerosis can reliably be seen in this area and appears to be bright white bone with prominent vessels on it. The adjacent normal otic capsule bone looks slightly gray compared with the otosclerotic bone. If otosclerosis is not visualized, one must be quite confident that the stapes is not mobile before proceeding (see the section on pitfalls).

FIGURE 22-6 Incudostapedial joint is separated with joint knife.

FIGURE 22-7. Stapedial tendon divided with laser.

FIGURE 22-8

Buy Membership for Surgery Category to continue reading. Learn more here