Surgical Management

The main goal of surgery is to restore and maintain patency of the external auditory canal for normal sound transmission and maintenance of the canal's self-cleaning functions. If the ear is actively discharging, it is best to decrease the inflammatory process with cleansing and topical steroid-antibiotic therapy. Surgery can proceed when the ear is no longer draining.

Visualization Tympanic Membrane

FIGURE 23-1 Coronal computed tomography (CT) of soft tissue stenosis with cholesteatoma (arrow) medial to stenosis and lateral to tympanic membrane. Stenosis due to psoriasis.

The authors prefer the postauricular approach for removal of both bony and soft tissue external auditory canal stenosis. The postauricular approach provides much better visualization and allows easier access for drilling compared to the endaural and transcanal approaches. In addition, the postauricular incision is more cosmetically appealing than the endaural incision. For exostosis removal, the postauricular incision allows for maximum preservation of canal skin and facilitates removal of the anterior exostosis, which is usually close to the tympanic membrane.

Bony Stenosis

The procedure is begun by first injecting the ear canal skin with 1:100,000 epinephrine for hemosta-sis. A curvilinear postauricular incision is made approximately 1 cm behind the postauricular fold. The incision is carried directly down to bone inferiorly and down to the level of the temporalis fascia superiorly. A self-retaining retractor is placed, and the area of the spine of Henle is located by identifying the inferior border of the temporalis muscle. Dissection is carried anteriorly along the

Postauricular Fold
FIGURE 23-2 Retraction of posterior canal skin with tympanoplasty retractor.

mastoid bone in the region of the spine of Henle to identify the bony external meatus. Once the meatus is identified, the skin overlying the lateral surface of the posterior exostosis is elevated. The skin is elevated carefully with a Guilford or duckbill elevator as far medially as possible. Every attempt should be made to preserve as much canal skin as possible. Once elevated, the skin is retracted anteriorly with the blade of a House or Perkins bladed tympanoplasty retractor (Fig. 23-2). Placement of the tympanoplasty retractor allows further visualization of the medial skin dissection. Skin elevation is then completed as far medially as possible.

The posterior bony exostosis(es) is (are) removed using a medium-size diamond bur with suction-irrigation. The bony dissection is carried medially while keeping a protective shell of bone between the bur and the ear canal skin (Fig. 23-3). Bone removal is continued medially and posteriorly until the normal dimensions and contour of the ear canal are achieved.

The tympanic membrane and posterior annulus cannot be seen with this approach. Therefore, as drilling approaches the annulus, the surgeon may have to remove the tympanoplasty retractor and

FIGURE 23-3 Drilling of posterior canal wall for exostosis. Bony shell left to protect skin.

move the posterior canal skin posteriorly to judge the amount of remaining posterior bony stenosis. Care must be taken to avoid damage to the chorda tympani nerve, the posterior tympanic membrane, and the facial nerve. The facial nerve may lie lateral to the tympanic annulus in the lower part of its vertical segment.6 Once the posterior bony removal is completed, the protective bony shell is fractured and removed. To facilitate removal, the ear canal skin must be thoroughly elevated off this shell prior to its removal.

If anterior exostosis(es) is (are) present, a laterally based posterior flap is created in the posterior canal skin. The laterally based flap is involuted into the meatus and held out of the way with the blade of the tympanoplasty retractor (Fig. 23-4A). The anterior exostosis is now exposed. To remove the anterior exostosis(es), an anterior, laterally based canal skin flap is created. The flap is formed by making a skin incision parallel to the tympanic membrane over the midportion of the anterior exostosis (Fig. 23-4B). Inferior and superior incisions made from the edge of this first incision are then extended laterally. The anterior, laterally based flap is elevated laterally and held out of the way along with the posterior flap using a tympanoplasty retractor. The remaining skin over the anterior exostosis is elevated as far medially as possible. The exostosis is drilled in a fashion similar to that used to remove the posterior exo-stosis.

Anterior exostoses are often very close to the tympanic membrane. To protect the medial, anterior canal skin, a piece of tympanic membrane-size thin Silastic or the aluminum foil of a suture package is placed on the inside surface of the anterior canal skin to hold it down against the tympanic membrane during drilling. This material protects the anterior canal skin and tympanic membrane from the drill. At the completion of bony removal, the protective material is removed and all skin flaps are folded back into position over the new shape of the ear canal. The postauricular incision is closed in layers using 3-0 and 4-0 Vicryl suture, respectively, in a subcutaneous and subcuticular fashion.

The ear canal is then lined with a piece of thin (approximately 0.005 inch) Silastic. The Silastic helps to prevent blunting and stenosis of the ear canal during the postoperative period. The width of the

Posterior flap involuted into ex lerna I me alus

Posterior flap involuted into ex lerna I me alus

Posterior Semicircular Canal Occlusion

Posterior flap involuted

Anterior skin Haps

FIGURE 23-4 (A) Laterally based posterior flap involuted into external meatus. (B) Laterally based anterior flap created to expose anterior exostosis.

Posterior exostosis removed o

Posterior flap involuted

Anterior skin Haps

FIGURE 23-4 (A) Laterally based posterior flap involuted into external meatus. (B) Laterally based anterior flap created to expose anterior exostosis.

CHAPTER 23 CANALOPLASTY FOR CANAL STENOSIS

Xeroform packing inside of silastic

Xeroform packing inside of silastic

Blunting Anterior Canal Wall
FIGURE 23-5 (A) Thin Silastic sheeting rounded in one end to accommodate additional length of anterior ear canal. (B) Silastic sheeting unrolled against canal skin with Xeroform packing used as a tamponade.

Silastic should be equal to the length of the ear canal from the posterior tympanic membrane to the external meatus. The length should be approximately 5 to 6 cm. One end of the Silastic should be rounded slightly wider than the other end to accommodate the additional length of the ear canal from the anterior drum to external meatus (Fig. 23-5A). To place the Silastic, it is rolled tightly along its width and positioned in the ear canal with the longer edge facing the anterior sulcus. It is allowed to unroll in the ear canal against the ear canal skin. This maneuver is facilitated by grasping the outside edge of the Silastic with bayonet forceps and the inside edge with cup forceps. The bayonet forceps stabilize the Silastic while the cup forceps are used to unroll it. Xeroform gauze is packed tightly inside the Silastic to keep the Silastic against the walls of the ear canal (Fig. 23-5B). A cotton ball impregnated with bacitracin ointment is placed in the meatus and a standard mastoid dressing is applied. Bacitracin ointment is applied to the cotton ball to prevent adherence to the Xeroform during removal of the cotton ball.

Soft Tissue Stenosis

In addition to the ear, the volar forearm is prepped and draped in preparation for a possible skin graft. The procedure is then begun by injecting the ear canal skin with 1:100,000 epinephrine for hemosta-sis. If the soft tissue stenosis fills the entire external canal, a postauricular incision is made and the temporalis muscle identified in the same manner as that described for bony stenosis removal. If the soft tissue stenosis fills only a portion of the medial canal, a circumferential skin incision is made just lateral to the stenosis. This incision is connected to the external meatus through two canal incisions over the regions of the tympanomastoid and tympanos-quamous suture lines. A postauricular incision is then made and the temporalis muscle found. The external meatus is identified and, if canal incisions have been made, the posterior, laterally based flap is involuted out of the way and held in place with a tympanoplasty retractor. The lateral edge of the stenosis is now in view.

The fibrosis is dissected circumferentially off bone using a Guilford or duckbill elevator. Dissection is

Fi h nisi s elevated

Fi h nisi s elevated

Skin Flap Over Tympanic Membrane

Dissection over fibrous drum (drum intact)

Bone

Canal skin

FIGURE 23-6 (A,B) Dissection along posterior plane of soft tissue stenosis.

Dissection over fibrous drum (drum intact)

Bone

Canal skin

FIGURE 23-6 (A,B) Dissection along posterior plane of soft tissue stenosis.

carried medially to the tympanic annulus (Fig. 23-6). When the stenosis is excessively thick, segmental removal of portions of the fibrosis may allow better visualization of the tympanic membrane. Care is taken when approaching the tympanic membrane to prevent a perforation. An avascular plane between the soft tissue stenosis and the fibrous drum should be developed. The plane can usually be established along the inferior annulus or over the short process of the malleus. Inadvertent elevation of the annulus may occur if dissection is begun posteriorly rather than inferiorly. Elevation of the annulus at this time will make dissection difficult. Every attempt should be made to preserve the fibrous layer of the tympanic membrane. After the fibrous plug is elevated from the tympanic membrane, the entire soft tissue stenosis is removed and sent for pathologic examination. To prevent recurrence, it is imperative that the entire cleaned fibrous annulus be visible, especially in the anterior sulcus.

Enlargement of the bony canal is necessary in all cases for three reasons. First, the bony anterior canal bulge often prevents complete visualization of the anterior sulcus. Fibrous tissue could be missed if the anterior bulge is left in place. The most common source of re-stenosis is in the anterior canal sulcus. Second, enlargement helps to maintain ear canal patency despite the tendency for soft tissue to narrow the canal during the healing phase. Third, a large ear canal allows easier postoperative inspection and cleaning.

Bony canaloplasty is performed initially with a medium cutting bur and suction-irrigation. Grooves are drilled above and below the region of the glenoid fossa. The region between these two grooves is thinned using a diamond bur until an eggshell layer of bone is left over the glenoid fossa. Drilling must be performed carefully in the anterior canal because inadvertent entry into the glenoid fossa may result in herniation of fat into the ear canal. Herniation of fat may result in further stenosis. Additional drilling medial to the glenoid fossa is often necessary to completely expose the anterior fibrous annulus. A small diamond bur should be used in this area to minimize vibration to the ossicular chain. To prevent anterior canal blunting, the final angle between the tympanic membrane and anterior bony wall should be approximately 90 degrees. Any remaining fibrous tissue in the anterior sulcus should be removed at this time. The posterior canal wall is widened until mastoid air cells are visualized but not opened. A diamond bur should be used when working near the tympanic membrane. Once bony canaloplasty is completed, the surgeon should be able to view the entire annulus from one position of the microscope.

A posterior tympanotomy should be performed in cases with suspected middle ear disease. Up to 25% of cases of soft tissue stenosis may have middle ear pathology such as ossicular defects, cholesteatoma, or otosclerosis.10 Sometimes a tympanic membrane perforation occurs during dissection over the drum. If it does, a standard underlay graft tympa-noplasty should be performed.

Removal of the fibrous plug along with bony canaloplasty results in a wide ear canal. For this reason, a meatoplasty is often necessary. The mea-toplasty should widen the external meatus sufficiently to allow easy visualization of all margins of the newly created external canal. Meatoplasty is performed through the postauricular approach by first removing a semilunar piece of conchal cartilage near the margin of the external meatus. The index finger of the nondominant hand is placed in the external meatus while the soft tissue overlying the conchal cartilage is carefully removed using cutting Bovie cautery. The nondominant hand is used to prevent inadvertent penetration of the cutting tool through the conchal skin. Once the cartilage is identified, a semilunar piece of conchal cartilage is removed using a No. 64 Beaver blade, which has a rounded tip scalpel that cuts at the tip as well as on one side. After conchal cartilage is removed, two incisions approximately 1 to 1.5 cm in length are made; the first is through the incisura and the second is made through conchal skin and cartilage at approximately the 4 o'clock position in a right ear and the 7 o'clock position in a left ear. Each of the two incisions must extend through all layers of subcutaneous tissue. A nonabsorbable suture is then used for permanent retraction of the posterior external meatus. After the meatoplasty is completed, the postauricular incision is closed in layers using 30 and 4-0 Vicryl suture in a subcutaneous and subcuticular fashion, respectively.

Finally, a thin split-thickness skin graft is obtained and used to cover all areas of exposed canal bone. The skin graft helps to prevent granulation tissue and re-stenosis, and speeds healing. For small defects, skin may be obtained from the non-hair-bearing region of the postauricular area. A No. 10 blade scalpel is used to shave an appropriate size graft. While obtaining the graft, the blade should be visible through the skin at all times to ensure a thin graft. Xeroform gauze is placed over the donor site. For large defects, the authors prefer to obtain the skin graft from the volar aspect of the ipsilateral upper arm. The skin of this area is ideal because it is thin and pliable and often lacks hair follicles. To obtain the graft, a rectangular area of skin of adequate dimensions (a 6 x |2-cm graft is necessary to cover the entire canal and drum) is infiltrated with lidocaine with 1:100,000 epinephrine. The harvest site is then lightly coated with mineral oil, and the arm is grasped firmly on the lateral aspect to provide tension on the volar surface. With a razor blade secured lengthwise in a curved clamp, a gentle back-and-forth slicing motion is used to harvest the graft. The proper thickness is obtained when the leading edge of the razor blade is barely visible beneath the skin graft. If performed properly, the graft thickness is approximately 0.010 to 0.012 inch in thickness.16 The donor site is covered with Xeroform and wrapped with gauze. Both the postauricular and forearm donor sites heal with little or no cosmetic deformity.

The skin graft is then used to cover all areas of exposed bone in the external canal. The skin graft should also cover the tympanic membrane if the epithelial layer has been removed from the drum. When a graft is required to cover the drum, notches are cut on both sides of the graft. These notches correspond to the level of the anterior tympanomea-tal angle. The anterior portion of the graft may be trimmed to a width slightly less than the posterior portion. In this way, the graft may fold around the posterior canal (Fig. 23-7A). The skin graft is placed in the ear canal with the short portion over the anterior canal wall. The notched area is folded at the anterior angle, whereas the larger area covers the drum and posterior canal (Fig. 23-7B). The graft should be sutured to the external meatus with a chromic suture if there is exposed bone near the external meatus. Suturing of the graft at the external meatus is necessary to maintain proper contact of the graft in this area. Compressed Gelfoam soaked in antibiotic-steroid otic solution is tightly packed into the anterior sulcus and around the tympanic annu-lus.

Regardless of the size of the skin graft, the ear canal is lined with Silastic as described previously for treatment of bony stenosis. The Silastic must extend up to the anterior sulcus to prevent blunting in this area. Xeroform gauze is packed tightly inside the Silastic to keep the Silastic against the skin graft and walls of the ear canal. A cotton ball impregnated with bacitracin ointment is placed in the meatus and a standard mastoid dressing is applied.

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