Office Myringoplasty With Alloderm

Tympanic membrane (TM) perforations arise from chronic middle ear infections, trauma, or placement of ventilation tubes. Most acute TM perforations spontaneously heal. In fact, acute perforations begin healing after 12 hours when squamous cells at the edges of the perforation begin to proliferate. 649 When the healing process is complete, a neomembrane or replacement membrane is formed. 650 This neomembrane is thinner than the normal TM as a result of lack of a middle fibrous layer. A chronic perforation results from failure of epithelial growth across the perforation. When the TM fails to heal spontaneously, surgery is often necessary to close the perforation. Attempts have been made to repair perforations of the tympanic membrane dating as early as 1640 by Banszer 651 when he used a small tube of elk horn surrounded by pig's bladder. Since then, a host of materials have been used for the repair of TM perforations. Berthold, 652 who introduced the term “myringoplasty,” successfully repaired a TM perforation using a full thickness skin graft in 1878. Other materials used included split thickness skin grafts, vein grafts, sclera, perichondrium, temporalis fascia, cartilage inlay, and fat. 653, 654 If the perforation is small, central, and dry with no evidence of middle ear disease, more conservative measures, such as an office myringoplasty under local anesthesia, may be undertaken. We report the use of AlloDerm® (Life Cell Corp., The Woodlands, TX) for office myringoplasty with success. AlloDerm®, an acellular human dermal matrix, is a new biomaterial that serves as a connective tissue matrix, providing soft tissue support and coverage that becomes integrated into the implanted bed. 655, 656 AlloDerm® is processed from human donor skin obtained from an approved tissue bank. Donors are screened for HIV types 1 and 2, human T-lymphotrophic virus type I, hepatitis B and C, and syphilis. 655-657 In addition to the safety margin generated through donor screening and serological testing guidelines, the processing of AlloDerm® increases this safety margin in two ways. 657 All the cells within the dermal tissue are solubilized, leaving no potential reservoir for viral replication. Furthermore, this detergent decellularization step has been shown to actually inactivate high titers of HIV. Removal of cellular components of the skin, the target of the rejection process, reduces the chances of an immune response in the recipient. Using a special freeze-drying technique preserves the integrity of the matrix protein of the AlloDerm® graft. This reduces inflammatory tissue reaction. AlloDerm® has been successfully used as a soft tissue graft for cosmetic and reconstructive surgery. 655, 658 Seven patients were included in the study. All patients sustained traumatic central perforation of approximately 10% to 30% of the TM in one ear. These perforations failed to close spontaneously over 6 months. On examination of each of the patients, there was no evidence of middle ear pathology or abnormality of tympanic membrane except for a dry central perforation. Audiograms revealed a mild conductive component consistent with the TM perforation. The details of AlloDerm® myringoplasty were explained to the patients. They were also informed regarding the alternatives, including observation, hearing aid, fat myringoplasty, or a formal tympanoplasty. The procedure was performed in the office. The freeze-dried AlloDerm® graft comes in small, prepackaged pieces that are stored in a refrigerator. For the purpose of this study, special thin-sectioned pieces of AlloDerm® (thickness = 300 μm) were used. The graft was taken out of the package and rehydrated in sterile saline with two washes for at least 5 minutes each. The external auditory canal was injected with 1% lidocaine with 1:100,000 epinephrine in all quadrants. The perforation was rimmed with a Rosen needle. The outer epithelial layer around the perforation was removed using a round knife. 654 A small piece of AlloDerm®, approximately 1.5 times the size of the perforation, was trimmed and placed over the perforation using a cup forceps. Using a Rosen needle, the AlloDerm® graft was then pushed slightly medially so that the graft projected on both medial and lateral aspects of the perforation. A small piece of Gelfoam (Pharmacia and Upjohn Co., Kalamazoo, MI) soaked in antibiotic solution was placed in the canal and a small cotton ball was placed in the meatus. The patient was discharged subsequently with instructions to keep the ear dry and to avoid nose blowing for 6 weeks. No antibiotics or analgesics were prescribed. All patients were followed up for at least 1 year after AlloDerm® myringoplasty. All seven patients who underwent AlloDerm® myringoplasty tolerated the procedure without any difficulty. There were no surgical complications. At 2-week postoperative follow-up, there was evidence of neo-epithelialization, which continued for 2 to 4 months depending on the size of the perforation. Complete healing (Fig. 1) and improvement in hearing (Fig. 2., Fig. 3.) oc curred in all patients except one. This patient was noted to have mild discharge on weekly follow-up visits. This patient was not able to comply with dry ear precautions. Despite local measures and topical antibiotics, the graft failed to heal. He was scheduled for a tympanoplasty in the operating room. Atrophy or rejection of the graft was not noted in any patient during 1-year follow-up. AlloDerm® graft in the left ear 4 months after myringoplasty. Note that the graft is incorporated in the tympanic membrane. Preoperative audiogram of a representative patient showing a conductive HL. Postoperative (4 mo) audiogram of the same patient as in Figure 2 showing improved hearing with closure of the air–bone gap. Popular scaffolding materials, used in an office myringoplasty, include the paper patch and fat plug. The paper patch is placed over the lateral surface of the perforation to provide a temporary means for the migration of the epithelial cells. Much investigation has been performed examining the healing characteristics of fat myringoplasty both in the animal model and patients. 659-661 The success rate with fat myringoplasty ranges from 76% to 92%. 654, 661-663 In a guinea pig model, success rates were better with fat compared with paper patch and control. 660 This may in part be the result of fat functioning as both a lateral and a medial surface graft. 663 However, fat atrophy over time precludes its use for larger perforations. Therefore, fat myringoplasty is recommended only for small perforations (less than 2 mm). 663, 664 In this study, we were able to close perforations of up to 30% of the TM. An ideal graft material for myringoplasty would be one that is permanent and that promotes migration of epithelium from the advancing edge of the perforation both on the lateral and medial surfaces of the TM. Histological evaluation would be required to determine if AlloDerm® possesses these characteristics. Youssef 665 has recently described the use of AlloDerm® for tympanoplasty with a successful outcome. However, all his cases were done in the operating room under general anesthesia with middle ear exploration. All the patients in our study underwent office myringoplasty under local anesthesia. The procedure is fast and effective with minimum morbidity. The patients were not exposed to general anesthesia and there was no loss of working days. It also reduced the cost associated with conventional outpatient tympanoplasty procedures in this selected group of patients. AlloDerm®, an acellular human dermal matrix, is a new biomaterial that serves as a connective tissue matrix, providing soft tissue support and coverage that becomes integrated into the implanted bed. In this study, AlloDerm® myringoplasty was successfully used in 6 of 7 patients with traumatic tympanic membrane perforations that failed to heal spontaneously. The advantages conferred by using AlloDerm® include ease of tissue graft handling for complete encompassment of the margins of the perforation, ready-to-use storable packaging, ease of tissue preparation, and no donor site morbidity. Such features allow AlloDerm® myringoplasty to be a fast, safe, and effective procedure in the office setting.