Trichloroacetic acid Alloderm™ Myringoplasty as a novel option for tympanic membrane reconstruction in children

Tympanic membrane (TM) perforations are common in pediatric patients and can limit participation in water activities and result in conductive hearing loss, otorrhea, and chronic suppurative otitis media. TM perforation can also serve as a conduit for keratinized squamous epithelium entry into the middle ear, becoming trapped and progressing to cholesteatoma. Furthermore, there is evidence that the partial pressure of middle ear oxygen with an intact tympanic membrane is below that in atmospheric air. This pressure differential can result in the production of oxygen free radicals, injuring cochlear outer hair cells and resulting in premature sensorineural hearing loss. Lastly, the physiologic state of the middle ear is believed to be sterile which is impossible in the face of a chronic perforation. Speculation as to the pathophysiologic consequences of continuity of outer and middle ear space has been postulated. Management of TM perforations ranges from observation (many acute traumatic perforations heal spontaneously) to reconstructive surgery, most typically involving tympanoplasty techniques.

Precise cautery was first described as a treatment for granulation tissue in the ear canal or on the TM itself in the 1800s by otolaryngologist William Wilde, father of Oscar Wilde. As one might expect, cautery was not, at first, accepted as a treatment for TM perforations. In 1860, Bonnafont trialed cautery as a method of preserving a perforated TM only to find a perfectly healed eardrum three months later. Since that time, many types of cautery have been studied and published to achieve closure of TM perforations including silver nitrate, zinc sulfate, trichloroacetic acid, nitric acid, and chromic acid [1]. Cautery works by breaking up the outer layer of squamous epithelium that has grown inward across all five layers of the tympanic membrane. By destroying this layer, fibroblastic proliferation can proceed. Mild irritation also induces fibroblastic proliferation via hyperemia. The final piece of the puzzle is keeping the fresh edges moist to prevent desiccation and inactivation of fibroblasts [2].

Surgery as a one-stop-shop procedure to repair the TM was first proposed by Berthold who, in 1878, described the use of plaster to de-epithelialize the tympanic membrane, with subsequent application of full thickness skin grafting to assist with perforation closure. Since that time many techniques for TM reconstruction and types of grafts have been utilized to surgically reconstruct perforated tympanic membranes [3].

The first branch in the decision tree is whether the perforation can be healed with a simple myringoplasty. Myringoplasty is patching of the tympanic membrane perforation without elevating the middle ear and is typically considered in any patients with small and nonmarginal perforations. It works by freshening the rim of the scar around the tympanic membrane and forgoes any canal or external incisions [4], [5]. Additionally, the myringoplasty technique has been expanded to include less favorable perforations including anterior perforations using endoscopic techniques [6], [7], [8].

For perforations that do not fit the above criteria to undergo simple myringoplasty, a tympanoplasty can be performed. Tympanoplasty by definition involves the raising of a tympanomeatal flap. This step provides access to the middle ear and allows for repair of larger and marginal perforations. It also allows for manipulation of the ossicles and provides the opportunity to address middle ear pathology. Notably, a postauricular incision is occasionally required for access to anterior perforations adding to the morbidity and postoperative recovery time. There are several options for graft placement. These techniques are generally broken down into inlay, underlay (medial), and overlay (lateral) procedures. Inlay or medial grafts are chosen for patients with more mild middle ear disease or for small nonmarginal perforations whereas lateral grafts are used in more severe cases [9].

Another choice when surgically repairing a perforated eardrum is the type of graft. Grafts used for tympanoplasty generally break down into autologous and non-autologous grafts. Numerous autologous tissues have been used as grafts including temporalis fascia, fascia lata, periosteum, perichondrium, cartilage, veins, fatty tissue, and skin. The most commonly used graft is the temporalis fascia graft due to its ease of use/harvest and well published outcomes. Cartilage is a close second, usually reserved for revisions or cases in which the middle ear disease is more severe and/or a stiffer graft is required (e.g. dimeric tympanic membrane retraction pocket) [10], [11], [12], [13]. Non-autologous grafts range from simple (such as cigarette paper, Steri-Strip, and Gelfoam) to more complex/processed synthetic materials (such as human dermis – AlloDerm™, human pericardium – Tutoplast®, and porcine submucosa – Biodesign®). Several studies have compared the complication rates between non-autologous grafts and autologous grafts and have not shown any differences or concerns regarding the safety of such grafts [14], [15], [16], [17]. In addition, one retrospective review comparing autologous and non-autologous grafts as above showed similar rates of success between the two groups suggesting that non-autologous materials may be a viable alternative to traditional autologous grafts [13].

Our study aimed to describe a novel technique which combines and modifies concepts including expanded myringoplasty techniques, synthetic grafting, and trichloroacetic acid cautery to spare autologous graft harvest, forgo canal incisions, and shorten surgery time while achieving similar outcomes when compared to other standard tympanoplasty methods. To the best of our knowledge, this has not been documented or attempted in the pediatric population.

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