Introduction
Tympanic membrane perforation is a sequela of otitis media, and results mainly from middle-ear infection, trauma or iatrogenic causes.Reference Zhang, Huang, Zheng, Sun, Chen and Si 1 Traumatic tympanic membrane perforations tend to heal spontaneously, while tympanic membrane perforations associated with chronic suppurative otitis media usually fail to heal and may require tympanoplasty.
In 1960, Hermann introduced the use of a temporalis fascia graft in tympanoplasty.Reference Hermann 2 Since then, it has become the most widely used graft for tympanoplasty, as it is strong, durable, and easy to procure and handle.Reference Rizer 3 , Reference Wehrs 4 It has the added advantages of a low metabolic rate and high collagen content.Reference Abul-Hassan, von Drasek and Acland 5 , Reference Dabholkar, Vora and Sikdar 6 However, the type of temporalis fascia graft to use (i.e. dry or wet) remains controversial.
Some otologists prefer to harvest a temporalis fascia graft after elevating the tympanomeatal flap, just before graft placement in the middle ear. Such authors have suggested that better rates of closure are achieved using fresh, undried (wet) fascia because it is more ‘viable’.Reference Fisch, May and Linder 7 Advocates of fresh fascia argue that the survival of cellular elements, notably fibroblasts, is important in improving the survival of the grafted area, postulating that they play an active role in laying down collagen for the reparative process. The relative thickness and lack of form of fresh fascia, however, make it harder to position grafts precisely compared with parchment-like dried fascia.
Consequently, others favour harvesting the graft before the middle-ear procedure, and drying it with a hair dryer or via dehydration in anhydrous alcohol (dried fascia). Advocates of dried fascia argue that the fascia serves merely as a framework for the migration of epithelium over the perforation.Reference Pattersen, Lockwood and Sheehy 8
This mini-review investigates the impact of the nature of temporalis fascia grafts on the outcome of type I underlay tympanoplasty.
Materials and methods
A literature search was performed, using PubMed up to August 2016, to identify all studies of dry and wet temporalis fascia grafts in type I underlay tympanoplasty. The initial search using the key words ‘temporalis fascia’ and ‘tympanoplasty’ identified 130 articles; these were screened by reviewing the titles or abstracts based on the inclusion and exclusion criteria.
The inclusion criteria were: ‘dry’ and ‘fresh’ or ‘wet’ temporalis fascia; type I underlay tympanoplasty or myringoplasty; an intact ossicular chain and no mastoid surgery; and reports of the tympanoplasty success rate. Studies were excluded if: the participants were patients with a traumatic tympanic membrane perforation; they were reviews or comments; there was chronic suppurative otitis media with cholesteatoma and granulation tissue in the ear; or they were animal experiments. Ultimately, this review included seven articles.
Overview
Various factors influence the success rate of myringoplasty, including age, the portion of the tympanic membrane that has been perforated, the perforation size, post-operative otorrhoea, revision surgery and poor visualisation of the perforation margin.Reference Lee, Auo and Kang 9 – Reference Uyar, Keleş, Koç, Oztürk and Arbağ 18
In 1990, after analysing 64 consecutive paediatric tympanoplasties, Koch et al. concluded that age affected the surgical outcome.Reference Koch, Friedman, McGill and Healy 15 Vrabec et al. performed a meta-analysis of 30 studies spanning 3 decades that included age-specific data, and concluded that age was the only factor affecting the frequency of successful healing after surgery.Reference Vrabec, Deskin and Grady 16 Manning et al. studied tubal function in 63 patients for whom tympanoplasty was planned, and concluded that good contralateral Eustachian tube function predicted a good surgical outcome.Reference Manning, Cantekin, Kenna and Bluestone 17 Uyar et al. found that perforation or retraction of the contralateral tympanic membrane negatively affected graft integrity and hearing after tympanoplasty.Reference Uyar, Keleş, Koç, Oztürk and Arbağ 18 Similarly, Denoyelle et al.Reference Denoyelle, Roger, Chauvin and Garabedian 14 and Collins et al.Reference Collins, Telischi, Balkany and Buchman 19 reported that negative pressure in, and effusion or atelectasis of, the contralateral ear were associated with a poorly aerated middle-ear space after tympanoplasty. In addition, some authors believe that co-existing myringosclerosis may affect tympanoplasty outcomes, as excision of the myringosclerosis can improve success rates.Reference Migirov and Volkov 20
Temporalis fascia graft preparation
The preparation of a temporalis fascia graft is not complicated. The large area (260 mm2) of fascia on each side assures its availability, even in revision tympanoplasty. For a dry graft, in most studies, the temporalis fascia was removed immediately after the post-auricular incision, and then placed on and spread between glass plates and air-dried until it became rigid at room temperature.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 , Reference Loock and Naude 22 In one study, the graft was dried with a hair dryer for 3–5 minutes just before insertion in the middle ear.Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23 For a wet graft, the graft procedure was similar in many studies. The fascia was taken immediately before placing the fascial graft or just before placement in the middle ear.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 – Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23 The preparation of a wet graft is relatively simple, timesaving and convenient compared with the preparation of a dry graft.
Fibroblast counts in temporalis fascia grafts
Some scholars have predicted the effects of dry or wet temporalis fascia grafts on the outcome of tympanoplasty based on the fibroblast count in the graft.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 – Reference Smyth, Kerr and Nevin 25 Before placing a graft, samples of both wet and dry grafts were taken for histological examination using high-power field microscopy to determine the fibroblast count. Alkan et al.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 and Singh et al.Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23 found that the fibroblast count in the wet graft group was significantly higher than in the dry graft group (p < 0.01). Nevertheless, no morphological degenerative changes were observed in the fibroblast nuclei, irrespective of the nature of the graft. However, Patterson et al.Reference Patterson, Lockwood and Sheehy 24 and Smyth et al.Reference Smyth, Kerr and Nevin 25 failed to grow fibroblasts from temporalis fascia in their studies. Walby et al. managed to grow fibroblasts from both dry and wet fascia grafts,Reference Walby, Kerr, Nevin and Woods 26 giving credence to the theory that there are no pathological differences between the two temporalis fascia graft types.
Tympanoplasty outcome
Some otologists have considered whether the nature of a temporalis fascia graft affects the outcome of type I tympanoplasty. However, only three comparable studies have reported the relative success rates of fresh versus dried temporalis fascia.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 – Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23 Most authors suggested that good perforation closure is obtained when using dry and dehydrated grafts.Reference Aslan, Uslu, Köybașioğlu, Oz, Ileri and Ozbilen 27 , Reference Bhardwaj, Verma and Puri 28 However, Singh et al. found that the dry and wet graft groups had overall surgical success rates of 82 and 90 per cent, respectively.Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23 Alkan et al. reported a success rate of 91.4 per cent in the wet graft group and 88.6 per cent in the dry graft group.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 There were no intergroup differences in terms of recurrent disease, residual disease or post-operative hearing results (p > 0.05). They concluded that a dry or wet temporalis fascia graft does not influence the outcome of type I tympanoplasty, but using wet grafts can shorten the operating time.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 In a randomised controlled trial of fresh, dried and dried-then-rehydrated temporalis fascia in myringoplasty, successful closure of the perforation was achieved in 89 per cent of the dried fascia group, 84 per cent of the fresh fascia group, and 85 per cent of the dried-then-rehydrated group; however, the differences among the three groups were not significant (p = 0.728).Reference Loock and Naude 22 Theoretically, the use of a wet or dry temporalis fascia graft does not affect the success rate of type I tympanoplasty.
Eardrum healing is dependent on epithelial proliferation and centripetal migration. Fascia serves merely as a framework for the migration of epithelium over the perforation, and it does not completely replace, or become incorporated into, the eardrum during tympanoplasty. The application of biological materials (Gelfoam, collagen sponge or bacterial cellulose) alone has also been used to repair chronic tympanic membrane perforations in chronic suppurative otitis media cases, and has improved the success rate of myringoplasty.
An experimental study using Gelfoam, fat and a connective tissue graft showed that epithelial cells had been ‘pushed up’ against the graft, and had been split into two layers, of which one moved along the outer side of the graft and one along the medial side.Reference Reijnen and Kuijpers 29 The grafts showed signs of degeneration and were gradually replaced by newly formed connective tissue (in the middle layer of the eardrum) after tympanoplasty. In a cat study, autologous fascia seldom retained its structure and integrity after myringoplasty, suggesting that graft fibroblast survival was unlikely.Reference Salén and Wersäll 30 In 1982, Shenoi reported that the dehydration of temporalis fascia led to degeneration of the collagen matrix in grafts.Reference Shenoi 31 However, Shenoi reasoned that the subtle heat used for graft drying during myringoplasty has only a minimal effect on the denaturation of collagen fibres.Reference Shenoi 31
A dry graft may become wet after insertion into the middle ear if bleeding develops at the perforation edges and in the middle-ear mucus. During spontaneous healing of traumatic tympanic membrane perforations with eardrum bridges, Lou found that a few bridges gradually became necrotic and merged into the newly healed eardrums.Reference Lou 32 In addition, when a dry graft is placed in the wet physiological environment of the middle ear, it will shrink and lose contact with the remnant margins of the tympanic membrane under which it is tucked, especially anteriorly, and cause graft failure.Reference England, Strachan and Buckley 33 , Reference Chow and Wei 34 Indorewala also observed shrinkage and thickening of temporalis fascia grafts in an experimental study conducted on dogs in 2002.Reference Indorewala 35
Based on the aforementioned studies,Reference Reijnen and Kuijpers 29 – Reference Indorewala 35 it may be reasoned that dry or wet grafts have minimal impact on graft uptake.
Many scholars have attempted to evaluate the success rate of tympanoplasty using the fibroblast count in grafts. They inferred that fibroblasts lay down collagen during the wound repair process, with the formation of a granulation tissue matrix to allow the spread of epithelialisation, which promotes successful graft uptake. Fresh or wet fascia had surviving cellular elements, notably fibroblasts.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 , Reference Loock and Naude 22 , Reference Kumar, Abbas, Fausto, Aster, Kumar, Abbas and Fausto 36 The degeneration of fibroblast nuclei occurs with the dehydration of a temporal fascia graft or with greater spreading of the nuclei in a dry graft. Therefore, better closure rates are obtained by using a wet graft. However, two clinical studies showed that although the fibroblast count in the wet graft group was significantly higher compared with that in the dry graft group (p < 0.01), the success rates of dry and wet grafts were not significantly different in terms of their relative fibroblast counts.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 , Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23
It is important to evaluate whether the nature of the graft affects the outcome of tympanoplasty. Ideally, healed tympanic membranes should be evaluated histologically after tympanoplasty, thereby allowing the natural course of the graft to be evaluated. However, this is obviously impossible ethically. Therefore, additional experimental studies are needed. Clinically, we may monitor the morphological changes in grafts and perforation edges on a daily basis after tympanoplasty (without packing the external auditory canal), either otoendoscopically or microscopically.
Indirect effects of wet grafts
Although the nature of the graft did not directly affect the outcomes of tympanoplasty, we consider that the use of wet grafts ensures that the perforation edges are kept moist, prevents tissue dehydration and necrosis, facilitates hyperblastosis of granulation tissue at the perforation edges, and accelerates eardrum healing.
When studying spontaneous healing of traumatic tympanic membrane perforations, Lou et al. found that wet (compared with dry) conditions improved the closure rate and reduced the closure time.Reference Lou, Wang and Su 37 Singh et al.Reference Singh, Kumar, Aggarwal, Garg, Arora and Kumar 23 and Alkan et al.Reference Alkan, Baylanĉiĉek, Sözen, Baŝak and Dadaŝ 21 found that although the difference between the success rates of the grafting procedures using dry or wet temporalis fascia was not significant, the success rate in the wet graft group was slightly higher than that in the dry graft group (92 per cent vs 82 per cent (Singh et al.) and 91.4 per cent vs 88.6 per cent (Alkan et al.), respectively). Some clinical studies of type I tympanoplasty outcome also found that a wet middle-ear mucous membrane improved the success rate compared with a dry ear.Reference Koch, Friedman, McGill and Healy 15 , Reference Caylan, Titiz, Falcioni, De Donato, Russo and Taibah 38 Nagle et al. suggested that the presence of discharge in the ear at the time of the operation does not interfere with the results of tympanoplasty.Reference Nagle, Jagade, Gandhi and Pawar 39 Therefore, wet grafts may indirectly affect the outcomes of tympanoplasty. In addition, placement of wet grafts saves time, and is simple and convenient.
Acknowledgements
This study was supported by: the Science and Technology Agency of Zhejiang Province, the Health and Medicine Agency of Zhejiang Province, and the Science and Technology Agency of Yiwu, China (grant numbers 2013C33176, 2015KYB420 and 2015-3-06, respectively).
