Assessment of multiple factors is necessary when evaluating the success rate of myringoplasty

Dear Editors,

We would like to address the manuscript by Carr et al. entitled ‘Factors affecting myringoplasty success’. ¹ This is an interesting study and constitutes excellent work. The authors evaluated the success of myringoplasty from the following five perspectives: experience of the surgeon, dry ear or not, the condition of the contralateral middle ear, perforation size, and the simultaneous performance of cortical mastoidectomy. It was concluded that, in adults, a significant association was evident between the tympanic membrane perforation site and the closure rate. Anterior and subtotal perforations had significantly lower closure rates. None of the factors evaluated significantly influenced tympanic membrane closure in a paediatric group. However, we believe that the factors assessed were not comprehensive. Also, the use of different graft materials has confused the findings.

The authors write, in the Methods section:

‘Inclusion criteria comprised perforations of the pars tensa, all age groups, and cortical mastoidectomy and myringoplasty for non-cholesteatoma ears. Exclusion criteria comprised cholesteatoma surgery and concomitant ossiculoplasty. … Potential influencing factors were surgeon grade (consultant, associate specialist or registrar); pre-operative condition of the ipsilateral middle ear (inactive or active chronic otitis media, with persistent or intermittent discharge); pre-operative condition of the contralateral middle ear (normal, otitis media with effusion, inactive chronic otitis media or active chronic otitis media); perforation site (anterior, posterior, inferior or subtotal); perforation size (0–20 per cent, 21–40 per cent, 41–60 per cent or subtotal); and simultaneous cortical mastoidectomy. The indication for a cortical mastoidectomy was myringoplasty in the presence of an actively discharging ear or a revision paediatric case’.

The authors did not assess the Eustachian tube or record concomitant myringosclerosis. Furukawa et al. suggested that removal of myringosclerosis at the edge of a perforation was beneficial when simple underlay myringoplasty was planned, improving the operative success rate and post-operative hearing threshold, especially when the myringosclerosis extended over the entire tympanic membrane. ² Migirov and Volkov believed that appropriate freshening of the perforation edges, with removal of sclerotic plaques, improved the success rate when tympanoplasty was performed in patients with concomitant myringosclerosis. ³ Pinar et al. found that the absence of myringosclerosis and a low middle-ear risk index were significantly (and independently) prognostic of successful tympanoplasty. ⁴ The Eustachian tube plays a significant role in the success of myringoplasty. One effect of Eustachian tube dysfunction in paediatric populations is that the middle-ear cavity is under negative pressure, which can cause retraction of the tympanic membrane, triggering failure of myringoplasty. ⁵ Collins et al. reported that Eustachian tube dysfunction was associated with a poor success rate of tympanoplasty. ⁶ Onal et al. performed a multivariate analysis of otological, surgical and patient-related factors, and concluded that smoking status increased the myringoplasty failure rate. ⁷ In addition, follow-up time may affect the success rates recorded in retrospective studies. Two studies reported re-perforation rates of 5–10 per cent in the first year after type I tympanoplasty, and rates of 10–15.5 per cent over the next 3–10 years. ^{8 , 9} Thus, factors affecting the success rate of myringoplasty should be analysed more thoroughly in future studies.

The authors write (in the Methods section): ‘Several different graft materials were used: temporalis fascia, perichondrium, perichondrium and cartilage, fat, and periosteum’. Five different graft materials were, in fact, used in the study. The indications for, and success rates associated with, different graft materials during myringoplasty differ. Fat grafts are used to repair small chronic tympanic membrane perforations. Konstantinidis et al. showed that fat graft myringoplasty was most successful when used to repair perforations smaller than 30 per cent of the pars tensa; the success rates decreased significantly when the perforations were larger. ¹⁰ Kim et al. also found that patients with perforations of more than 30 per cent had poor closure rates after fat graft myringoplasty. ¹¹ In addition, several studies have shown that tympanoplasty using cartilage (with or without perichondrium) was associated with better anatomical success rates than tympanoplasty employing temporalis fascia. ^{8 , 12 – 14} Ozbek et al. found that tympanoplasty using palisade cartilage was associated with a significantly higher graft acceptance rate (100 per cent) than tympanoplasty using fascia (70.2 per cent; p = 0.008). ¹⁵ Most scholars suggest that temporalis fascia will degenerate and shrink over time, triggering eardrum atrophy and re-perforation. ^{12 – 14 , 16} However, cartilage perichondrium can receive nutrients by diffusion, maintain bradytrophic metabolism and resist deformation by pressure variations. ^{12 – 14 , 17} Thus, factors affecting myringoplasty outcomes should be evaluated using the same graft material in future studies.