THE EFFECT OF TYMPANOSTOMY TUBES ON TYMPANIC MEMBRANE RETRACTION IN CHILDREN WITH CLEFT PALATE
Introduction
The role of tympanostomy tubes (grommets) in tympanic membrane atelectasis remains controversial.1 While they are commonly used to relieve negative middle-ear pressure with the intention of alleviating tympanic membrane retraction (TM), concern has been expressed that after extrusion, they may contribute to atelec-tasis.2 Children with cleft palate commonly receive tympanostomy tubes because of their predisposition to otitis media with effusion. They are also at higher risk of tympanic membrane retraction: around 44% of their ears have retraction compared with around 10% of ears in the general pediatric population.3,4 Of more concern, the prevalence of cholesteatoma is around 200 times more common in children with cleft palate.5 Greater understanding of the relationship between tubes and development of cholesteatoma from progressive retraction may help to lessen the burden of disease for these children.
As tympanostomy tubes are typically placed in the antero-inferior quadrant of the pars tensa, and never placed over the incus in the postero-superior quadrant, we hypothesised that retraction of the anterior or inferior segments of the pars tensa could be a direct consequence of TM atrophy from tube insertion, whereas retraction of the postero-superior retraction would not be. The objectives of this study are to determine: 1) whether anterior or inferior pars tensa retraction is more common after tube insertion; 2) whether postero-superior retraction is less common after tube insertion; 3) whether the severity of retraction correlates with the number of tubes inserted.
Method
Research ethics board approval was given for review of a cross section of our population of children with cleft palate attending a regional tertiary referral center for regular multi-disciplinary review over the course of one year. Prospectively acquired data included age, history of the number of tympanostomy tubes per ear, and digitally captured endoscopic TM images acquired after cerumen clearance. Cases with in-situ tubes, perforation, cholesteatoma or previous tympanoplasty were excluded. Cases were also excluded if the otoscopic image was of inadequate quality to allow assessment of the whole TM.
The TM images were analyzed for the presence and location of retraction of the pars tensa, noting whether retractions were present in the anterior and inferior segments or the postero-superior quadrant or both areas. Severity of retraction was based on a system described in Table 1 which was derived from the staging systems described by Sade and the Erasmus group.6,7
Analysis was with parametric and non-parametric statistical tests using SPSS software (Systat Software, Inc.).
This sample of children was previously described in an assessment of the reliability of endoscopic assessment of TM retraction.3
Table 1. Staging system used to describe severity of retraction
Stage |
Anterior or inferior retraction |
Postero-superior retraction |
1 | Retraction not in contact with promontory |
TM retraction not in contact with promontory, incus or stapes |
2 | Retraction touching or adherent to promontory | Retraction touching or adherent to incus or promontory |
3 | Erosion of bone (annulus or promontory) | Erosion of bone (incus, stapes, promontory or annulus) |
4 | Limits of retraction not visible | Limits of retraction not visible |
Results
Two hundred twenty-seven useable TM images were obtained from 143 children with cleft palate. The average age of these children was 13 years with a fairly even distribution of ages across the range of 4–18 years (Figure 1). The severity of tympanic membrane retraction across three different age groups is shown in Figure 2. There was no significant difference in severity of retraction in these different age groups (Spearman rank order correlation). A trend can be seen in Figure 2 suggesting relatively more stage-2 and less type-1 retractions in the youngest age group. Post-hoc comparison to analyze this observation revealed no significant difference (comparison of age with stage 1 versus age with worse retraction; comparison of age with stage 1 versus age with stage 2 retraction; p > 0.05, Mann-Whitney Rank Sum Test).
Fig. 1. Histogram showing distribution of study participants by age in years, representing a cross section of the whole population of children aged 5–17 years with cleft palate.
Fig. 2. Histogram showing number of ears at each stage of retraction by age. Stage of retraction is as defined in Table 1.
As shown in Figure 3, 198 (87%) ears had one or more tympanostomy tubes and 99 (44%) had two or more tubes. Fifty-one of 227 (22%) ears demonstrated an anterior or inferior retraction, 32 (14%) a postero-superior retraction, and 12 (5%) had both. To simplify interpretation, the small number of cases with retraction in both areas was excluded from the following analysis. Anterior or inferior retraction occurred in a greater proportion of ears that had received tubes compared with non-tubed ears (i.e., 47 (24%) versus 4 (14%)). Postero-superior retraction was relatively less common in tubed compared with non-tubed ears (i.e., 26 (13%) versus 6 (21%)). These differences were not significant (Fisher exact test). The proportion of cases with retraction at each site plotted by the number of tubes inserted is shown in Figure 4. No correlation was found between severity of retraction, at either site, and number of tubes (Spearman rank order correlation).
Fig. 3. Histogram showing distribution of number ears by number of tympanostomy tubes inserted.
Fig. 4. Proportion of ears with tympanic membrane retraction plotted by number of tubes inserted. Anterior or inferior retraction above; postero-superior retraction below.
The role of tympanostomy tubes in TM retraction remains controversial. While tubes have the potential to aggravate antero-inferior pars tensa retraction by causing TM atrophy, or to alleviate postero-superior retraction by relieving negative middle-ear pressure, this sample was too small to confirm either effect. Power analysis calculation indicates that a sample size of around 500 ears would be required to confirm the trends observed. The validity of the findings in this study have not been confirmed by repeated assessments of the TM images by the same or other observers: but as no significant differences were found with a single assessment, there was not felt to be adequate justification to repeat the observations.
The natural history of tympanic membrane retraction is poorly understood, with some TMs remaining stable for many years, some resolving spontaneously and some, seemingly a small minority, progressing into cholesteatoma. Even though risk factors for cholesteatoma development have been identified, such as that cleft lip and palate gives a higher risk than isolated cleft palate,5 it is not possible to predict the course or speed of this natural history in any given patient. This makes it difficult to determine the need for treatment in any given patient. It is also not possible to determine whether reported results of treatment, that may be administered to prevent ossicular erosion or cholesteatoma formation, are better than the outcome of no treatment.
In this context, more information about the relationship between tympanostomy tubes and TM retraction would be helpful, particularly for children at risk such as those with cleft palate. Separating how much their tendency to atelectasis and cholesteatoma is prevented or aggravated by the use of tubes from how much is due to their tendency to middle-ear disease (the same issue that leads to tube insertion) will be hard to determine. Well-defined indications for tube insertion, an ethically acceptable alternative to tympanostomy tube insertion (perhaps sub-annular tube placement or hearing aid) and follow up over many years would be prerequisites for prospective study of this relationship with a randomized controlled trial.
References
1.Nankivell PC, Pothier DD. Surgery for tympanic membrane retraction pockets. Cochrane Database Syst Rev (7):CD007943, 2010
2.Schilder AG. Assessment of complications of the condition and of the treatment of otitis media with effusion. Int J Pediatr Oto-rhinolaryngol 49(Suppl 1):S247–251, 1999
3.James AL, Papsin BC, Trimble K, Ramsden J, Sanjeevan N, Bailie N, Chadha NK. Tympanic membrane retraction: An endoscopic evaluation of staging systems. Laryngoscope 122:1115–1120, 2012
4.Maw AR, Hall AJ, Pothier DD, Gregory SP, Steer CD. The prevalence of tympanic membrane and related middle ear pathology in children: a large longitudinal cohort study followed from birth to age ten. Otol Neurotol 32:1256–1261, 2011
5.Harris L, Cushing SL, Hubbard B, Fisher D, Papsin BC, James AL. Impact of Cleft Palate Type on the Incidence of Acquired Cholesteatoma. Int J Pediatr Otorhinolaryngol. 2013 Feb 9. [Epub ahead of print]
6.Sade J, Avraham S, Brown M. Atelectasis, retraction pockets and cholesteatoma. Acta Otolaryngol 92:501–512, 1981
7.Borgstein J, Gerritsma TV, Wieringa MH, Bruce IA. The Erasmus atelectasis classification: proposal of a new classification for atelectasis of the middle ear in children. Laryngoscope 117:1255–1259, 2007
Address for correspondence: Adrian L. James, adr.james@utoronto.ca
Cholesteatoma and Ear Surgery – An Update, pp. 309–312
Edited by Haruo Takahashi
2013 © Kugler Publications, Amsterdam, The Netherlands