Download Tympanic membrane retraction

The Laryngoscope
C 2012 The American Laryngological,
V
Rhinological and Otological Society, Inc.
Tympanic Membrane Retraction: An Endoscopic Evaluation of
Staging Systems
Adrian L. James, DM, FRCS(ORL-HNS);
Blake C. Papsin, MD, FRCSC; Keith Trimble, MPhil, FRCS(ORL-HNS);
James Ramsden, MA, FRCS(ORL-HNS); Nadarajah Sanjeevan, MD;
Neil Bailie, PhD, FRCS(ORL-HNS); Neil K. Chadha, MPHe, FRCS(ORL-HNS)
Objectives/Hypothesis: The objectives of this work were to assess inter- and intraobserver variability of different staging
systems for tympanic membrane (TM) retraction using otoendoscopy in children at risk of retraction from cleft palate, to compare
hearing level with stage of retraction, and to propose optimum characteristics for monitoring TM retraction with endoscopy.
Study Design: Cross-sectional study.
Methods: Endoscopic images of 245 TMs of children with cleft palate (mean age, 13.0 years) were assessed on two separate occasions by six observers using the Sade and Erasmus staging systems for pars tensa retraction and Tos system for
pars flaccida retraction. Intra- and interobserver agreements were calculated. Extent of TM retraction was compared with
hearing threshold. TMs with middle ear effusion, tympanostomy tubes, or perforation were excluded.
Results: A total of 108 ear drums (44%) were rated as having pars tensa and/or flaccida retraction. Intraobserver
agreement was fair to moderate (kappa ¼ 0.3–0.37, P < .001) for the different staging systems and interobserver agreement
slight to moderate (0.18–0.41 P < .001). Conductive hearing loss (four-tone average air-bone gap >25 dB HL) was present in
11 ears (15%). No correlation between hearing threshold and retraction stage was found. Isolated tensa retraction onto the
promontory increased hearing threshold more than retraction involving the incus (P ¼ .02; analysis of variance).
Conclusions: Endoscopic image capture may provide a clear objective record of TM retraction, but current staging systems have unsatisfactory reliability when applied to such images, and retraction stage correlates poorly with hearing threshold. Modification of retraction assessment to improve validity and clinical relevance is proposed.
Key Words: Tympanic membrane retraction, staging system, cleft palate, hearing loss.
Level of Evidence: 2c.
Laryngoscope, 122:1115–1120, 2012
INTRODUCTION
Retraction of the tympanic membrane (TM) into the
middle ear can cause significant conductive hearing loss,
particularly as a result of ossicular erosion.1 Accumulation
of desquamated keratin within the retraction pocket (i.e.,
From the Department of Otolaryngology–Head and Neck Surgery
(A.L.J., B.C.P., N.S.), University of Toronto, Toronto, Ontario, Canada;
Department of Ear, Nose, and Throat Surgery (K.T.), Royal Belfast
Hospital for Sick Children, Belfast, United Kingdom; Ear, Nose, and
Throat Department (J.R.), John Radcliffe Hospital, Oxford, United
Kingdom; Department of Ear, Nose, and Throat Surgery (N.B.), Royal
Victoria Hospital, Belfast, United Kingdom; and Division of
Otolaryngology–Head and Neck Surgery (N.K.C.), British Columbia
Children’s Hospital, Vancouver, British Columbia, Canada.
Editor’s Note: This Manuscript was accepted for publication
December 21, 2011.
Presented at the 114th Triological Society Meeting, Chicago,
Illinois, U.S.A., April 27– May 1, 2011.
This work was performed entirely at the Department of Otolaryngology–Head and Neck Surgery, Hospital for Sick Children, Toronto,
Ontario, Canada.
The authors have no funding, financial relationships, or conflicts
of interest to disclose.
Send correspondence to Adrian L. James, DM, FRCS(ORL-HNS),
Department of Otolaryngology–Head and Neck Surgery, Hospital for
Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8,
Canada. E-mail: [email protected]
DOI: 10.1002/lary.23203
Laryngoscope 122: May 2012
cholesteatoma) predisposes to further infective and destructive consequences within and occasionally beyond the
temporal bone. Ossicular erosion and cholesteatoma are relatively rare consequences, and are therefore hard to predict
in most cases of TM retraction.2 Also unpredictably, some
TM retractions resolve spontaneously.2,3 These variable
outcomes make careful observation and monitoring an important part of the management of TM retraction. Several
staging systems have been developed and are widely used
for this purpose.2,4–6 However, there have been few
attempts to validate these systems by making repeated
assessments with the same or multiple observers,7 which is
of concern because many characteristics of these systems
have the potential to interfere with their reliability. For
example, subjective criteria, such as extent of bone erosion
in pars flaccida retraction (Tos stage 3 vs. 44) or depth of
pars tensa retraction (Erasmus stage 3 vs. 46), may be
prone to variability in interpretation, as may assessment of
adherence of the TM to the promontory (Sade stage 3 vs.
42). Alternative interpretations have lead to changes in the
descriptions of some systems.8,9 Such discrepancies, coupled
with limitations in accuracy of recall by the observer,10 may
also confound reliability. Furthermore, consensus on correlation between stage of retraction and disease process or
hearing threshold has not been established.6
James et al.: Evaluation of Ear Drum Retraction
1115
Although endoscopy does not allow depth perception
as readily as the stereoscopic view from a microscope,
otoendoscopic images are now commonly used to record
and monitor TM retraction. The validity of applying conventional staging systems to such images has not been
widely assessed. To determine an optimal system for
clinical and research classification of TM retraction on
endoscopic TM images, we assessed the validity of existing systems2,4,6 and compared them with audiometric
measures. Analysis of these findings and additional
descriptors of TM retraction were used to identify reliable and clinically useful indicators for management of
TM retraction. The study sample was selected from a
consecutive series of children with cleft palate to provide
a clinically representative range of TM retraction severity from a population at increased risk of retraction.
Approval for this study was granted by the hospital’s
research ethics board.
MATERIALS AND METHODS
Children with cleft palate have a routine multidisciplinary
review at our regional cleft palate referral center at approximately five yearly intervals following repair of their cleft at
around 1 year of age. A consecutive cross-sectional sample of
143 children attending this clinic over the course of a year was
selected for this study. All patients received a pure-tone audiogram and digital photography of both TMs with a 0 4-mm or
2.7-mm otoendoscope, after microsuction of meatal wax and keratin debris if necessary. The otoendoscope was positioned and
focused to include a close-up view of the entire TM if possible.
Images were displayed on a dedicated PC with an image capture card and stored on a hard disk drive for later retrieval.
Demographic details of each patient were collected. Ears with
tympanostomy tubes in situ, TM perforation, or a history of any
other surgery to the TM were excluded.
Each ear was assigned a random study number, and the
TM image was stored for viewing on a computer monitor. The
complete series was reviewed by an experienced pediatric otologist and dichotomized into two groups: A) those with clearly
normal and B) those with questionable or certain retraction.
Images of ears with concomitant conductive hearing loss from
group A, plus a random sample of around 20% of the remaining
normal images from group A, were combined with those from
group B to comprise a study sample for further assessment.
This study sample was assessed on two separate occasions by
six otolaryngologists with an interest in otology (two otologists,
two pediatric otologists, and two pediatric otolaryngologists, all
fellowship trained). All assessments were blinded to hearing
and demographic details. The TMs were assigned to a stage of
retraction with the systems developed by Sade2,8 and the Erasmus group6 for the pars tensa, and Tos for the pars flaccida.4 A
modified version of the Sade system was used for this study,
because the sole distinguishing factor in the original description
between Sade stages 3 and 4 is whether the TM retraction is
adherent. This important dynamic distinction cannot be made
with a single endoscopic image. Therefore, a later modification
of the staging system was used based on diagrammatic representation of stage 4, in which the TM is retracted more deeply
to line the mesotympanum.8 A copy of the illustrations and
descriptions was provided to the observers on both occasions to
reduce error from misapplication of the systems. A value of zero
was given in the absence of any visible retraction.
Following analysis of these findings, a list of characteristics of pars tensa retraction was compiled in an attempt to
Laryngoscope 122: May 2012
1116
identify more clinically relevant features of retraction that
could be assessed reliably. Six observers twice reinspected a
subset of 43 TMs representing the range of retractions in the
larger sample and rated the pars tensa according to these criteria: (0) normal; (1a) retraction, no contact to middle ear
structures; (1b) retraction touching promontory; (2a) retraction
touching incus; (2b) retraction enveloping incus; (3a) retraction
eroding incus (partial); (3b) retraction eroding incus (complete);
(4) retraction disappears out of site; (5) keratin accumulation
medial to annulus (potentially removable permeatus); (6) granulation tissue at retraction; (7) cholesteatoma (keratin
accumulation that cannot be cleaned permeatus).
The intra- and interobserver reliability for each staging
systems was the primary outcome measure, which was determined by calculating the kappa statistic. The kappa statistic
values were interpreted for reliability using the criteria
described by Landis and Koch.11 The mean degree of hearing
loss for each stage of each system was then calculated using the
mode average stage for the samples. Hearing loss was defined
as a mean four-tone average air-bone gap (ABG)12 of >25 dB
HL. Data from ears with middle ear effusion were excluded. For
the purposes of this analysis, a retracted TM was defined as a
staging score above zero by three or more observers on one or
more occasions. The Spearman rank order correlation was then
used to compare the hearing threshold and stages to explore
any significant differences in hearing between stages.
RESULTS
The median age of the 143 children reviewed was
13 years (range, 4–18 years). There were 41 ears
excluded for having a perforation (eight), tympanostomy
tube in situ (21), previous tympanoplasty or tympanomastoidectomy (three), or unclear photograph of the
pars tensa (nine), giving a total sample of 245 ears. Of
these, 76 (31%) were found to have a retraction of pars
tensa. The rate of pars flaccida retraction was similar at
73 ears (32%) in which the pars flaccida was adequately
photographed. A total of 137 (56%) had no sign of retraction. The extent of retraction according to each staging
system is shown in Table I.
Reliability of Retraction Assessment
Table II outlines the inter- and intraobserver agreement of the different systems for assessing the extent of
TM retraction. It can be seen that the pars tensa systems were more reliable than the system used for pars
flaccida retraction. Kappa scores were similar for the
Erasmus and Sade systems for assessing extent of pars
tensa retraction, although results for the latter are categorized more favorably as showing moderate agreement.
The multicomponent characterization of retraction outlined in the Materials and Methods section was applied
to a subset of the TM images, therefore the findings are
not directly comparable, but it does give substantial
agreement between observers.
TM Retraction and Hearing Loss
After excluding six ears with middle ear effusions,
nine of 72 (13%) pars tensa retractions were found to be
associated with conductive hearing loss (ABG >25 dB
HL), compared with seven of 71 (10%) pars flaccida
James et al.: Evaluation of Ear Drum Retraction
TABLE I.
Severity of Retractions by Staging System.
Pars Tensa
Multicomponent*
Pars Tensa
Sade8
Pars Tensa
Erasmus6
Pars
Flaccida
Tos4
0
169
169
169
158
1
32
34
32
38
1b
2
13
9
—
9
—
13
—
21
Stage
2b
2
—
—
—
3
3b
3
2
23
—
18
—
10
—
4
7
6
8
4
5
6
4
3
—
—
5
—
—
—
1
4
5
—
0
245
0
245
0
245
14
245
Cholesteatoma
Not visible
Total
Ears with middle ear effusions are included.
*See the Materials and Methods section for a description of the multicomponent characterization of retraction.
retractions (P ¼ 0.05; v2 test). It can be seen in Figure 1
that the severity of hearing loss generally increases with
the extent of retraction with all three staging systems.
However, there was no significant difference between adjacent stages in any system except between Erasmus
stages 1 and 2 (i.e., retraction not in contact with middle
ear structures vs. retraction in contact with promontory)
(P < .001; Spearman rank order correlation).
Analysis of the different characteristics of pars
tensa retraction in relation to hearing loss showed that
retraction onto the promontory alone (11 ears) was associated with a hearing loss of 30 dB (mean ABG),
retraction onto the incus and promontory (seven ears) a
loss of 18 dB, and onto the incus alone (eight ears) a loss
of 17dB. The hearing loss with retraction on to the
promontory alone was significantly worse than when the
TM was in contact with the incus (P ¼ 0.02; one-way
analysis of variance). The number of ears with other
characteristics of retractions was too small to make further subgroup analysis appropriate.
DISCUSSION
Classification systems for assessing the extent of
TM retraction do not appear to be very reliable when
applied to endoscopic images. Intra- and interobserver
assessment is only slight to fair for pars flaccida retraction, and fair to moderate for retraction of the pars
tensa. Even though such systems are widely used, they
have not been extensively validated for use with conventional otoscopy, microscopy, or otoendoscopy. One
previous report has documented unsatisfactory interobserver agreement for the Sade2 and Tos4 classifications
using selected images of TM retraction and a large number of observers with varying experience levels.7 In the
current study, levels of agreement remained suboptimal
despite the specialist interest of the observers. A contributing factor is likely to be the limitation of assessment
of the depth of retraction with a static two-dimensional
endoscopic image compared to the dynamic, or especially
microscopic, view available during clinical practice.13
Limitations in the design of the classifications that may
contribute are discussed below.
In addition to this lack of reliability, the clinical
relevance of these systems is limited by the lack of any
direct correlation with priorities in management, namely
to 1) prevent suppurative complications from cholesteatoma; 2) treat erosive complications, most commonly
permanent conductive hearing loss; 3) prevent erosive
complications; 4) treat hearing loss; and 5) prevent hearing loss. Hearing threshold is more important to the
patient than the appearance of their TM and must be
included as part of the assessment of any retraction.
The only feature of retraction noted to be associated
with significant hearing loss was retraction onto the
promontory alone, not touching the incus. This is represented by Erasmus stage 2. A further limitation of the
Sade and Erasmus systems is that three separate states
of retraction (onto incus alone, promontory alone, or
both incus and promontory) are grouped into two stages;
(i.e., Sade: [2] incus alone, [3] promontory with or without incus; Erasmus: [2] promontory alone, [3] incus with
or without promontory). Although not relevant to hearing, justification for the lower ranking of isolated
promontory retraction in the Erasmus system can be
given by greater risk of permanent hearing loss from ossicular erosion or cholesteatoma development from
posterosuperior retraction than from central TM retraction. Finally, neither system allows monitoring of small
changes in extent of depth, size, adherence, or bone erosion, which further limits their usefulness. Small
differences can be seen and potentially monitored more
readily with serial endoscopic images.
TABLE II.
Inter- and Intraobserver Agreement for Repeated Assessments of Tympanic Membrane Retraction Using Different Staging Systems.
Interobserver Agreement
Intraobserver Agreement
Kappa
Agreement
P Value
Kappa
Agreement
P Value
Pars flaccida, Tos
0.18
Slight
<.001
0.30
Fair
<.001
Pars tensa, Erasmus6
0.35
Fair
<.001
0.37
Fair
<.001
Pars tensa, Sade8
Pars tensa, multicomponent*
0.41
0.78
Moderate
Substantial
<.001
<.001
0.35
0.5
Moderate
Fair
<.001
<.001
Staging System
4
Level of agreement as defined by Landis and Koch.11
*The multicomponent characterization is described in the Materials and Methods section.
Laryngoscope 122: May 2012
James et al.: Evaluation of Ear Drum Retraction
1117
Fig. 1. Box plots of hearing loss versus stage of retraction for the Sade and Erasmus classifications of pars tensa retraction and Tos classification of pars flaccida retraction. No significant difference in hearing between stages, except Erasmus stage 1 and 2 (Spearman rank
order correlation). ABG ¼ air-bone gap.
The importance of adherence of a retracted tympanic membrane to middle ear structures is recognized
in the classification proposed by Sade.2 Observation of a
single image per TM did not allow assessment of adherence in this study. Even in the clinical setting, this
characteristic can be difficult to assess reliably, especially in children as cooperation can be limited. The
clinical significance, and indeed validity of assessment of
adherence, might depend on the method of assessment
(Siegel speculum, Valsalva maneuver, insufflation by nitrous oxide anesthesia [the necessary duration of which
will vary according to pneumatization14] or ease of surgical dissection at tympanoplasty). The significance of this
finding may also depend on whether the retracted segment is partially or totally adherent to the promontory
and/or incus. Finally, as demonstrated in Figure 2, the
prognostic significance of adherence remains unclear, as
retractions that had formerly appeared adherent may
subsequently lateralize spontaneously.
This study concentrated on assessment of pars
tensa retraction, because that causes the majority of
acquired pediatric cholesteatoma in our practice15 and
others.16 In addition to assessing the validity of currently used staging systems, we studied other
characteristics of TM retraction that might indicate
deterioration, based on the clinical imperative to intervene before ossicular erosion occurs to optimize the
chance of maintaining good hearing.1,15 The extent to
which the retraction involved the long process of incus
(touching/enveloping/eroding/complete
erosion)
was
hypothesized to be important for monitoring the progression to permanent hearing loss. Factors that might be
considered more immediate precursors of cholesteatoma
(granulation tissue/keratin accumulation), which could
be termed precholesteatoma, were also noted. Although
substantial agreement was achieved on interpretation of
these characteristics, the study was not adequately powered for subgroup analysis of their effect on hearing.
Fig. 2. Otoendoscopic images of the right tympanic membrane of child with tympanic membrane retraction. (a) Pars tensa retraction
appearing adherent to promontory, long process of incus, capitulum of the stapes and stapedius tendon. The long process of incus is partially eroded. (b) Same ear 10 months later showing lateralization of the tympanic membrane. The formerly retracted segment is now only
in contact with the long process of incus. This improvement occurred spontaneously, without treatment.
Laryngoscope 122: May 2012
1118
James et al.: Evaluation of Ear Drum Retraction
TABLE III.
Proposed Factors for the Assessment of Tympanic Membrane
Retraction in Relation to the Planning of Reconstructive Surgery.
Retraction with no keratin accumulation; normal hearing
No boney contact in ME
Retraction touching promontory
Retraction touching incus
Retraction touching stapes
Whole surface of retraction not visible
Retraction with impairment of keratin migration;* normal hearing
Keratin trail on adjacent canal wall or drum
Dry sheet or crust in retraction pocket
Moist keratin or granulation tissue in pocket
Retraction causing or contributing to ABG; no keratin
accumulation
Intact ossicular chain†
Long process incus eroded (partial or complete)
Stapes crus erosion (with or without incus erosion)
Retraction with associated ABG and impaired keratin migration
Cholesteatoma (i.e., uncleanable accumulation of
desquamated keratin)
*Keratin deposit can be removed completely without surgical
intervention.
†
May not be ascertainable without surgical exploration.
ME ¼ middle ear; ABG ¼ air-bone gap.
We conclude that monitoring of TM retraction for
guidance in timing of surgical management cannot be
made with simple staging systems applied to endoscopic
images of TM retraction and question whether these systems are significantly more valid when used with
microscopy. Similarly, drawing of TM retractions has
been shown to be unreliable.17 For individual patients,
comparison of serial otoscopic images is likely to be a
more reliable monitoring system to indicate progression
or resolution of retraction (D Pothier, personal communication, thesis in preparation). For the purposes of
guiding timing of TM reconstruction, a simple approach
is proposed based on the detection of keratin accumulation and hearing loss. These are the important factors
that influence surgical decision making.18 It is hypothesized that surgical reconstruction for TM retraction is
more strongly indicated when keratin migration becomes
impaired, increases more so if hearing loss occurs, and
more still if both occur, hence the four retraction groups
shown in Table III. A distinction must be made between
accumulation of desquamated keratin, which can be
cleaned from a retraction completely (in clinic or even
under anesthesia), and cholesteatoma, in which the
accumulated keratin cannot be removed without surgery.
It has been proposed that cholesteatoma be added as the
ultimate stage of the retraction process6 and is listed
here for that reason, although the addition is somewhat
superfluous when considering retraction management,
as cholesteatoma is a separate entity.
Classification systems with multiple stages become
too cumbersome for routine use, but on the basis of experience from this study, additional potential subgroups
are listed in Table III as suggestions for future research.
Although they may be indicators of clinical severity, our
Laryngoscope 122: May 2012
findings suggest it may not be possible to assess them
reliably. Ossicular erosion is included in accordance with
previous recommendations.12 Even though the current
study shows retraction onto the promontory is associated
with worse hearing than onto the incus, ossicular disruption is considered more likely to cause persistent hearing
loss after spontaneous or surgical lateralization of the
TM. Large and longitudinal studies would be required to
validate the reliability and prognostic significance of all
these subgroups. The difficulty clinicians have in accurate recollection of existing four-stage systems10 indicates
that a system with more components could not be implemented reliably in standard clinical practice. However, in
this research setting where details of the systems were
available for reference, we found multicomponent assessment very feasible with good inter- and intraobserver
reliability. Clearly, the decision to offer reconstructive TM
surgery cannot be based on such a classification alone,
but must also take into account the status of the contralateral ear and other patient factors.
Reliability of assessment of pars flaccida retraction
was much more susceptible to intra- and interobserver
variability than assessment of the extent of pars tensa
retraction. The subtle difference between a normal and
slightly retracted pars flaccida and the subjective assessment of extent of scutum erosion are considered to be
the principal limitations. We do not consider that clinical
assessment with an otoscope or microscope would make
these judgments any more reliable than with an endoscopic image. The absence of any correlation between
stage of retraction and hearing loss is less surprising
than with pars tensa retraction given its smaller role in
hearing function. Our cross-sectional study design does
not make it possible to determine whether any prognostic significance can be attached to this scale. Further
characterization of pars flaccida retraction assessment
would appear to be warranted.
Children with cleft palate were selected for this
study because of the greater prevalence of tympanic
membrane retraction in this population. Nearly half of
the ears were found to have some degree of retraction,
compared with retraction rates in a normal pediatric
population of around 6% pars tensa and 8% pars flaccida.19 The consecutive cross-sectional sample from a
cleft palate clinic should provide a less-skewed representation of the severity of TM retraction in the normal
population than sampling of an otologic clinic, in which
severe retractions would likely be overrepresented. As
only a small proportion of our sample had conductive
hearing loss, investigation of a population with known
retraction would facilitate investigation of the association between retraction and hearing loss. The staging
systems evaluated in this study were not developed specifically for children with cleft palate. It is conceivable
that the nature of TM retraction may differ in other populations so as to render our observations less applicable.
CONCLUSION
The reliability of staging systems for tympanic
membrane retraction in current use is unsatisfactory
James et al.: Evaluation of Ear Drum Retraction
1119
when applied to endoscopic images. The different stages
do not allow monitoring of small changes in extent of retraction, or provide adequate distinction between factors
associated with conductive hearing loss, ossicular erosion, or early formation of cholesteatoma. More reliable
and clinically relevant measures of TM retraction are
required.
Acknowledgments
The authors are grateful to Homira Osman and
Andrea K. Suthakaran for entering audiometric data.
BIBLIOGRAPHY
1. Borgstein J, Gerritsma TV, Bruce IA. Erosion of the incus in pediatric posterior tympanic membrane retraction pockets without cholesteatoma.
Int J Pediatr Otorhinolaryngol 2008;72:1419–1423.
2. Sade J, Avraham S, Brown M. Atelectasis, retraction pockets and cholesteatoma. Acta Otolaryngol 1981;92:501–512.
3. Pars tensa and pars flaccida retractions in persistent otitis media with
effusion. Otol Neurotol 2001;22:291–298.
4. Tos M, Poulsen G. Attic retractions following secretory otitis. Acta Otolaryngol 1980;89:479–486.
5. Charachon R, Gratacap B, Vuarnet J. Classification and surgical treatment of fibroadhesive otitis. Am J Otol 1985;6:305–310.
6. 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 2007;117:1255–1259.
7. Pothier DD. The Sade and Tos staging systems: not adequately reliable
methods of staging retraction of the tympanic membrane? Clin Otolaryngol 2009;34:506–507.
Laryngoscope 122: May 2012
1120
8. Sade J, Ar A. Middle ear and auditory tube: middle ear clearance, gas
exchange, and pressure regulation. Otolaryngol Head Neck Surg 1997;
116:499–524.
9. Sade J, Amos AR. The Eustachian tube. In: Ludman H, Wright T, eds. Diseases of the Ear. London: Arnold; 1998:334–352.
10. Pothier DD, Cooke C, Ahmed SB. Limited knowledge and recall of common
staging systems: can we rely on what the clinical record tells us about
retraction of the tympanic membrane? Clin Otolaryngol 2009;34:274.
11. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–174.
12. Committee on Hearing and Equilibrium guidelines for the evaluation of
results of treatment of conductive hearing loss. American Academy of
Otolaryngology–Head and Neck Surgery Foundation, Inc. Otolaryngol
Head Neck Surg 1995;113:186–187.
13. Bhutta MF, Haggard M. Re: The Sade and Tos staging systems: not
adequately reliable methods of staging retraction of the tympanic membrane? Clin Otolaryngol 2010;35:68; author reply 69.
14. Alper CM, Kitsko DJ, Swarts JD, et al. Role of the mastoid in middle ear
pressure regulation. Laryngoscope 2011;121:404–408.
15. James AL. Hearing preservation in pediatric cholesteatoma surgery. Paper
presented at: 37th Annual Meeting of the Society for Ear, Nose and
Throat Advances in Children (SENTAC), December 3–6, 2009, in Salt
Lake City, UT. Audio-Digest Otolaryngology: Advances in the Treatment
of Children. Available at: http://www.audio-digest.org/pages/htmlos/
35152.2.6868546997516489959. Accessed January 20, 2012.
16. Hamilton J, Rhagava N. Comparison of the characteristics of cholesteatoma at the time of surgery in children and adults. In: Ozgirgin ON, ed.
Surgery of the Ear–Current Topics. Antalya, Turkey: Rekmay; 2009:
187–188.
17. Pothier DD, Awad Z. Can we accurately interpret drawings of ears with
retractions? Clin Otolaryngol 2007;32:42–46.
18. Luntz M, Avraham S, Sade J. The surgical treatment of atelectatic ears
and retraction pockets in children and adults. Eur Arch Otorhinolaryngol 1991;248:400–401.
19. 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 2011;32:1256–1261.
James et al.: Evaluation of Ear Drum Retraction