Key points:
- To compare the hearing performance between the two myringoplasties,
microscopic and endoscopic, and between full-thickness- and
partial-thickness tragal cartilage graft (FTTC and PTTC, respectively)
in endoscopic myringoplasty.
- Hearing improvement was achieved irrespective of the preoperative
tympanic perforation size and the malleus handle exposure status in
the FTTC group.
- The postoperative air-bone gap was comparable in the temporalis fascia
and PTTC groups
- The audiological improvement at 250 Hz was better in the FTTC group
than in the PTTC group.
- Good hearing performance was achieved after myringoplasty with FTTC,
irrespective of the preoperative perforation size and malleus handle
exposure status.
Introduction
Endoscopic myringoplasty has gained popularity in recent years, as its
use can help to achieve a clear surgical vision,1 less
postoperative pain, and a high success rate both in anatomy and
function.2 Full-thickness tragal cartilage (FTTC) is
the grafting material of choice for endoscopic
myringoplasty.3,4 FTTC is easy to harvest and suitable
for one-handed operations under the endoscope due to its hardness.
However, there is a considerable difference in the thickness, stiffness,
and elasticity between FTTC and the natural tympanic membrane. Many
otologists doubt its postoperative hearing performance. Performing
myringoplasty under the microscope with a temporalis fascia (TF) graft
is the classic surgical approach. However, in endoscopic myringoplasty,
partial-thickness tragal cartilage (PTTC) is used as a graft, which is
closer to the natural tympanic membrane. Here, we aimed to compare the
hearing performance between the two myringoplasties, microscopic and
endoscopic, and between FTTC and PTTC graft in endoscopic myringoplasty.
We also compared the postoperative audiological performance between
them.
Materials and Methods
Subjects
This retrospective cohort study
was conducted at the Department of Otolaryngology of a tertiary hospital
in China between January 2017 and February 2020. Adult patients
(>18 years) with chronic otitis media, persistent tympanic
membrane perforation, an intact ossicular chain on computed tomography
scan, and ossicular chain mobility during the intraoperative assessment
were included. Hearing performance in microscopic and endoscopic
myringoplasties, each using a different graft, was compared. For the
FTTC group, cartilage with no thinning and perichondrium on one side was
used; the myringoplasty was performed under the endoscope. For the TF
group, traditional myringoplasty was performed under the microscope
using TF as a graft. For the PTTC group, ultra-thin tragal cartilage was
used and the myringoplasty was performed under the endoscope.
Postoperative tympanum closure rate and hearing performance were
evaluated 3 months after the operation.
The study protocol was approved by
the Ethics Committee of the Hospital.
Definitions of variables
The mean air-bone gap (ABG) was the average ABG value at 500 Hz, 1000
Hz, 2000 Hz, and 4000 Hz. The mean ABG was divided into four categories:
1) ≤10 dB, 2) 11–20 dB, 3) 21–30 dB, 4) ≥31 dB. Three factors
affecting the ABG were included in this study: time (before and after
surgery), tympanic perforation size (large [≥50%] and small
[<50%]), and exposure of malleus handle (exposed and
unexposed).
Statistical analysis
Continuous variables were presented as mean ± standard deviation for
normally distributed variables and as median (interquartile range) for
variables that followed a non-parametric distribution. Categorical
variables were compared using the chi-square test. Quantitative
continuous variables were compared using the unpaired Student’st -test or the Mann-Whitney U test for normally and non-normally
distributed variables, respectively. The factors affecting ABG were
compared using the general linear model repeated measures test.
Propensity score matching (PSM)
was performed to balance the baseline characteristics between the TF
group and the FTTC group. Age, gender, size of perforation, exposure of
malleus handle, and ABG values at frequencies from 250 Hz to 4000 Hz
before surgery were matched. Before PSM, there were 40 patients in the
microscopic group and 111 patients in the endoscopic group. However,
after the cohorts were propensity score-matched to create a 1:1 matched
set using a caliper width of 0.02; a total of 38 patients were included
in each group. After the two groups were matched, the distribution of
the ABG values for frequencies of 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, and
4000 Hz did not obey normal distribution; therefore, a non-parametric
test, to compare two-related-samples, was used for analysis.
P -values < .05 was considered statistically
significant. IBM SPSS for Windows version 22.0 (IBM Corp., Armonk, NY,
USA) was used for analyses.
Myringoplasty procedure
After infiltration of the canal
with local anesthesia, the edges of the perforation were freshened. A
broad tympanomeatal flap was
elevated from 11 to 6 o’clock (left ear) and the middle ear cavity was
entered; care was taken to preserve the chorda tympani nerve. The
ossicular chain was palpated and its mobility was confirmed. The
tympanic mucosa, anterior space of malleus, anterior and posterior
tympanic isthmus, and eustachian tube orifice were explored. FTTC was
harvested with perichondrium on one side, and
a ”V” shaped notch was
made. The epithelium on the
malleus handle was removed, and the FTTC was inserted
between the malleus handle and the
tympanum, with the perichondrium facing outward. The ”V” shape was
embedded in the short process of the malleus. The graft was supported
with gelatin sponges soaked in normal saline. A zero-degree endoscope
(diameter, 3 mm; length, 140 mm) was used under an endoscope monitoring
system (Storz TC200, Germany).
In the TF group, a classic microscopic myringoplasty was performed
through postauricular and transcanal approaches utilizing the TF for
reconstruction. The graft was placed under the malleus handle.
In the PTTC group, endoscopic myringoplasty was performed utilizing
ultra-thin tragus cartilage with a perichondrium layer as the graft,
which was placed under the malleus handle.5
Results
Myringoplasty with FTTC graft: Factors affecting the mean
ABG and its trend
The average thickness of the FTTC was 0.850 ± 0.117 mm (range,
0.642–1.083 mm). The mean operation time was 52.44 ± 14.04 minutes, and
the average postoperative dry ear time was 3.457 ± 1.78 weeks. The
tympanic membrane integrity was restored in 91% of the cases. Figure 1
presents key images before, during, and after surgery. A mean ABG of
12.17 ± 6.58 dB was observed postoperatively (≤10 dB, 45%; 11–20 dB,
45.9%; 21–30 dB, 7.2%; ≥31 dB, 1.8%; Figure 2A.)
Further, the impact of the factors affecting ABG was explored. The
factors assessed before and after surgical intervention were perforation
size and malleus handle exposure status. The mean ABG changed
significantly after surgical intervention (F(1,108) =
38.707, P < .001). The tympanic perforation size and
malleus handle exposure status significantly affected the mean
preoperative ABG (F(1,108) = 5.969, P = .016;
F(1,108) = 7.281, P = .008, respectively).
Further, no interaction was found between surgical intervention and
perforation size (F(1,108) = 1.022, P = .314) and
between surgical intervention and malleus handle exposure status
(F(1,108) = 0.053, P = .818). To summarize these
findings, the perforation size and malleus handle exposure status did
not affect the ABG trend (change in the ABG values before and after
surgery). The distribution of mean ABG under different factors is
presented in Figure 2B.
Comparison of audiological performance betweenTF and FTTC groups