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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 26  |  Issue : 4  |  Page : 215-220

Reliability of preoperative gel foam patch test in predicting postoperative hearing outcome


Department of ENT, Dr. Baba Saheb Ambedkar Central Railway Hospital, Mumbai, Maharashtra, India

Date of Submission22-Jul-2020
Date of Decision24-Jul-2020
Date of Acceptance02-Aug-2020
Date of Web Publication23-Apr-2021

Correspondence Address:
Dr. Deepak Dalmia
Department of ENT, Dr. Baba Saheb Ambedkar Central Railway Hospital, Byculla, Mumbai - 400 027, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_157_20

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  Abstract 


Aim: This study aims to know the correlation between the preoperative gel foam patch test with the postoperative hearing outcome. Objectives: The objective is to correlate and compare the air-bone gap (ABG) and mean hearing thresholds obtained at frequencies 500 Hz, 1 KHz, 2 KHz, and 4 KHz through audiological evaluation preoperatively, immediately after gelfoam application and 2 months postoperatively (Type I tympanoplasty). Materials and Methods: A total of 124 cases with a mean age of 37 years with a history of chronic otitis media (COM, mucosal type) having medium to large size of central perforation of the tympanic membrane with pure conductive hearing loss participated in this study. Cases were subjected to routine investigations along with a battery of otological investigations. Further, pure-tone audiometric evaluation was performed before gelfoam patch application, immediately after gelfoam patch application and postoperatively after 2 months and the outcomes were compared. Results: Across all four frequencies, ABG was improved and showed a highly significant difference between preoperative mean findings in comparison to patch and postoperative findings. In this study, a strong positive correlation and reliability between patch test hearing thresholds and postoperative hearing thresholds are observed. Comparing preoperative hearing thresholds and postoperative hearing thresholds with student t-test thresholds improved by approx 17 dB hearing loss (17.50645). Conclusion: Hence, this study shows preoperative gel foam patch test in cases of pure conductive hearing loss is reliable in predicting the postoperative hearing outcome. Furthermore helps in convincing and counseling the patients.

Keywords: Air-bone gap, chronic otitis media, gelfoam patch test, tympanoplasty


How to cite this article:
Dalmia D, Kamble SS, Katakdhond HN, Davange N, Patni P, Bhagavan K. Reliability of preoperative gel foam patch test in predicting postoperative hearing outcome. Indian J Otol 2020;26:215-20

How to cite this URL:
Dalmia D, Kamble SS, Katakdhond HN, Davange N, Patni P, Bhagavan K. Reliability of preoperative gel foam patch test in predicting postoperative hearing outcome. Indian J Otol [serial online] 2020 [cited 2021 Jun 16];26:215-20. Available from: https://www.indianjotol.org/text.asp?2020/26/4/215/314340




  Introduction Top


One of the most common problems in otology is chronic tympanic membrane (TM) perforation.[1] It is either due to otitis media or trauma and presents clinically with conductive hearing loss and chronic infection.[2] The treatment of choice for chronic TM perforation is tympanoplasty. The success of tympanoplasty depends on the various factors such as surgeon experience, graft material, proper selection of case, and preoperative assessment. The patch test is one of the preoperative tests to know the hearing outcome. The patch test involves covering the TM perforation with a small piece of patching material and performing an audiological (audiometric) evaluation to know the hearing outcome. Different patching materials are available such as carbon paper,[3] cigarette paper,[3] aluminum foil,[4] and gel foam.[5] Patch test gives an idea about the continuity of ossicular status and helps in planning the surgery.[6] As very few studies are available in the literature, we conducted this study to know the correlation between the preoperative gel foam patch test with the postoperative hearing outcome and add data to the literature.


  Materials and Methods Top


Initially, 155 cases were observed, but 31 cases were rejected due to middle ear pathologies or corrections, and total 124 cases between the age group of 20–50 years of chronic otitis media (COM, mucosal type) having medium to large size of central perforation of the TM participated in this study.

Inclusion criteria

  1. Pure conductive hearing loss
  2. Inactive COM for more than 3 months
  3. Age group between 20 and 50 years
  4. Patients with intraoperative finding as to the intact and mobile ossicular chain
  5. Patent and functioning Eustachian tube (ET)
  6. The medium and large central perforation.


Exclusion criteria

  1. Mixed and sensorineural hearing loss
  2. Active COM
  3. Age <20 years and above 50 years
  4. Patients with intraoperative finding as ossicular fixation or discontinuity
  5. Abnormal ET
  6. Squamosal type of otitis media
  7. Small central perforation
  8. Revision cases.


Instruments used

Pure tone audiometry was conducted in a sound-treated room according to ANSI 1969 Standards. The audiometer details are as follows:

  • Audiometer – One and half channel audiometer, Elkon eda 3N3
  • Standard supra-aural headphones
  • BC vibrator
  • Resonance rm 30 impedance audiometer.


The present study aimed to know the correlation between the Preoperative Gel foam Patch test and its postoperative hearing outcome. Institutional Ethical Committee approval was taken. After taking written informed consent, detailed case history and examination were done. The relevant details were recorded, and cases were then subjected to routine investigations along with a battery of otological investigations as follows:

  1. Otomicroscopy to confirm the otoscopic findings and select cases as per the inclusion criteria. The size of the perforation was determined using a right-angle otologic hook and was graded as small (3 mm), medium (3–5 mm), and large (5 mm but not exceeding 10 mm)
  2. Audiological evaluation:


Preoperative hearing evaluation

Pure-tone audiometry (PTA) was done to confirm tuning-fork test findings and to obtain baseline air conduction (AC) thresholds, bone conduction (BC) thresholds, and air-bone gap (ABG). PTA also helped to exclude patients with mixed or sensorineural hearing loss. AC thresholds were measured by taking the average threshold of speech frequencies, i.e., mean of the hearing threshold at 0.5, 1, 2, 4 Kilohertz (kHz). BC thresholds were measured for 0.5, 1, 2, and 4 Kilohertz (kHz). Average thresholds of speech frequencies above normal levels are a measure of the degree and type of hearing impairment. Masked PTA was done if there was a difference of more than 40 dB between AC threshold of the test ear and the BC threshold of the opposite ear or when the ABG of the poorer ear under test was more than 10 dB. The resulting levels were expressed in dB hearing loss.

Patch test

Depending on the size of perforation slightly large Gel foam (impregnated with medicated drops) was used to plug the perforation under aseptic conditions. The gel foam was placed by a single senior surgeon on an outpatient department (OPD) basis. Then, patch test findings AC threshold was recorded, AB gap calculated and an average of speech frequencies 0.5, 1, 2, 4 Kilohertz (kHz) was obtained.

The gel foam was removed by using Alligator forceps, and no medications were given.

Postoperative hearing evaluation

The patient subsequently underwent Type 1 tympanoplasty, and after 2 months, postoperative period repeat AC thresholds were recorded and ABG was calculated.

The PTA was performed for 500 Hz, 1 kHz, 2 kHz, and 4 kHz following ANSI Guidelines. We used these frequencies as they fall under speech frequency and used in calculating the PTA average.

Thus, in total, three audiological evaluations were done:

•Before Gelfoam patch application

•Immediately after Gelfoam patch application

•2 months after operation (Type 1 tympanoplasty).

Statistical analysis

SPSS 23.0 software (1BM, USA) was used for the statistical analysis. Pearson correlation coefficient test and Student's t-test are performed with a P = 0.05 level of significance.


  Results Top


In this study, a total of 124 patients had a conductive type of hearing loss. Patients with an age group of 20–50 years were included with a mean average age of 37 years. Thirty-four patients (6 females and 28 males) were in the age group of 20–30 years, while in 30–40 years age group, 44 patients were seen (21 males and 23 females), in 40–50 years age group, we had 46 patients (28 males and 18 females).

It was observed that 56 patients had left ear perforation (38 males and 18 females) and 68 patients had right ear perforations (39 males and 29 females). Thirty patients had large perforation and 94 patients had moderate perforation and small perforations were excluded from study. The results were tabulated in terms of hearing thresholds and differences in the ABG from preoperative hearing thresholds, patch hearing thresholds, and postoperative hearing thresholds and were analyzed on the SPSS software version 23.0. Based on the mean of ABG comparison is made between the preoperative difference in the ABG with the mean of the ABG in patch test and the difference of ABG postoperatively.

The mean ABG at each of the four frequencies improved in the study in comparison with a preoperative, patch test, and postoperative findings [Figure 1].
Figure 1: This graph represents the comparison of air bone gap mean in preoperative, patch test and postoperative status at each of the following frequencies: 500 Hz, 1KHz, 2KHz, and 4KHz

Click here to view


At 500 Hz, the mean preoperative findings for the study group was 34.3 dB with a mean of 20.6 dB in patch test, resulting in a 13.7 dB gain, while in postoperative findings, 17.5 dB gain was obtained.

This indicates that in comparison to preoperative findings, there is a significant difference in the ABG in the patch and postoperative findings. Reduction in ABG means improved hearing thresholds.

At 1 KHz, the mean preoperative findings were 37.0 dB with a mean of 24.2 dB in patch test, resulting in a 12.8 dB gain while in postoperative findings 17.2 dB gain, indicating a significant difference in the ABG.

Similarly, at 2 KHz, the mean preoperative findings were 38.6 dB with a mean of 22.9 dB in patch test, resulting in a 15.7 dB gain while in postoperative findings 17.6 dB gain, indicating a significant difference in ABG between preoperative findings. While patch and postoperative findings are approximately similar.

While at 4 KHz, the mean preoperative findings were 40.2 dB with a mean of 26.9 dB in patch test, resulting in a 13.3 dB gain, while in postoperative findings, mean 18.2 dB, indicating a significant difference in ABG between preoperative findings. While patch and postoperative findings are showing approximately similar.

Overall, across all four frequencies, it can be seen that ABG was improved and showed a highly significant difference between preoperative mean findings in comparison to patch and postoperative findings. While comparing ABG between preoperative and postoperative findings, all frequencies showed better improvement.

Comparing frequencies between the patch and postoperative findings, low frequencies (500 Hz and 1 kHz) showed a difference of 3–4 dB, whereas high frequencies (2 kHz–4 kHz) showed 2–3 dB difference in ABG.

In [Figure 2], mean of hearing thresholds is represented in y-axis and frequencies (500 Hz, 1KHz, 2KHz, and 4KHz) in X-axis. This shows preoperative hearing thresholds comparison with patch test hearing thresholds and postoperative hearing thresholds across all the four frequencies. This figure depicts that preoperative hearing thresholds are improved at all frequencies in patch test and better improvement is seen in postoperative hearing thresholds. It also shows improvement in postoperative hearing thresholds which is better than patch test hearing thresholds.
Figure 2: Comparison between the mean thresholds of preoperative, patch and postoperative hearing status

Click here to view


Further, results are correlated and calculated using the Pearson correlation test and Student's t-test in terms of significance.

We can see in [Table 1], there is notable difference between average of patch test hearing thresholds and postoperative hearing thresholds. The purpose of this test is to determine whether there is statistical evidence that the mean difference between paired observations on a particular outcome is significantly different from zero.
Table 1: Mean values of patch test hearing threshold and postoperative hearing thresholds

Click here to view


The results are presented in [Table 2] indicates that, there is strong positive correlation between patch test hearing thresholds and postoperative hearing thresholds. In [Table 2], the given P < 0.05 so we reject null hypothesis and conclude that there is a strong positive correlation between two variables.
Table 2: Correlation between patch test and postoperative hearing thresholds

Click here to view


From the [Table 3], the t-statistics 11.703, and P = 1.01 × E-21, which is very small, we can reject the null hypothesis since P < 0.05. There is strong evidence that treatment improved patient's hearing thresholds. In these data, it improved by 3–4 dB hearing loss (3.6218).
Table 3: Student t-test between patch test hearing thresholds and postoperative hearing thresholds

Click here to view


As shown in [Table 4], the relevant result for the paired t-test is in different color. From the highlighted row, the t statistics = 36.161, and P = 2.18 × E-67, which is very small, we can reject the null hypothesis since P < 0.05. There is strong evidence that treatment improved patients hearing thresholds. In the data, thresholds improved by approximately 17 dB hearing loss (17.50645).
Table 4: Student t-test between preoperative hearing thresholds and postoperative hearing thresholds

Click here to view


As shown in [Table 5], preoperatively 10 patients were having mild hearing loss, 70 patients were having moderate hearing loss, and 44 patients were having moderately severe hearing loss.
Table 5: Number of patients improved (n=124) w.r.t preoperative hearing thresholds, patch test hearing thresholds and postoperative hearing thresholds

Click here to view


In patch test, 10 patients with mild hearing loss shifted to normal hearing threshold, among 70 patients who had moderate hearing loss 69 patients hearing threshold shifted to mild hearing loss and 1 patient hearing threshold shifted to normal hearing threshold.

Postoperatively, among 44 patients who had moderately severe hearing loss, 30 patients hearing threshold was shifted to moderate hearing loss and 14 patients hearing threshold shifted to mild hearing loss.


  Discussion Top


There was a positive correlation between preoperative gel foam patch test and postoperative hearing outcome (P <.05) stating that the preoperative patch test predicts the hearing outcome. We measured success rate in terms of reliability of hearing outcome in between the patch test and postoperative findings. Cases with intraoperative findings such as ossicular discontinuity or tympanosclerosis were not included in the study.

Chronic TM perforation is the most common problem in otology presenting with conductive hearing loss, tympanoplasty is the treatment of choice. We conducted this study to know the importance of the patch test in predicting the postoperative hearing outcome, as very few studies are present in the previous literature. Patch test was initially described using the “paper Patch test” Schuknechnt, 1993a; Glasscock and Shambaugh, 1990. The principle behind the Paper Patch test is described as follows-the patch returns the pressure difference across the TM to near-normal levels. The patch does not return to normal any of the structural modifications made to the TM by the perforation, for example, disruption of fibers or changes in tension. It thus successfully improves hearing in many cases of perforated TMs. The pressure difference is the primary mechanism of hearing loss with perforation. It restores the pressure difference across the TM.[7] We have used gel foam in our study. Gel foam is a denatured porous gelatin sponge used almost by every otologic surgeon, as hemostatic and packing material. It is a nontoxic and nonallergic material. We used gel foam because of its sterile nature and easy availability to otologist. It completely occludes the perforation of medium and large size, and it does not fall into the middle ear and also it is easy to remove the gel foam from the perforation without causing damage to TM using suction or alligator forceps.

The sample included 124 patients with mucosal type COM cases. The left ear was affected in 56 patients, and the right ear was affected in 68 patients.

In our study, the mean average of the age group was 37 years, implying these were the group belonging to the working population and bearing the disease burden.

There were 77 male patients and 47 female patients; the male population was more because of the requirement of fitness for doing the duty in our institution.

Our study showed that there was significant improvement between the prepatch and patch test, the hearing threshold improved on placing the gel foam patch. The mean AB gaps were decreased and the mean hearing threshold improved by 12–15 dB across the four frequencies measured (500 Hz to 1000 Hz). There was also a significant improvement between preoperative and postoperative mean hearing thresholds by 17–18 dB. The mean hearing threshold gain between the patch test and postoperative findings was 2–5 dB as shown in [Figure 3].
Figure 3: Shows audiogram findings of 33 years male with history of ear discharge and decreased hearing since 8 years. Pre-operative findings indicate moderately severe conductive hearing loss, Patch and Postoperative findings indicates mild conductive hearing loss. Plotting in red color indicates pre-operative and post-operative hearing thresholds, green color indicates hearing thresholds with patch test

Click here to view


In conductive hearing loss, large size TM perforation can cause air bone gap up to 60 dBHL with normal BC thresholds and none of the cases included in the study had >60 dBHL hearing loss, hence up to moderate and moderately severe conductive loss were seen in our study.

As per literature, BC thresholds may be unaffected if the middle ear BC component is not significantly hindered. The resulting air-bone gaps can be as great as approximately 60 dB.[8]

This shows that the preoperative gel foam patch test can positively correlate the postoperative hearing outcome. This is congruent with the previous study done by Verma et al.,[9] which concluded that paper patch test audiological closure of the ABG in the range of 0–30 dB was achieved in 80% of cases. This is comparable to audiological closure following myringoplasty (88% achieved audiological closure of 0 30 dB). Hence, paper patch test is a useful tool to predict the likely hearing gain postoperative.

The mean ABG increased at all four frequencies. The effect was more prominent in lower frequencies 500 Hz and 1000 Hz (3–4 dB gain in hearing threshold) than higher frequencies 2000 Hz and 4000 Hz (1 dB gain). This is in accordance with various studies. A study by Dawood[10] concluded that the distribution of hearing thresholds across the speech frequencies (500, 1000, and 2000 Hz), showing largest mean postoperative AC hearing gain (23.01 dB) and ABG reduction (21.52 dB) at 500 Hz, almost comparable to the observation in other studies. Maroto et al.[11] assessed hearing improvement after myringoplasty in 119 cases and concluded that greater hearing improvement was found at a lower frequency with the best results at 250 Hz.

Similarly, Choi et al.[12] studied 559 chronic ear surgeries and found that the AC threshold and ABG improvement was detected primarily in the low and mid frequencies.

In the current study, the hearing gain was more in postoperative cases compared to the patch test. This could be explained as there will be a complete seal obtained postoperatively compared to the possibility of some leakage and due to immobility of gel foam during sound transmission.

The limitations in our study were belonging to its retrospective nature, other determinants of hearing outcome like middle ear volume were not taken into account, we did not include small perforations in our study, and our study does not give an idea about complex cases like Squamosal disease, Cholesteatoma, Revision surgery. Very few literatures were available pertaining to the study. More study has to be done regarding this topic and help in arriving at a concrete conclusion.


  Conclusion Top


Preoperative Gel foam patch test in cases of pure conductive hearing loss is reliable in predicting the postoperative hearing outcome. It is a nonexpensive OPD bases procedure that helps in predicting the postoperative hearing outcome. It also helps in convincing and counseling the patients and is of more help in counseling a case of bilateral large perforation and performing Gel foam patch test as patient experiences immediate improvement in hearing.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Gelfand S. Essentials of Audiology. 4th ed. New York: Thieme; 2016. p. 159.  Back to cited text no. 1
    
2.
Laidlaw DW, Costantino PD, Govindaraj S, Hiltzik DH, Catalano PJ. Tympanic membrane repair with a dermal allograft. Laryngoscope 2001;111:702-7.  Back to cited text no. 2
    
3.
Altuntaş EE, Sümer Z. Biocompatibility evaluation of cigarette and carbon papers used in repair of traumatic tympanic membrane perforations: Experimental study. Eur Arch Otorhinolaryngol 2013;270:81-6.  Back to cited text no. 3
    
4.
Santhi T, Rajan KV. A study of closure of tympanic membrane perforations by chemical cauterisation. Indian J Otolaryngol Head Neck Surg 2012;64:389-92.  Back to cited text no. 4
    
5.
Parparella MM, Shumrick D, Gluckman J, Meyerhoff W. Textbook Otolaryngology. Philadelphia, Pennsylvania: W. B. Saunders Co.; 1991. p. 1445.  Back to cited text no. 5
    
6.
Glasscock ME, Shambaugh GE. Surgery of the Ear. 4th ed. Philadelphia: Saunders; 1990.  Back to cited text no. 6
    
7.
Voss SE, Rosowski JJ, Merchant SN, Peake WT. Middle-ear function with tympanic-membrane perforations. I. Measurements and mechanisms. J Acoust Soc Am 2001;110:1432-44.  Back to cited text no. 7
    
8.
Katz J, Chasin M, English K, Hood L, Tillery K. Handbook of Clinical Audiology. 7th ed. USA: Lippincott Williams and Williams; 2014.  Back to cited text no. 8
    
9.
Verma S,Arora A, Narvey VP. Comparison of conventional temporalisfascia myringoplasty with fascia lata myringoplasty among patients with hearing loss. Int J Otorhinolaryngol Head Neck Surg 2019;5:926-31.  Back to cited text no. 9
    
10.
Dawood MR. Hearing evaluation after successful myringoplasty. J Otol 2017;12:192-7.  Back to cited text no. 10
    
11.
Maroto DP, Gutiérrez JJ, Jiménez MC, Rodríguez VP, Morente JC, Benítez-Parejo N. Functional results in myringoplasties. Acta Otorrinolaryngol Esp 2010;61:94-9.  Back to cited text no. 11
    
12.
Choi HG, Lee DH, Chang KH, Yeo SW, Yoon SH, Jun BC. Frequency-specific hearing results after surgery for chronic ear diseases. Clin Exp Otorhinolaryngol 2011;4:126-30.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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