|Year : 2020 | Volume
| Issue : 3 | Page : 186-190
The diagnostic value of tympanometric width in identifying middle ear disorders
Mohd Normani Zakaria1, Maziah Romli1, Wan Najibah Wan Mohamad1, Mahamad Almyzan Awang1, Noor Alaudin Abdul Wahab2
1 Department of Audiology and Speech Pathology, Audiology and Speech Pathology Programme, School of Health Sciences, Universiti Sains Malaysia, Kelantan, Malaysia
2 Department of Audiology and Speech Pathology, Audiology Programme, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia, Malaysia
|Date of Submission||27-Oct-2019|
|Date of Decision||18-May-2020|
|Date of Acceptance||14-Sep-2020|
|Date of Web Publication||22-Dec-2020|
Prof. Mohd Normani Zakaria
Audiology and Speech Pathology Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan
Source of Support: None, Conflict of Interest: None
Tympanometry is a valuable test to measure the mobility of the tympanic membrane and middle ear function in an objective manner. Clinically, the middle ear status is determined based on the tympanogram types derived from typical tympanometric parameters, including static admittance, tympanometric peak pressure , and ear canal volume. Nevertheless, a further tympanometric parameter, tympanometric width (TW), is not commonly used for hearing diagnosis. In this paper, we report a case demonstrating the superiority of TW in detecting middle ear disorders. The TW parameter can be a useful indicator to verify the pure tone audiometry results and should be used regularly for identifying middle ear problems leading to conductive hearing loss.
Keywords: Conductive hearing loss, middle ear, tympanometric width, tympanometry
|How to cite this article:|
Zakaria MN, Romli M, Mohamad WN, Awang MA, Wahab NA. The diagnostic value of tympanometric width in identifying middle ear disorders. Indian J Otol 2020;26:186-90
|How to cite this URL:|
Zakaria MN, Romli M, Mohamad WN, Awang MA, Wahab NA. The diagnostic value of tympanometric width in identifying middle ear disorders. Indian J Otol [serial online] 2020 [cited 2021 Mar 7];26:186-90. Available from: https://www.indianjotol.org/text.asp?2020/26/3/186/304278
| Introduction|| |
It is evident that hearing loss can occur at all ages. There are generally three types of hearing loss. If there are problems affecting the external ear canal (e.g., wax occlusion, osteoma, exostosis etc.,) tympanic membrane (TM) (e.g., perforated TM) and middle ear (e.g., otitis media with effusion, cholesteatoma, ossicular chain fixation, etc.,) conductive hearing loss (CHL) would occur., On the other hand, if the inner ear and/or neural part of the hearing system is compromised, the affected individuals are said to have sensorineural hearing loss (SNHL). Mixed hearing loss (MHL) is a condition where both CHL and SNHL are present (i.e., all parts of the ears are affected). Depending on the cases, CHL is typically treated with medication and/or surgical approach, while those with SNHL are commonly fitted with hearing amplification devices.
Since specific management approaches are required for different types of hearing losses, proper hearing assessments are, therefore, imperative. In clinical settings, patients with the complaint of hearing loss typically undergo routine audiological tests, including otoscopy, pure tone audiometry (PTA), and tympanometry. In the otoscopic examination, the condition of the ear canal, TM and middle ear are visually inspected. In the PTA testing, the degree of hearing loss (ranging from mild to profound) and the type of hearing loss (CHL, SNHL, or MHL) are determined at specified frequencies. To achieve this, air conduction thresholds (obtained with the use of headphones) and bone conduction thresholds (recorded with a bone vibrator placed on the mastoid area) are measured using a standard threshold seeking technique. The degree of hearing loss is determined based on the air conduction thresholds. The type of hearing loss, on the other hand, is diagnosed based on air-bone gaps., This test, however, is highly subjective and thoroughly dependent on patients' cooperation. Tympanometry, on the other hand, is an objective test to measure the mobility of TM and the middle ear function. For achieving accurate clinical diagnoses, the results of these audiological tests are integrated and concluded.
In the tympanometric testing, a probe (consisting of a miniature speaker, a sensitive microphone, and an air pump) is inserted into the external ear canal and an air-tight seal is created. A low tone (226-Hz frequency) is typically presented by the speaker, and the air pressure is varied (typically from −200 to +400 daPa). The amount of sounds reflected by the TM is measured by the microphone as the air pressure changes. The tympanometric graphical results, known as tympanograms are then produced. It is worth noting that the tympanometric device must be calibrated accordingly to ensure the validity and reliability of its results.
Depending on the middle ear status, there are different types of tympanograms., If the middle ear is healthy, a Type A tympanogram is obtained. When the middle ear is compromised (e.g., otitis media with effusion), a Type B tympanogram is produced. Those patients with Eustachian tube dysfunction typically show a Type C tympanogram. To categorize the different types of tympanograms, three tympanometric parameters are typically used, i.e., static admittance (SA, in ml), tympanometric peak pressure (TPP, in daPa) and ear canal volume (ECV, in ml). The SA parameter specifically measures the compliance of the middle ear system, which is often compromised in cases such as otitis media with effusion, otosclerosis, ossicular chain discontinuity, and others. In this regard, a flat tympanogram (SA value of around 0 ml) is commonly noted in otitis media with effusion cases, while abnormally low and high SA values are observed in otosclerosis and ossicular chain discontinuity cases, respectively., The TPP parameter provides information on the middle ear pressure, that is typically abnormal (i.e., more negative) when the Eustachian tube is blocked in a prolonged manner. The ECV value, on the other hand, is altered in the presence of wax occlusion (i.e., abnormally low ECV) or perforated TM (i.e., abnormally high ECV).,
The normative values for each tympanometric parameter have been established for specific populations.,,,, In this regard, it has been demonstrated that the tympanometric values for individuals from different ethnic groups are statistically different., Moreover, the tympanometric results are also affected by gender.,,, For example, among male Caucasian adults, the ranges of normative values for SA, TPP and ECV are 0.30 ml–1.38 ml, −22 daPa–14.0 daPa, and 0.72 ml–2.06 ml, respectively. Comparatively, among male Asian adults, the corresponding normative data for SA, TPP and ECV are 0.24 ml–0.82 ml,−50.15 daPa to − 3.35 daPa and 0.88 ml–1.93 ml, respectively. On the other hand, the normative data among female Asian adults are 0.22 ml–0.77 ml, −36.25 daPa to −6.00 daPa and 0.81 ml–1.46 ml for SA, TPP, and ECV parameters, respectively. The use of appropriate normative data is, therefore, essential so that middle ear disorders can be diagnosed accurately in clinical settings.
Depending on the chosen cutoff values, the sensitivity (i.e., the ability of a particular test to identify abnormality in pathological subjects) of tympanometry can be as high as 96%. In this respect, the ability of tympanometry to identify the presence of middle ear disorders is sufficiently accurate. Nevertheless, despite having good diagnostic values, a further tympanometric parameter, tympanometric width (TW), is not commonly used in clinical settings. In fact, unlike other tympanometric parameters, TW is not measured automatically in some tympanometric machines. In this paper, we report the usefulness of TW in identifying middle ear disorders leading to CHL.
| Case Report|| |
A 59-year-old Malay lady came to Audiology Clinic, University Hospital with the main complaint of reduced hearing in both ears since several years ago. She was referred from an Otorhinolaryngology (ORL) specialist for full hearing assessments. She felt that her hearing gradually worsened over time. There was no history of otalgia, but she used to have otorrhea involving the right ear (occurred around 2 years ago). She also reported of having pulsatile tinnitus in the right ear (lasted up to 30 min), which could be disturbing to her. She used to work as a hospital nurse and had no loud noise exposure during her working days. No other significant history related to ear, nose, or throat reported. Because of reduced hearing, she faced difficulties to hear conversations and watched television at a high volume. She preferred to use her right ear for the phone conversation for a better understanding. She was generally healthy, and no other significant medical history was reported.
Based on the previous ORL report, her TM looked dull bilaterally. Using a 512-Hz tuning fork, negative Rinne was reported for both ears with a centralized perception in the Weber test. During her visit to Audiology Clinic, the otoscopic examination still revealed dull TM for both ears. She then underwent the tympanometric testing using a 226 Hz tympanometer (GSI TympStar Pro, Grason-Stadler Inc., USA). Based on the established Jerger classification of tympanograms, she was found to have Type A and Type C tympanograms for right and left ears, respectively [Figure 1]. In particular, her right middle ear appeared to function normally. In contrast, the left middle ear pressure was negative (TPP =−192 daPa), implying Eustachian tube dysfunction. The PTA testing was then performed according to the standard clinical protocol using a two-channel audiometer (GSI 61, Grason-Stadler Inc., USA). As such, air conduction thresholds were measured at octave frequencies between 250 Hz and 8000 Hz with TDH-39 headphones. The bone conduction testing was conducted at 250 Hz–4000 Hz frequencies using a B71 bone vibrator. As shown in [Figure 2], she was found to have a mild to moderate CHL in the right ear. In the left ear, a mild-to-severe CHL was observed. Most prominently, large air-bone gaps were noted for both ears, particularly at low frequencies (as large as 50 dB at 250 Hz), implying the presence of notable conductive elements [Figure 2].
Collectively, the presence of large air-bone gaps in PTA was not consistent with the tympanogram types obtained. We then measured the TW manually for each tympanogram (calculated at 50% of the peak height). As revealed in [Figure 1], the TW values were abnormally large, i.e., 325 daPa and 308 daPa for right and left ears, respectively. Based on these values and the tympanogram shapes (rounded peaks), it is highly possible that both ears would have more “serious” conductive problems. To further ascertain the findings, the acoustic reflex testing was performed ipsilaterally and contralaterally at 500 Hz, 1000 Hz, and 2000 Hz frequencies. Sensibly, no measurable acoustic reflex was observed at maximum intensity levels at all frequencies and test conditions. It is worth noting that all audiological tests were performed by an experienced audiologist in a soundproof room. The devices used were all in a good condition and had been calibrated regularly.
| Discussion|| |
Tympanometry is an essential part of routine audiological tests. Due to its objective nature, the status of middle ear function can be conveniently measured. In clinical settings, tympanometric parameters, including SA, TPP, and ECV are commonly used to conclude the tympanogram types and identify the possible middle ear problems. The TW parameter, on the other hand, is not commonly utilized and has to be manually calculated in some tympanometric machines.
In this case report, when the tympanograms were analyzed according to the types, inconsistencies occurred with the PTA results. That is, one would not expect to have such large air-bone gaps when the type of tympanogram was indicative of either normal (Type A) or “nearly” normal middle ear function (Type C). As such, the information gathered from the typical tympanometric parameters was not sufficient to provide insight into the exact middle ear status. Favorably, the inclusion of TW revealed more sensible results (i.e., better consistencies with PTA results) implying the presence of notable CHL in both ears. From a research perspective, TW was reported to have good diagnostic values in detecting middle ear disorders., Depending on the cutoff point, its sensitivity and specificity can be as high as 91% and 90%, respectively. Employing a less stringent criterion (<275 daPa), the sensitivity of TW was 81% sensitivity and its specificity was 82%.
It is worth noting that the “abnormal” TW results of our patients were ascertained by comparing them with the respective normative data obtained from studies involving Asian adults., In a study by Manchaiah et al., SA, TPP, ECV, and TW results were obtained from older Chinese adults (with a normal middle ear function) categorized into three age groups (60–69 years, 70–79 years and ≥80 years). As reported, no significant age effect was found on all tympanometric parameters. The upper limit of TW (90% range) was 109 daPa. In a study by Lih et al., the tympanometric results were compared between healthy Chinese and Malay adults (aged 20–25 years). While comparable SA, TPP, ECV, and TW results were found between the ethnic groups, significant effects of gender were noted on SA and ECV. For the 90% range, the reported upper limit of TW was 110 daPa for females. As indicated in [Figure 1], the TW results of our patient were abnormally higher than the upper limits of the aforementioned normative values (i.e., 325 daPa and 308 daPa for right and left ears, respectively). Nevertheless, tympanometric results can also be affected by the ethnicity factor. For example, the SA, TPP, ECV, and TW results have been found to be significantly different between Caucasian and Chinese adults. In this regard, the tympanometric normative data for specific ethnic groups should be established and used for achieving accurate clinical diagnoses.
In addition, when the tympanogram types and the PTA results were not consistent, conducting the acoustic reflex testing was advantageous. As such, the absence of acoustic reflex at maximum levels would indicate the presence of notable CHL in both ears (supporting the PTA results). In contrast, if the air-bone gaps in PTA were not genuine (suggestive of sensorineural loss), the acoustic reflex would be present with normal or elevated acoustic reflex thresholds. Nevertheless, in cases where the degree of hearing loss exceeds the moderate range, the acoustic reflex is typically absent due to the “tone effect” phenomenon (i.e., due to an ear pathology, the incoming tone is attenuated and not loud enough to stimulate the stapedius muscles). In this regard, the absence of acoustic reflex is because of the insufficient intensity level of tone rather than the presence of CHL. Alternatively, having TW information is beneficial to determine the middle ear condition.
It is also worth pointing out that the PTA findings were, in fact, consistent with the traditional tuning fork test results. In particular, the presence of large air-bone gaps in PTA was in agreement with the negative Rinne result for both ears. Hearing healthcare professionals (especially audiologists) may also want to consider this information in concluding the hearing diagnosis. In fact, it is also beneficial if audiologists are properly equipped with knowledge and skills to perform the tuning fork tests, especially in situations where tympanometry or acoustic reflex test could not be carried out (e.g., due to faulty or uncalibrated devices).
Taken together, it was believed that the middle ear function was significantly compromised in both ears, even though the tympanogram was “normal” (Type A) for the right ear and indicative of a “mild” middle ear problem (Type C tympanogram) for the left ear. The patient was then referred to the ORL doctor for further assessments and management.
| Conclusions|| |
In clinical settings, the information gathered from the typical tympanometric parameters (SA, TPP, and ECV) and tympanogram types can be insufficient to detect middle ear disorders. On the other hand, the TW parameter is a useful indicator to verify the PTA results and should be used regularly for identifying middle ear problems leading to CHL.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given her consent for her images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]