Relationship Between Tympanogram and Middle Ear Disease

There were 3/212 VTGMT cases, all of which were non-dangerous VTGs, occurring mainly in the age group of 36-48 months. This result is similar to the study of Nguyen Van Ninh et al.32with a VTGMT rate of 1.1%. Children are advised to follow up every 6 months, instructed on care, avoid swimming and water in the ear to limit ear discharge. When the child grows up, if there is a significant impact on hearing, the palate and the function of the Eustachian tube are stable, surgery can be performed to patch the ear.

The relationship between middle ear disease and age group is shown in Figure 3.2, in which the rate of OTUD in the age group >12-24 months is highest with 71/98 ears accounting for 72.4%. Atrial fibrillation is most common in the age group >5 years with 14/36 ears accounting for 38.9%. It can be seen that the rate of otitis media has a change in structure according to age group. In the period under 48 months, middle ear disease is mainly acute inflammation or otitis media with effusion, while in the period over 48 months, the rate of atrial fibrillation is found in 21 ears. According to Zingade76(2009) 45% of VTGUD in the 1-2 year old group increased to 80% in the 4-5 year old group. According to Paradise139,, Dang Hoang Son167The incidence of VTGUD varies with age, with the peak age of incidence being 2 years. Teele168(1989) found that the incidence of the disease was highest in 2-year-old children, and tended to decrease after 7 years of age. Kwan169(2011) also found that most cases of VTGUD appeared before 1 year of age. The rate of VTGUD in the first 2 years of life in this study was 76.1%. The change in the structure of middle ear pathology by age group is consistent with the development of children with hearing loss. When children are older than 5 years old, the function of the Eustachian tube is improved, the resistance of children is better, helping to reduce the rate of VTGUD and VTGCT. At the same time, in children with more severe Eustachian tube dysfunction, VTGUD progresses to atrial collapse.

The relationship of KHVM lesions to middle ear disease is determined in Table 3.9, in which the rate of VTGUD in the unilateral and bilateral KHVM groups was 46/62 ears (74.2%) and 92/150 ears (61.3%), respectively. VTGCT occurred with a rate of

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were 9/62 (15.3%) and 20/150 (15.5%), the difference between the groups was not statistically significant with p>0.05. The rate of otitis media in the KHVM type B groups was 57/88 ears (64.8%); type C was 52/72 ears (72.2%) and type D was 29/52 (55.8%). The difference was not statistically significant with p>0.05. Thus, the rate of otitis media did not differ in the KHVM groups as well as the side of the diseased vault. It is possible that the levels of KHVM affect the Eustachian tube function similarly in KHVM patients. This result is consistent with Xing158(1998) studied 43 cases of otitis media and found that otitis media did not differ between the types of clefts. According to Probst148 , eustachian tube dysfunction and palatal muscle abnormalities, combined with other causes of VTUD, did not depend on the type and side of the cleft. With tympanic collapse, the incidence in the bilateral group was 20/150 ears (13.3%), higher than in the unilateral group of 1/150 ears. These are usually large otitis media, found in older children. It is possible that eustachian tube dysfunction, combined with age, leads to prolonged eustachian tube dysfunction, affecting the middle ear in this case.

4.1.3 Assessment of middle ear function through tympanometry

4.1.3.1 Tympanogram morphology

Tympanometry is one of the objective measurement methods, valuable in assessing middle ear lesions that we cannot see directly. Tympanometry helps us indirectly assess the function of the Eustachian tube, the activity of the tympanic membrane system and fluid in the tympanic cavity.

Tympanometry was performed on 209/212 ears with intact tympanic membranes. According to Figure 3.3, type B tympanograms appeared in 161/209 ears (77.0%) and type C tympanograms appeared in 25/209 ears (12.0%). There were 12/209 (5.7%) type As tympanograms. This result is similar to the study of Zingade76(2009) had 64.77% B-type tympanograms, and Khan77(2006) B-type tympanogram accounts for 75%. According to author Luong Hong Chau6Tympanogram is a common finding in VTUD. Tympanogram is the result

The results are objective and very valuable in VTGUD, but it also depends on many factors, so there are still errors when diagnosing based only on the tympanogram. According to the author Grant170(1988) the accuracy of tympanometry in VTGUD is 90%, while microscopy is 95.7%, tympanic membrane puncture is 97.4%, the author's study showed 92.2% of type B when evaluated through tympanic membrane puncture with fluid accounting for 46/51 cases. According to Kemaloglu171(2000), to confirm the diagnosis of VTGUD, tympanometry has a sensitivity and specificity of 96% and 92%, respectively.

According to Pichichero172, using a tympanometer provides quantitative information on the function and presence of fluid in the middle ear. It is possible to combine the use of an otoscope with a squeeze bulb before tympanometry. This helps improve accuracy because many abnormalities in the tympanic membrane and ear canal affect the tympanometry results. After otoscopy, determining the presence of earwax in the ear canal, tympanic membrane perforation or tympanic membrane ventilation tube, and the characteristics of the tympanic membrane in terms of color, mobility, location and transparency help to obtain more accurate results from tympanometry173. When using only one method, otoscopy with an air bulb has better sensitivity and specificity than tympanometry for diagnosing VTGUD174. Both methods can complement each other because otoscopy with a bulb provides a qualitative measurement of the mobility of the tympanic membrane, while tympanometry provides quantitative information on the mobility of the ossicular tympanic membrane system175 .

Author Nguyen Tan Phong53(2000) proposed a classification based on the morphology of tympanogram changes. According to this classification, diaphragmatic tympanogram was found in 186/209 ears, accounting for 89.0%, and vertical tympanogram was found in 12/209 ears, accounting for 5.7%. Combined lesions of tympanogram changes were found in 198/209 tympanograms, accounting for 94.7%. Tympanogram changes in the form of complete tubal obstruction and tertiary changes were both found in 161/209 ears, accounting for 77.0%. The results were higher than those of Chau Chieu Hoa48with obtuse apex, low apex, negative deviation and flat tympanogram morphology is 58.0% and obtuse apex, negative deviation tympanogram is 42.0%. The division according to tympanogram fluctuation morphology helps to refer to determine the cause.

Causes and changes over time of middle ear disease.

4.1.3.2 Relationship between tympanogram and middle ear pathology

Through Chart 3.4, type B tympanogram was found in 124/138 (89.9%) of VTGUD group; VTGCT was 24/29 (82.8%) and atrial collapse was 13/21 (61.9%). The difference in tympanogram types in VTG groups was statistically significant with p<0.05. It can be seen that type B tympanogram was found at a high rate in both VTGUD, VTGCT and atrial collapse. This result is consistent with Moller's study25with middle ear pressure often reduced by more than -150 mmH2O, tympanogram type B is found in 85% of cases. This shows that the main cause of ear pathology in KHVM patients is due to Eustachian tube dysfunction. Abnormalities in the attachment points of the levator palpebrae and tensor palpebrae muscles, and obstruction of the tube increase negative pressure in the tympanic cavity, hindering the mobility of the ossicular tympanic membrane system caused by pressure. In 2003, author Luong Hong Chau6found that a flattened tympanogram with compliance around zero and a low pressure index below 150 was a cross-sectional feature of late-stage otitis media with effusion and tympanic membrane collapse, accounting for 77.9% of non-perforated tympanic membrane rupture. Compliance is the most meaningful index for diagnosis and monitoring of the disease.

According to Table 3.11, tympanogram type B is most common in glue ear infection with 92/96 ears (95.8%). The difference is statistically significant with p<0.05. It can be seen that the nature of middle ear fluid affects the impedance of the tympanic membrane ossicle system. Therefore, tympanogram morphology plays an important role in helping to diagnose and predict the types of VTGUD.

Type C tympanogram is most common in the group of atrial collapse with 6/21 tympanograms accounting for 28.6%. According to Khieu Huu Thanh176 , the most common tympanograms in atrial collapse are types B and C with a ratio of 30/66 and 26/66, with manifestations of dysfunction of the Eustachian tube and the tympanic membrane ossicles in the group of atrial collapse with poor mobility. There is a difference because in the study, the degree of atrial collapse is mainly grade II and III. Cases of grade IV atrial collapse are consulted and continued to be monitored.

Periodically, surgical treatment of the middle ear after performing a stable palateplasty. This is consistent with the results in Table 3.11, the C-shaped tympanogram is found in grade II tympanic collapse in 4/10 ears (40%).

Eustachian tube obstruction is also evident in normal ears, with no fluid in the tympanic membrane and no signs of collapse. The rate of C-shaped tympanograms in normal ears is quite high, up to 28.6%. The tympanic membrane in these cases is often concave and loses its shine.

Tympanograms with As type were found in 2/21 ears with atelectasis (9.5%) and 4/21 normal ears (19.0%). These were all ears with quite large calcifications in the anterior angle and around the handle of the malleus. It is possible that the stiffness of the tympanic membrane system increased, causing the peak of the tympanogram to be lowered below 0.5ml.

4.1.4 Assessment of middle ear function through hearing

4.1.4.1 Audiogram morphology

In the study, hearing was assessed by threshold audiometry. There were 24 patients who had their audiometry performed, with 48 ears. The youngest age measured was 52 months. There were 82 patients who did not have their audiometry measured, mainly in the age group of 12-48 months. At this age, children have difficulty cooperating for audiometry. In addition, some children in the study were ethnic minorities, communicating in Vietnamese completely indirectly through their families. This is a limitation of the study, which was overcome by using age-appropriate measurement techniques. In older children, they can cooperate, and when measured, they will respond to audible signals by pressing a button or raising their hands. For young children, conditioned play audiometry (CPA) was used, with the same principle as threshold audiometry, building a conditioned reflex by playing an acoustic signal as a condition of the game. The researchers were doctors and nurses with experience in audiometry at the Vietnam Cuba Hospital, trained before the study.

There were 37/48 audiograms (77.1%) with conductive hearing loss, of which mild conductive hearing loss accounted for 20/48 ears (41.7%). There were 2 audiograms with mild sensorineural hearing loss, 6 audiograms with mixed hearing loss. This result is similar to the study of Flynn et al. 177 with a rate of 83.1% conductive hearing loss. Mild hearing loss was present in 24/48 ears, accounting for 50.0%. The average PTA was 28.1  9.2 dB. This reduction is similar to the results of Bluestone and Klein 163 and many other authors also had results of 25-30 dB178,179. Author Paradise 22 (1969) stated that hearing in children with hearing loss tends to improve, not decline with age. According to author Sheahan 37 (2003), the average hearing loss is 32 dB. This hearing loss is lower than the study of Mai Y Tho 47 on children with otitis media with effusion. This difference may be due to the fact that the subjects of Mai Y Tho's study were children with otitis media with otitis media indicated for OTK placement and treated at the Central Ear, Nose and Throat Hospital, so the level of hearing loss is more severe. According to Bluestone 163, hearing loss greatly affects the child's ability to communicate, develop and integrate into life. Therefore, patients with hearing loss need to be monitored and treated promptly.

In addition to pure tone audiometry, in young children, hearing can be assessed by objective audiometric methods such as OAE, ABR or ASSR. However, these methods have certain disadvantages. OAE measurement only allows qualitative determination of hearing without indicating the type of hearing loss in children. According to Thakur180 , OAE can detect ears with normal hearing, but cannot assess the difference between the VTGUD, sensorineural hearing loss and VTGMT groups. With ABR and ASSR, although there have been studies showing that they are more effective in determining the level of hearing loss in children with VTGUD, the need to put the child to sleep during the measurement is a major difficulty when performing with children with KHVM. ASSR also has less sensitivity to the lower hearing threshold.

30dB is a common threshold in children with hearing loss.181Therefore, OAE, ABR and ASSR measurements were not performed in this study.

4.1.4.2 Relationship between audiogram and middle ear disease

According to Table 3.13, conductive hearing loss was found in 24/28 ears (85.7%), the average PTA in the VDU group was 29.6±8.5 dB, higher than the normal group by 15.6±3.1 dB, the average ABG in the VDU group was 19.4±7.0 dB compared to the normal group by 9.0±4.6 dB. The difference was statistically significant with p<0.05. This result is consistent with studies showing that VTGUD causes conductive hearing loss, reducing hearing from 0-50 dB in the communication frequency range (500Hz-2000Hz), averaging about 25-30 dB, of which about 20% lose hearing over 35 dB at low frequencies. 13,182 The mechanism of hearing loss for low-frequency sounds is due to fluid retention reducing the conduction range and changing the position of the air space in the middle ear, reducing hearing for high-frequency sounds is due to an increase in the volume of the tympanic membrane carried by fluid in the middle ear. 183 In addition, fluid along with reduced tympanic cavity pressure also limits the movement of the ossicular chain. The above reasons increase the acoustic impedance of the middle ear, reducing the child's hearing. 182 Regarding the relationship between fluid characteristics and hearing loss level, through Table 3.14, the PTA index in the groups of serous otitis media, glue otitis media and purulent otitis media is not statistically different with 0>0.05.

There was 1 case of sensorineural hearing loss in VTGUD with a rate of 3.6% and 3 cases of mixed hearing loss with a rate of 10.7%. Some studies show that recurrent, prolonged otitis media with effusion can also cause sensorineural hearing loss at high frequencies above 4000 Hz.184According to Mutlu185 , there are two mechanisms that cause bone conduction damage in VTGUD causing sensorineural or mixed hearing loss. The first is due to temporary inhibition of the antiphase vibration of the round window and oval window caused by middle ear pressure or reversible cochlear dysfunction.

by changes in the composition of the ionic fluids of the inner ear, leading to a decrease in the hearing threshold around 2000Hz. The second mechanism is a true disorder of inner ear function that does not recover after an episode of VTGUD.186In the study of Aithal et al.187 , the mean bone conduction hearing threshold at 2000Hz was 11.6dB.

In the group with atrial collapse, the most common type of conductive hearing loss was found in 12/16 ears, a rate of 75.0%. There was 1/16 (3.6%) ear with receptive hearing loss and 3/16 ears (10.7%) with mixed hearing loss. This result is also consistent with the study of Nguyen Thi Minh Tam102on closed tympanic membrane disease, in which tympanic membrane collapse accounted for 30%, 20/33 cases were conductive hearing loss. The hearing loss level in the tympanic membrane collapse group was mainly very mild and mild with a ratio of 7/16 ears (43.8%) and 2 cases of moderate hearing loss were both found in grade III tympanic membrane collapse. The average PTA of the tympanic membrane collapse group was 28.7±9.3 dB, a statistically significant difference from the normal ear group of 15.6±3.1 dB. Comparing between the levels of tympanic membrane collapse, the difference in PTA was not statistically significant with p>0.05. This result is also consistent with author Hoang Vu Giang83The audiogram shows that the collapsed tympanic membrane is a conductive hearing loss, increasing from grade I to grade IV in the range of 20-49 dB, while the localized collapsed tympanic membrane is a mixed conductive hearing loss. According to Khieu Huu Thanh et al.176 , the XNTB grade II and III have ABGs in the range of 24.3±9.6 dB and 24.5±10.98 dB.

In normal ears, 1/4 of the ears have mild conductive hearing loss. The diagnosis of normal ears is based on the image of the ear without fluid, no phenomenon of tympanic membrane retraction or collapse. However, in this ear, there is a small piece of calcification, accompanied by the phenomenon of partial obstruction of the Eustachian tube, diagnosed by tympanogram C. This may be the cause of the patient's hearing loss.

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