|Year : 2013 | Volume
| Issue : 2 | Page : 61-66
Cephalometric assessment of Eustachian tube parameters in Down syndrome and chronic otitis media
Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai, India
|Date of Web Publication||21-Oct-2013|
Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai - 400 008
Source of Support: None, Conflict of Interest: None
Aim: In this study, cephalometric assessment of Eustachian tube parameters (linear and angular) in Down syndrome (DS) and chronic otitis media (COM), and their comparison with those of normal group were done. In DS, COM, and normal groups, the Eustachian tube length (ET length), total cranial base (TCB), posterior upper facial height (PUFH), maxillary depth (MD), sella-basion (s-ba) to palatal line (s-ba to PL), and s-ba to ET length were evaluated. Materials and Methods: The study comprised 75 subjects of both sexes in the age range of 7-20 years. Digital lateral cephalometry was performed for DS (n = 25), COM (n = 25), and controls (n = 25). Results: In the present study, the ET length, TCB, PUFH, and MD were found to be significantly reduced in the DS as compared to the COM and normal groups. s-ba to PL and s-ba to ET were significantly reduced. Conclusion: Craniofacial malformations and associated disability of DS warrants further research. Aberration in the dimension of the region of the ET can be considered as a predisposing factor for COM in DS. Assessment of ET-related parameters in COM and DS is essential in gauging the functional disability and planning measures to treat the same.
Keywords: Cephalometry, Down syndrome, Eustachian tube, otitis media
|How to cite this article:|
Khanna S. Cephalometric assessment of Eustachian tube parameters in Down syndrome and chronic otitis media. J Oral Maxillofac Radiol 2013;1:61-6
|How to cite this URL:|
Khanna S. Cephalometric assessment of Eustachian tube parameters in Down syndrome and chronic otitis media. J Oral Maxillofac Radiol [serial online] 2013 [cited 2019 Jun 17];1:61-6. Available from: http://www.joomr.org/text.asp?2013/1/2/61/120117
| Introduction|| |
Multidisciplinary management requires a good knowledge of associated disorders related to Down syndrome (DS), which would be beneficial for clinicians and basic researchers.
Between 38% and 78% of children with DS have conductive hearing loss and 90% of these are caused by chronic otitis media (COM) with effusion.  Anatomical and functional insufficiency of the Eustachian tube More Details (ET) is an important factor in the pathogenesis of COM and is linked to its postnatal growth and development. ,
In a stepwise correlation regression analysis, the cephalometric measurements predictive of the evolution of the ET were found to be the length of the ET, total cranial base, posterior upper facial height (PUFH), maxillary depth, angle s-ba-PL and angle s-ba-ET length. Also, the dimensions of total cranial base (TCB), PUFH, and maxillary depth (MD) illustrated the length of the ET. 
Craniofacial development was analyzed in 1896 patients with DS (age 0-14 years) in comparison to a matching control group consisting of 1154 healthy children. These findings indicated that craniofacial dysplasia is already present at birth, becoming more severe with increasing age. Patients with DS who are in a period of growth demonstrate reduction of the anterior skull base. 
Cephalometric radiography is an extensively used technique for making standardized head measurements in orthodontics and growth studies.  Lateral cephalometric radiography not only provides for research on living subjects; but has also been used for otologic research and measurement of length and position of ET, employing skull base landmarks. ,,,,,,
The management of craniofacial anomalies has so far escaped the rigors of contemporary health technology assessment, causing great confusion around what constitutes optimal management. Therefore, craniofacial malformations in DS warrant further research.
The aim of this study was craniofacial radiological assessment of ET parameters (linear and angular) in DS, COM, and comparison with normal group.
The craniofacial landmarks included were the following [Table 1], [Figure 1]:
- Linear measurements
- ET length (mep-pt)
- TCB [nasion (n)-basion (ba)]
- PUFH [sella (s)-posterior nasal spine (pns)]
- MD [(anterior nasal spine (ans)-(pns)]
- Angular measurements
- s-ba to palatal line (PL)
- s-ba to ET length
| Materials and Methods|| |
The study comprised DS, COM, and normal groups, and 25 subjects of both sexes in the age range of 7-20 years were included in each group (n = 25). Approval was obtained from the institutional ethics committee. Digital lateral cephalometry was performed for all the subjects in an identical manner. , They were briefly exposed in erect position. Teeth were occluded, lips were in repose, and head was stabilized with a cephalostat. Tracings were done for the cephalograms and linear and angular measurements were recorded. Before inclusion of participants in the study, informed written consent was obtained in local language from them. Over testing was avoided and appointments for testing were given as per subjects' convenience. Patients of DS with determined genotype and no other disability were included in the study.
The data were subjected to statistical analysis using both Microsoft Office Excel (Microsoft Corporation, Redmond, WA, USA) and Statistical Package for Social Sciences (SPSS) software. The chosen confidence level was 95%. Univariate statistical methods were used to calculate descriptive statistical parameters (mean, median, and standard deviation) for each parameter in the three groups. Tukey's test and Kruskal Wallis one-way analysis of variance (for results with a non-normal distribution) were applied for analysis.
| Results|| |
The mean linear measurement of ET length (mep-pt) was decreased in both DS and COM groups as compared to the normal group (P < 0.001 or 2.45E-05) [Table 2], [Figure 2].
The mean linear measurement of TCB (n-ba) in DS group was decreased as compared to COM and normal groups, which was statistically significant (P < 0.001) [Table 2], [Figure 2].
The mean linear measurement of PUFH (s-pns) was decreased in the DS and COM groups as compared to the normal group, which was statistically significant (P < 0.001 or p. 2.37E-07). The decrease was stark in the DS group [Table 2], [Figure 2].
The mean MD (ans-pns) in DS and COM groups was markedly decreased as compared to the normal group. The decrease was more in the DS group and was statistically significant (P < 0.001 or p. 1.01E-06) [Table 2], [Figure 3].
|Figure 3: Comparison of MD (ANS-PNS), S-Ba to PL and S-Ba to ET length among study groups|
Click here to view
Mean angle s-ba to PL was decreased in the DS and COM groups as compared to the normal group and the decrease was more in DS which was statistically significant (p. 3.44E-10) [Table 2], [Figure 3].
Mean angle s-ba to ET length was significantly decreased in the DS and COM groups as compared to the normal group and the decrease was more marked in the DS group (P < 0.001 or p. 2.35E-05) [Table 2], [Figure 3].
| Discussion|| |
DS is the most commonly occurring genetic abnormality, involving 1 in 700 births.  The increasing life expectancy of individuals with DS has revealed the presence of several unexpected pathological processes. The cause of DS is one of the three types of abnormal cell division involving chromosome 21. All three abnormalities result in extra genetic material from chromosome 21, which is responsible for the characteristic features and developmental problems of DS. Among these, the Ear, Nose, and Throat (ENT) disorders hold an important place because of their high incidence and severity. Accurate knowledge of the pathophysiology underlying oral facial disorders provided an understanding of the reasons for the development of the upper airway obstruction, obstructive sleep apnea syndrome, deafness, speech delay, and otitis media that occur frequently in these children.  Growth and development of the anatomic region of ET is associated with parameters related to other parts of the craniofacial skeleton. In adults, ET runs downward, forward, and medially from the middle ear, and has two elements, a lateral bony portion arising from the anterior wall of the tympanic cavity and a medial fibrocartilaginous part entering the nasopharynx.  ET performs clearance (drainage) of secretion produced within the middle ear into the nasopharynx. Impairment of the latter can lead to frequent otitis media. 
The extent of the ET is from the tympanic portion of the temporal bone (TB) to the pterygoid plates (PP) of the sphenoid bone (SB) through the sphenoid sulcus at the junction of the petrous portion of the TB and SB. , Previous research states that the ET and muscles (tensor veli palatini and levator veli palatini) are associated in anatomical and functional aspects and are located in the same anatomical space. , Review of literature reveals that ET and its muscles continue to develop till adulthood during which the lumen of ET increases and gets inclined laterally and superiorly. ,,,, The landmarks of ET length (mep and pt) were not the actual anatomic points if compared with the skull measurements performed in previous studies. ,, The "pt" point considered was a point between posterior border of the maxilla and anterior border of the PP and served as an indicator of nasopharyngeal end of ET. Therefore, this point was not located on the medial PP which is the true localization of nasopharyngeal end of ET.
Data analysis of this study shows that craniofacial malformations have a deterministic effect on the dimension of the region where ET is located (ET length).
In the present study, the ET length was found to be significantly reduced in the DS group as compared to the COM group and normal group. TCB was reduced in the DS group as compared to the COM and normal groups, which was significant. PUFH was reduced in DS and COM groups significantly as compared to the normal group. MD was reduced in COM group and further in DS group, which was significant. s-ba to PL was significantly reduced in the DS and COM groups, but the decrease was more in DS group. s-ba to ET was reduced in COM and DS groups, which was found to be statistically significant. As sella, ans and ba are considered constant points through life, the s-ba reference for angular parameters was appropriate. Angulation of the ET length to this reference would help gauge the superior-inferior relation of the area where ET is located.
As audiological parameters were not considered here, it was not possible to attribute the risk of otitis media to a particular craniofacial parameter. However, previous studies state that ET length abnormalities increase the risk of otitis media. ,,, Lateral cephalograms provide bilateral data and measurements are the mean of the left and right sides of the skulls.  Previous data indicate that there was high correlation of measurements of cranial base and ET between the left and right halves of the skull. , Otitis media is a bilateral disease, and using the mean data of the left and right sides to correlate with midline parameters of the craniofacial skeleton is, therefore, justified.
Otitis media is most common during childhood when tubal dysfunction is more prevalent; its incidence decreases with maturity. This decrease has been correlated with the shift in the position of the tube, which is more vertical in adults. This change can be attributed to the growth of the cranial base, nasomaxillary complex, and mandible, which are the major developing units of the craniofacial skeleton.  The region of the ET is between the maxilla and posterior cranial base (PCB). ,,
The development of the brain leads to the anterior movement of the middle cranial fossa along with nasomaxillary complex and PP. Bone remodeling and primary displacement of the posterior maxilla lead to downward and forward movement of the nasomaxillary complex.  The expansion of the posterior maxilla, PUFH, and MD are considered to be the main explanatory variables of the region of ET. ,,
Previous research suggests that the genesis of otitis media could be linked to poor ET function. It is established that brachycephalic adults were more likely to have relatively straight tubes which are associated with otitis media. , Cranial base dimensions, MD, and PUFH are linked to otitis media. ,,,,,,, ET dimensions reach adult length by 7 years.  In adults, the tube is approximately 45° related to the horizontal plane. ET length, PUFH, and MD are shorter in DS and children with secretory otitis media, so it is more likely that secretions reflux into the middle ear. ,,,, It is also established that the length of PCB is shorter in cleft palate and in children with otitis media with effusion.  Histopathologic studies also reveal that ET length in dysfunction specimens is shorter than in age-matched controls, which might explain tubal dysfunction. 
Increased incidence of otitis media is linked to aberrations in the dimensions of the ET region and dysfunctional ET. ,,, It has also been reported that developmental structure of the supratubal recess and its pneumatization is associated with growth of the bony ET and precedes the formation of air cells in the mastoid process. 
| Conclusion|| |
The results indicate that the alterations in the dimensions of the region where the ET is located predispose to COM in DS. Moreover, it can be hypothesized that aberration or cessation in growth of parts of the craniofacial skeleton leads to imbalances in the ET which predispose to otitis media. The study aims to bridge the research gap between craniofacial malformations of DS and their association with otitis media. A coordinated approach aimed at the holistic management of the pathogenesis of craniofacial malformations may hold the answer to vital questions concerning disability. Further research is required on a larger sample size to fully understand the association between the position of ET and development of COM in children with DS.
| Acknowledgment|| |
Prof. Rangasayee, Former Director, Ali Yavar Jung National Institute of Hearing Handicapped, Mumbai is gratefully acknowledged.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]