SD-DS. 34 INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME 2003: vol. 7, núm. 3, pp

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1 34 INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME 2003: vol. 7, núm. 3, pp Original Relationship between the size of the ear canal and Eustachian tube function in Down syndrome Joan Domènech 1-2, Marta Carulla 2 1 Fundació Catalana Síndrome de Down 2 Facultad de Medicina, Universidad de Barcelona Correspondence to: Dr. J. Domènech Centre Mèdic Down C/ Comte Borrell, 201, ent Barcelona, Spain Artícle received: 30/10/03 Abstract A small outer ear, including the pinna and the ear canal, is one of the hallmarks of Down syndrome (DS). Eustachian tube dysfunction is also a frequent occurrence. A retrospective study was carried out to ascertain the possible relationship between the occurrence of external auditory canal stenosis and the malfunction of the Eustachian tube. Six hundred and twenty-four subjects with DS seen at the Fundació Catalana Síndrome de Down (FCSD), with ages ranging from 8 months to 17 years, were considered. External ear canal diameter was measured and sorted into four categories. Eustachian tube function was assessed with tympanometry. Statistically significant correlations were found between ear canal width and abnormal tympanogram findings, both for the entire group and for the under-5 sub-group, where the correlation was strongest. We may conclude that children and adolescents with DS and with substantial stenosis of the external auditory canal show an increased risk of suffering Eustachian tube dysfunction, more so in the younger group (5 years old and under). This finding should lead to stronger prevention efforts for these subjects. Keywords: Auditory canal. Ear. Down syndrome. Eustachian tube. Tympanometry. Introduction A small outer ear is one of the hallmarks of Down syndrome (DS). The vertical length of the pinna is the most telling measurement, compared to individuals without DS; it is usually two standard deviations below average (1). Mean ear length in newborns with DS is 3.0 cm, compared to 3.6 cm for newborns without DS. Aase et al (2) suggested the need to screen any newborn with ear length shorter than 3.4 cm for DS. The external auditory canal is significantly smaller, too, although its size has not yet been quantified precisely. The difference appears to be greater in children under three, and may be caused by immature bone growth, though the mechanism has not yet been pinpointed. The eardrum is usually normal in shape, size, and

2 2003: vol. 7, núm. 3, pp INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME 35 function. Stenosis of the external auditory canal may cause specific problems. In many children under 3 or 4, a good view of the eardrum can be hard to obtain, so ear conditions are hard to confirm or rule out. A narrow canal can easily be occluded by a small amount of cerumen that would be harmless in a larger ear; moderate hearing loss may even result in such cases (3). The eardrum itself is practically normal, so the canal is hourglass-shaped; if earwax enters the inner third, usually as a result of excessive probing, it may become extremely difficult to remove. Some authors recommend surgery to expand the auditory canals if stenosis persists beyond the age of three, though this seems needlessly aggressive. The Eustachian tube, a key element for correct middle ear functioning, is also different in DS. Functional impairment often occurs, especially in the winter season and in young children. As a result, fluid is retained within the tympanic cavity, the eardrum loses mobility, and hearing loss ensues, either temporarily if the problem resolves or permanently. The high incidence of tubal dysfunction is thought to originate in a degree of hypotonia of the peristaphyline muscles, which open up the tubes when they contract; the etiology of this hypotonia is uncertain. A cleft palate may render the problem more severe, as the levator veli palatini muscles insert into their contralateral counterparts, which is impossible unless the soft palate is whole. A possible relationship had been suggested (4) between external auditory canal stenosis and hypofunctioning Eustachian tubes, but nothing so far had been proved or even quantified. A retrospective study was therefore undertaken to ascertain whether any such relationship exists and, if so, to identify its parameters. Patients and methods Children and teenagers with DS were included in this study. The FCSD database was employed and sufficient data was obtained to include 624 subjects in the study, 326 male and 298 female, aged 8 months to 17 years. There were 84 subjects aged 5 or under at the time the study was undertaken. The size of the external auditory canal was assessed using different-diameter speculi and patients were sorted into four categories (normal, mild stenosis, moderate stenosis, or severe stenosis) according to age-relative size. When stenosis is severe, otoscopy can be difficult to perform correctly, as only a small part of the tympanic membrane is visible, at best. Tube function was assessed using tympanometry. Five categories were established: normal (good eardrum mobility), reduced mobility (mild tubal dysfunction), secretion (significant tubal dysfunction), rigidity (reduced eardrum mobility not directly linked to tubal function), and unreliable (inconsistent data or no obtainable data). Chi-square ( 2 ) tests were employed to correlate auditory canal size and overall normal/non-normal tympanometry results; the tests were also run for two separate age groups (5 and under, and over). Stenosis was subsequently tested for correlation with degree of tubal hypofunction as assessed by tympanometry; again, testing was done separately for the group as a whole and the two age categories listed above. Correlations were considered significant with p = Last of all, the study looked for a statistically significant relationship between the size of the ear canal and the presence of rhinorrhea, nasal obstruction, or acute otitis media.

3 36 INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME 2003: vol. 7, núm. 3, pp Results Table 1 gives external auditory canal size statistics for the group as a whole and for the 5-and-under sub-group. Table 2 shows the tympanometry statistics for the whole group and for the 5-and-unders. Results are expressed as absolute numbers and percentages. A graphic is also included for easier reading. Figure 1 compares external auditory canal stenosis in all children («Global») and in the 5-and-unders, in percentage terms. Figure 2 compares tympanometry results. Significant correlations were found between external auditory canal diameter (normal vs. stenosis) and tympanogram results (normal vs. below normal) for the group as a whole and for those aged 5 and under. A statistically significant correlation was also found between severe stenosis and abnormal tympanogram results in the younger age group, though no such link was found with other degrees of stenosis. No statistical correlation emerged between stenosis and tympanogram results in subjects aged over. Neither was any link found in any age group between auditory canal size and rhinorrhea, nasal obstruction, or acute otitis media. Discussion The findings of this study demonstrate a statistically significant relationship between stenosis of the external auditory canal and Table 1. Degree of stenosis, external auditory canal 5 years or less % 21-25% Mild stenosis % % Moderate stenosis % % Major stenosis % % Table 2. Tympanometry results 5 years or less % % Reduced mob % % Secretion % % Immobility % % Unreliable % % Eustachian tube dysfunction in children and teenagers with DS. Confirmation that subjects with narrower ear canals have a higher incidence of Eustachian tube dysfunction may help towards prevention and may also be of use in encouraging more aggressive or longerterm treatments in such cases, to prevent further complications. Researchers disagree as to the need for early surgery to treat otitis serosa with paracentesis of the tympanic membrane and insertion of ventilation tubes when medical treatment with nasal decongestants, antihistamines, and low-dose steroids fails to solve the problem after a reasonable amount of time. Iino et al. (5), having found more postsurgical complications in children with DS than in their control group, feel that it is best Moderate 28.2% Significant 13% 29% Mild 29.8% Moderate 5 and under Significant 16.7% 25% Figure 1: Degree of stenosis of the external auditory canal in percentage terms, overall and for the 5-and-under group. Secretion Reduced mob. Immobility 10.1% 23,4% Unreliable 21% 31,7% Figure 2: Tympanometry results in percentage terms, overall and for the 5-and-under group. 31% Secretion 19,1% Reduced mob. 5 and under Immobility 5.9% 22.6% 27.3% Mild Unreliable 28.2% 26.2%

4 2003: vol. 7, núm. 3, pp INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME 37 to wait for the condition to resolve and only opt for surgery when it is evidently permanent. Other studies (6), however, detected no higher incidence of post-surgical complications. While such considerations lie beyond the scope of the present article, it is our opinion that the additional anatomical difficulties posed by the narrow external ear canal and retracted tympanic membrane in children with DS should lead to a serious case-by-case consideration of surgical treatment and its individually variable potential complications in relation to realistic improvement chances. Table 1 and Figure 1 show that the overall incidence of external auditory canal stenosis is 70.2%, whereas it is 75% for children aged 5 and under; this appears to show that the problem tends to diminish with growth. Similarly, the rate of mild stenosis is higher for the group as a whole than for the younger sub-group, while moderate to severe stenosis is more frequent in the latter. Interestingly, researchers appear to take very little notice of auditory canal width in children with DS; a search through the literature found no specific study of this matter. The present study only looked at canal width as a potential prognostic factor of Eustachian tube conditions, but it is clearly of some interest and merits specific studies of both incidence, width measurements, and how they relate to growth. Table 2 and Figure 2 show a significant tendency for tympanometry results to be better in the group as a whole than in the younger sub-group. This confirms the impression that Eustachian tube dysfunctions improve with age in these children, as in the general population. Other aspects of the tympanometry findings are also of interest. Only 31.7% of tests were normal, dropping to 26.2% in the younger group - a percentage similar to those found in other studies (4,7). Unreliable results were obtained in 21% and 26.2% of cases, respectively still a higher rate in the younger group. Unreliable results» include failure to achieve a tight seal between the canal and the probe tip, which is essential to the test; several peaks rather than a single one in the tympanogram; or the impossibility of testing due to excessive head movements (a few seconds of immobility are required). The relatively high incidence of unreliable results compared to the general population may be linked to the stenosis itself, which makes this test considerably more difficult to perform, and to the difficulty of immobilizing the child in some cases. Finally, we note an overall 10.1% incidence of eardrum immobility, which does not necessarily entail Eustachian tube dysfunction but may be linked to tympanic cavity malformations or ossicular adhesions. The incidence of ossicular chain malformations is probably much higher in people with DS than among the general population, as otoscopy often shows that the handle of the malleus is curved towards the back; This small abnormality may be linked to other ossicular malformations which may be insignificant in morphological terms but significant in terms of reduced sound transmission down the ossicular chain. This, too, should be the object of specific research. Similarly, an interesting point to note is the lower rate of immobile eardrums (only 5.9%) in the younger group. This finding may be attributed to a gradual development of tympanic adhesions, or ossicular fixation, over time during growth, so that frequency increases with the age of the child. Although Eustachian tube dysfunctions occur more often in children with chronic upper airway problems, no link was found in the present study between a narrow canal and rhinorrhea or nasal obstruction events. Also, there is no apparent link with acute otitis media, frequently associated with Eustachian tube dysfunction. While children with DS are often thought to have a higher-than-average rate of otitis media, our experience does not

5 38 INTERNATIONAL MEDICAL JOURNAL ON DOWN SYNDROME 2003: vol. 7, núm. 3, pp lend support to this theory. It is our impression that, while there may be more episodes of Eustachian tube disorders with mucous secretions in the middle ear, this does not entail a higher rate of ear infections. In conclusion, children and teenagers with Down syndrome and significant stenosis of the external auditory canal, particularly those under five, are at a higher risk for diminished patency of the Eustachian tube. Preventive measures should therefore be particularly stringent for this population in months with higher incidence rates of upper airway inflammation. References 1. Thelander HE, Pryor HB. Abnormal patterns of growth and development in mongolism. An anthropometric study. Clin Pediatr 1966; 5: Aase JM, Wilson AC, Smith DW. Small ears in Down s syndrome: a helpful diagnostic aid. J Pediatr 1973; 82: Pappas DG, Flexer C, Shackleford L. Otological and habilitative management of children with Down s syndrome. Laryngoscope 1994; 104: Schwartz DM, Schwartz RH. Acoustic impedance and otoscopic findings in young children with Down s syndrome. Arch Otolaryngol 1978; 104: Iino Y, Imamura Y, Harigai S, Tanaka Y. Efficacy of tympanostomy tube insertion for otitis media with effusion in children with Down syndrome. Int J Pediatr Otorhinolaryngol 1999; 49: Strome M. Down s syndrome: a modern otorhinolaryngological perspective. Laryngoscope 1981; 91: Maurizi M, Ottaviani F, Paludetti G, Lungarotti S. Audiological findings in Down s syndrome. Int J Pediatr Otorhinolaryngol 1985; 9: