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 Table of Contents  
CASE REPORT
Year : 2018  |  Volume : 24  |  Issue : 2  |  Page : 117-119

Double-Peak tympanometry in keratosis obturans


Department of Otorhinolaryngology, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia

Date of Web Publication4-Sep-2018

Correspondence Address:
Dr. Mohd Khairi Md Daud
Department of Otorhinolaryngology, School of Medical Sciences, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan
Malaysia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_97_17

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  Abstract 


Tympanometry is an effective objective tool used to identify problems in the middle ear. Keratosis obturans (KO) is a rare condition but may cause bony erosion and gradual expansion of the bony external auditory canal (EAC). We report a case of 32-year-old woman with KO who presented with bilateral hearing loss for a few years and right ear pain and discharge for 3 months before visit to an otorhinolaryngology clinic. She was treated by ear drops antibiotic and repeated ear toilet. Tympanometry done revealed a large EAC volume with a double-peak admittance. Double-peak tympanometry with an intact tympanic membrane may indicate diseases causing severe erosion in the EAC.

Keywords: Acoustic impedance test, external ear canal, keratin


How to cite this article:
Aziz A, Daud MK. Double-Peak tympanometry in keratosis obturans. Indian J Otol 2018;24:117-9

How to cite this URL:
Aziz A, Daud MK. Double-Peak tympanometry in keratosis obturans. Indian J Otol [serial online] 2018 [cited 2018 Dec 13];24:117-9. Available from: http://www.indianjotol.org/text.asp?2018/24/2/117/240573




  Introduction Top


Keratosis obturans (KO) is an uncommon condition of the external auditory canal (EAC). It is a cholesteatoma-like mass found filling the deep EAC. The pathogenesis of KO has not fully understood, but the fault in auditory epithelium was the basis of the condition.[1] In KO, there is progressive accumulation of keratin on the tympanic membrane.[2] The exuberant accumulation of desquamated skin may produce bony erosion and gradual expansion of the bony EAC.[3]

Tympanometry is a measure of variation of the acoustic impedence of the tympanic ossicular system caused by pressure variations introduced into the EAC.[4] It provides useful quantitative information about the ear canal volume, mobility of the middle ear system, and presence of fluid in the middle ear. In short, tympanogram describes the flexibility of the tympanic membrane and therefore has a single reading. We report a case of double-peak tympanometry findings as a sequelae of KO.


  Case Report Top


A 32-year-old Chinese woman presented with a history of left ear pain and discharge for a few months. On further questioning, she claimed to have reduce hearing for the past few years which was more on the left. Otherwise, no history of tinnitus or vertigo was observed.

On examination, there was pus discharge that mixed with blood in the left ear canal. There was the presence of polyp at the roof of the canal and keratin debris accumulating and obstructing the tympanic membrane. Impacted hard wax was noted in the deep of right ear canal also obscuring the tympanic membrane. There was no abnormality noted on the examination of both nostrils, intraorally, and neck. She was started on ofloxacin ear drops for the left ear and repeated ear toilets were done for both ears. On further follow-up, examination of the left ear revealed a dilated medial part of the external canal with a seen through thinning of the posterosuperior wall but with intact tympanic membrane [Figure 1]. Examination of the right ear showed expanded medial part of the external canal with intact tympanic membrane. Tuning fork tests revealed negative Rinne test on the left and Weber test was lateralized to the left. Pure tone audiogram showed an average of 35 dB conductive hearing loss on the left ear while normal hearing on the right. Tympanometry which has been done in two different follow-up appointments revealed a double peak with large canal volume on the left ear [Figure 2]. The right ear has normal compliance but with slight increase in the canal volume. Computed tomorgrphy scan done showed expansion and erosion of the medial part of the left EAC [Figure 3]. Her right and left ear condition was controlled after 6 months and 18 months of follow-up, respectively.
Figure 1: Left external ear canal showing a seen through thinning of its posterosuperior wall

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Figure 2: Tympanogram showing double peak admittance and very large canal volume on the left ear

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Figure 3: Computed tomography scan showing expansion and erosion of the medial part of left external auditory canal

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  Discussion Top


KO is a disorder of keratin formation and is described as accumulation of desquamated keratinous material in the bony portion of the EAC.

It shares common characteristics as EAC cholesteatoma, except that it predominantly occurs in younger age group and all lesions in KO are circumferential and occur in both ears.[5] Both diseases can cause acute otalgia, otorrhoea, and hearing loss. The gradual expansion of the bony EAC was well demonstrated in our patient. Her symptoms were well managed and controlled with regular cleaning and suctioning of the keratin and debris in the EAC.

Tympanometry is an effective tool for early identification of changes in the external ear and middle ear. Tympanometric curves usually classified as Type A, Type B, Type C, Type As, and Type Ad. Type A tympanogram means a normal pressure in the middle ear with normal mobility of the ear drum and the conduction bones. In Type B, the curve is flat with no admittance peak, Type C has admittance peak shifted to negative pressure, Type As is curve with low admittance, and in Type Ad, there is the presence of interval between two branches of curve ≥100 daPa.[4] Type B and Type C tympanograms may be resulted from fluid in the middle ear, perforation or scarring of the tympanic membrane, lack of contact among the conduction of middle ear, or a tumour in the middle ear. As the measurement is related to the pressure immobilization of the tympanic membrane, it will produce a single peak.

From the tympanometry of our case that was done in two separate occasions, the left ear canal volume was high. It can be explained by the expansion of the ear canal due to KO. Apart from that, the tympanometry result was double curve. The second curve has a high but with more negative admittance peak. This result was consistent on repeated tympanometry on further follow-up. This signifies that there was a second tympanic membrane or pseudomembrane which was very mobile. If these tympanometry findings are correlated with the examinations, the thin posterosuperior wall of the EAC acts as the secondary tympanic membrane/pseudomembrane and produces the second admittance peak in the tympanometry. To the best of the authors' knowledge, there are no reported cases of double-curve tympanometry occurring in adults in English literature. However, there were cases of double-peak tympanogram found in neonates and infants.[6],[7] Soft external ear canal may be the reason for the finding in these groups of children.


  Conclusion Top


Double-peak admittance with huge canal volume in tympanometry may be seen in diseases causing erosion and expansion of EAC. Double-peak tympanometry with an intact tympanic membrane may indicate diseases causing severe erosion in the EAC.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their 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

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Corbridge RJ, Michaels L, Wright T. Epithelial migration in keratosis obturans. Am J Otolaryngol 1996;17:411-4.  Back to cited text no. 1
    
2.
Soucek S, Michaels L. Keratosis of the tympanic membrane and deep external auditory canal. A defect of auditory epithelial migration. Eur Arch Otorhinolaryngol 1993;250:140-2.  Back to cited text no. 2
    
3.
Piepergerdes JC, Kramer BM, Behnke EE. Keratosis obturans and external auditory canal cholesteatoma. Laryngoscope 1980;90:383-90.  Back to cited text no. 3
    
4.
Carmo MP, Costa NT, Momensohn-Santos TM. Tympanometry in infants: A study of the sensitivity and specificity of 226-hz and 1,000-hz probe tones. Int Arch Otorhinolaryngol 2013;17:395-402.  Back to cited text no. 4
    
5.
Persaud R, Chatrath P, Cheesman A. Atypical keratosis obturans. J Laryngol Otol 2003;117:725-7.  Back to cited text no. 5
    
6.
Zhiqi L, Kun Y, Zhiwu H. Tympanometry in infants with middle ear effusion having been identified using spiral computerized tomography. Am J Otolaryngol 2010;31:96-103.  Back to cited text no. 6
    
7.
Kei J, Allison-Levick J, Dockray J, Harrys R, Kirkegard C, Wong J, et al. High-frequency (1000 hz) tympanometry in normal neonates. J Am Acad Audiol 2003;14:20-8.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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