External auditory canal atresia (EACA) is characterised by complete or incomplete bony atresia of the external auditory canal (EAC) and, especially when seen in the setting of an associated syndrome, a dysplastic auricle and abnormal middle ear cavity.
Demographics and clinical presentation
The incidence is 1 in 10,000 - 20,000 births 2, with associated abnormal external ear and conductive hearing loss present from birth. Bilateral involvement is seen in approximately 1/3 of patients 2.
Although frequently isolated (in which case the abnormality is less severe and isolated to the EAC) a number of syndromes are associated with external auditory canal atresia 2. These include:
The EAC may be completely absent (see cases 1 and 2) or incompletely atretic with further narrowing contributed to by soft tissue bands.
Findings in the middle ear are variable and the inner ear and inner auditory canal are typically normal.
EAC atresia may be complicated by congenital cholesteatoma formation behind the atresia plate or in the middle ear.
A number or key points should be looked for and specifically mentioned in reports as it impacts on surgical reconstruction.
- middle ear cavity volume : a width of greater than 3 mm is usually needed for successful surgery
- ossicles 2
inner ear structure
- both the oval and round window need to be present for successful surgery
- course of internal carotid artery, and location of the jugular bulb: if abnormal can be hazardous during surgery
- course of facial nerve: often abnormally anterior and can be damaged during reconstruction.
Surgical reconstruction requires formation of a new EAC and new tympanic membrane (usually with temproalis facia). The ossicles often need to be mobilized.
- 1. Chakeres DW, A Kapila and D LaMasters. “Soft-tissue abnormalities of the external auditory canal: subject review of CT findings.” Radiology 156, no. 1 (July 1, 1985): 105-109.
- 2. Gassner Eva Maria, Ammar Mallouhi and Werner R. Jaschke. “Preoperative Evaluation of External Auditory Canal Atresia on High-Resolution CT.” Am. J. Roentgenol. 182, no. 5 (May 1, 2004): 1305-1312.
Synonyms & Alternative Spellings
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|External Auditory Canal Atresia||✗|
|External auditory canal atresia (EACA)||✗|