Cerumen, also known as earwax, is a natural secretion produced by, and found within the external auditory canal (EAC). It has important roles as part of the first-line of defense of the ear from micro-organisms and optimising function of the tympanic membrane and EAC.
Cerumen is secreted by the ceruminous glands, in concert with the sebaceous glands. The ceruminous glands are a specialized subtype of apocrine (sweat) glands, with approximately 1,000 to 2,000 within the lining of each external ear canal.
Two main forms of cerumen have been identified 1:
- a watery brownish-yellow wax, primarily found in Caucasian and African populations
- a drier white form, primarily found in Eastern Asian and native American populations
Cerumen has a variety of functions including:
- lubrication and waterproofing of the external ear canal, maintaining optimal tympanic membrane suppleness
- trapping foreign material e.g. fungal spores, bacteria, dust
- antibacterial properties
Cerumen may mimic a pathological lesion in the external ear canal on CT. It generally has fatty attenuation with a rim of air (see Case 1) 3. If there is any doubt then direct visual inspection will usually clarify its nature.
- 1. Prokop-Prigge KA, Thaler E, Wysocki CJ, Preti G. Identification of volatile organic compounds in human cerumen. (2014) Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. 953-954: 48-52. doi:10.1016/j.jchromb.2014.01.043 - Pubmed
- 2. Richard Coppin, Dorothy Wicke, Paul Little. Managing earwax in primary care: efficacy of self-treatment using a bulb syringe. (2008) Br J Gen Pract. 58 (546): 44. doi:10.3399/bjgp08X263811 - Pubmed
- 3. Lesions in the external auditory canal. (2011) Indian Journal of Radiology and Imaging. 21 (4): 274. doi:10.4103/0971-3026.90687 - Pubmed
- 4. Guest JF, Greener MJ, Robinson AC, Smith AF. Impacted cerumen: composition, production, epidemiology and management. (2004) QJM : monthly journal of the Association of Physicians. 97 (8): 477-88. doi:10.1093/qjmed/hch082 - Pubmed