Causes of Hard Earwax (Cerumen)
Hard earwax results from normal cerumen production in the outer two-thirds of the ear canal, but becomes problematic when the natural self-cleaning mechanism fails, leading to accumulation and impaction. 1
Normal Cerumen Physiology
Cerumen is a normal protective substance formed when glandular secretions from sebaceous and modified apocrine sweat glands in the outer two-thirds (cartilaginous portion) of the ear canal mix with sloughed epithelial cells. 1, 2 The ear canal has an elaborate self-cleaning mechanism where epithelial migration creates a "conveyor belt" effect, moving dead skin and cerumen outward with the help of jaw movement. 1, 2
Primary Causes of Cerumen Impaction
Patient-Related Risk Factors
Certain populations are at significantly higher risk for developing hard, impacted cerumen:
- Age extremes: Children (1 in 10), elderly adults (more than one-third), and cognitively impaired individuals have substantially higher rates of cerumen impaction. 1
- Developmental disabilities: Adults with mental retardation show a 28% incidence of excessive cerumen with associated conductive hearing loss, compared to only 2-6% in the general adult population. 3
- Hearing aid users: This population has a markedly higher incidence of impaction due to overstimulation of cerumen production and impairment of normal cleaning mechanisms. 1
Behavioral and Iatrogenic Causes
The most common modifiable cause of hard, impacted cerumen is improper ear cleaning practices:
- Cotton-tipped swabs and foreign objects: Rather than removing wax, these instruments push cerumen deeper into the canal, worsening impaction. 1 Children whose ears were cleaned with cotton-tipped swabs showed a higher incidence of cerumen accumulation. 1
- Insertion of various objects: Studies found that >90% of health workers inserted foreign objects (cotton buds, ballpoint pen covers, matchsticks, chicken feathers, bobby pins) into their ear canals, with approximately 9% reporting injuries including cerumen impaction. 1
Anatomic and Medical Factors
Specific anatomic and medical conditions predispose to hard cerumen:
- Narrow ear canals: Congenital or acquired narrowing limits natural migration and increases accumulation. 1
- Prior radiation therapy: Head and neck radiation causes histologic changes including epithelial thinning and atrophy of ceruminous glands, resulting in drier, more tenacious cerumen/keratin debris. 1
- Diabetes mellitus: The pH of diabetic cerumen is significantly higher than in non-diabetics, which may alter cerumen consistency and facilitate pathogen growth. 1
Clinical Implications
Understanding these causes is critical because cerumen impaction can cause hearing loss, ear fullness, tinnitus, itching, otalgia, and discharge. 4 In children, cerumen prevented diagnosis of acute otitis media in 29% of cases where it was subsequently removed. 1
Key Prevention Counseling Points
Clinicians should educate patients that:
- Cerumen is a normal protective substance that should be left alone unless causing symptoms or preventing examination. 1
- Cotton-tipped swabs and other objects should never be inserted into the ear canal, as they worsen impaction rather than remove wax. 1
- High-risk groups (elderly, hearing aid users, those with prior impaction history) may benefit from preventive measures. 1
- Hearing aids should be properly cleaned and maintained, as 60-70% of hearing aids sent for repair are damaged by cerumen contact. 1