Otitis Externa

Otitis externa is a diffuse, painful inflammation of the skin lining the external auditory canal. Moisture, instrumentation, and skin disease can disrupt the canal’s protective barrier. Swimming, repeated water exposure, cotton-tip swabs, earbuds, hearing aids, eczema, psoriasis, and seborrheic dermatitis are common contributors. Cerumen is more than debris. Its hydrophobic, mildly acidic coating helps limit microbial growth, while normal epithelial migration carries shed skin outward. Water softens and removes this barrier, and mechanical trauma creates small breaks in the skin. The resulting warm, damp canal favours bacterial growth, particularly Pseudomonas aeruginosa and Staphylococcus aureus. Inflammation then produces oedema and debris, narrowing the canal and making both examination and medication delivery more difficult. The inflammation explains the characteristic pain with movement. Manipulating the tragus or pinna pulls on the inflamed canal skin, whereas uncomplicated otitis media usually does not make the tragus markedly tender. Canal narrowing can also cause a blocked sensation or conductive hearing reduction. Most cases are uncomplicated and remain confined to the canal. Necrotizing otitis externa is different: infection extends into the deeper tissues and temporal bone, with...