Otitis externa

Overview & Definition

A mother brings her eight-year-old to the emergency department after a week of swimming lessons: two days of worsening ear pain, a mucky discharge, and a child who cries when the ear is touched. Pull gently on the pinna and press the tragus, and she flinches — that is the canal, not the middle ear, and it changes everything that follows. The fellowship skill in otitis externa is to localise the disease to the external canal, classify its form, treat it topically, and never miss the one form that invades the skull base. [1] [4]

Otitis externa is inflammation of the skin and subcutaneous tissue of the external auditory canal, from the conchal bowl and meatus in to the tympanic membrane. It is one of the commonest ear complaints of childhood, peaking in swimmers and in hot, humid weather, and it is overwhelmingly manageable in primary care with topical therapy. The term spans a spectrum: the common acute diffuse swimmer's ear, a localised furuncle, an eczematous or dermatitic canal, a fungal (otomycotic) infection, the chronic low-grade form, and the rare but dangerous necrotising (malignant) form that invades the skull base. [1] [3]

What makes the topic examinable is that the same canal anatomy produces behaviours ranging from trivial to life-threatening. Most otitis externa is a surface problem fixed by drops and drying; necrotising otitis externa is a deep, destructive osteomyelitis that needs weeks of systemic therapy and carries real mortality. The clinical hinge between them is the host and the depth of invasion: the well child has a surface infection, while the diabetic or immunocompromised child is the one in whom Pseudomonas reaches bone. Recognising that distinction at the bedside is the point of the topic. [7] [8]