Aetiology and Pathogenesis of Otitis Externa . . . . . . . . . . . . . . . . . Concept of primary and secondary factors, predisposing factors, and

August1 proposed that the approach to otitis externa should not be considered symptomatically, but through the identifi­ cation and management of three factors. He proposed a triad of primary, predisposing, and perpetuating factors. Although this system provided a basis for investigation and treatment of ear disease for many years it has more recently been superseded by the PSPP System2: • Primary (P) and Secondary (S) causes

are diseases or infectious agents that directly cause inflammation in the ear.