Acute and acute-on-chronic mastoiditis (a five-year experience at Groote Schuur Hospital).

One hundred and thirty patients with acute-on-chronic mastoiditis were managed by the ENT Department of Groote Schuur Hospital between 1980 and 1984 inclusive. Seventy-four patients had cholesteatomas, of whom 78.4 per cent had intracranial extension and 44.6 per cent had intradural extension of the infection. In contrast, of the 56 patients without cholesteatomas, only 23.2 per cent had intracranial extension of the infection. These may be rare conditions in some privileged parts of the world but their lethal potential requires all ENT surgeons to be competent in their management.