Acute mastoiditis in a Norwegian population: a 20 year retrospective study.

We have retrospectively examined the nature of acute mastioditis (in western Norway) during a 20 year period (1980-2000). Sixty-one cases of AM were identified in 57 patients with a mean age of 3.6 years. We found no significant change in the incidence of AM during the last 20 years. Seven patients were treated solely with intravenous antibiotics and myringotomies. Fifty patients also underwent cortical mastoidectomy, four cases with bilateral surgery. Antibiotic treatment was given to 31 of the patients before admission to hospital and this group had a significant longer duration of symptoms (12.4 days) compared to untreated patients (7.3 days). Streptococcus pneumoniae was the most common organism recovered from patient cultures. Surgery was found to correlate to patients with retroauricular fluctuation or to children with at least two of the three clinical signs: protrusion of the ear, retroauricular oedema and swelling of the ear canal. Our data show that clinical examination only reveal 50% of the cases with surgically proven retroauricular subperiostal abscess. We therefore recommend a CT scan of patients treated conservatively.