Treatment of bacterial brain abscess by repeated aspiration--follow up by serial computed tomography

Bacterial brain abscess often requires repeated aspiration before the abscess finally resolves. However, there are no guidelines for treatment by aspiration; for example, when should the abscess be tapped again, or when can an abscess be treated by antibiotics alone without further aspiration. Eleven patients with bacterial brain abscess treated by aspiration were evaluated to establish treatment guidelines for brain abscess, in particular the abscess size on serial computed tomography (CT) after aspiration. CT was performed about 24 hours after aspiration to evaluate the size of the abscess, and almost weekly during follow up. The diameter of the brain abscess before and after the initial and last aspirations were reviewed. In eight of the 11 patients, abscesses were aspirated repeatedly: two to three times in most patients. The diameter of the abscesses was 2.5-4.5 cm (mean 3.5 cm) before the last aspiration, and 1.4-3.4 cm (mean 2.3 cm) after the last aspiration, or when continuous drainage was discontinued. Perifocal edema was moderately decreased within 3 weeks after the last aspiration by medical treatment alone, with a concomitant decrease in the volume of the abscess. There were no deaths, and most patients had a favorable outcome. These results suggest that after the diameter of the abscess becomes less than 2 to 3 cm and does not increase anymore on serial CT, medical treatment alone can be anticipated to give satisfactory results without further aspiration.