Diagnostic problems in brain abscess: 45 cases reviewed

Background and purpose. - We analysed the difficulties encountered in the d ifferential diagnosis between brain abscess and brain tumor and their influ ence on treatment and outcome. Methods. - Forty-five adults with brain abscess operated on between 1993 an d 1999 were retrospectively reviewed. We studied preoperative diagnosis, cl inical, radiological, bacteriological findings, surgical procedure, prinzar y sources of infection and outcome. Results. - Preoperative diagnosis was right in 55.6 % (25/45), wrong in 22. 2 % (10/45) and doubtful in 22.2 % (10/45). Diffusion-weighted MR imaging w as successfully used in 4 doubtful cases to make the differential diagnosis between abscess and tumor. When the preoperative diagnosis was right, the surgical procedure was a burr-hole aspiration in 73.3 % (22/25) whereas whe n it was wrong, an excision was performed in 60 % (6/10) of the cases. Aspi ration was the last diagnostic investigation in 80 % (8/10) of doubtful cas es. Microbacterial organisms were identified in 75.5 % (34/45) of the cases and primary cause of infection in 62.2 % (28/45). The outcome depended on clinical status on admission, preoperative diagnosis and surgical procedure . In four cases, diffusion-weighted MRI allowed differential diagnosis betw een brain abcess and tumor through calculation of the Apparent Diffusion Co efficient which is low in abscess and high in cystic tumor. Conclusion. - The diagnosis of brain abscess remains difficult in certain p atients. Correct preoperative diagnosis influences the decision on the appr opriate surgical procedure and helps improve outcome.