Tuberculous brain abscesses: Case series and review of literature

INTRODUCTION: Tuberculous brain abscess (TBA) is a rare but serious condition. It resembles a pyogenic brain abscess clinically and radiologically and poses a problem in diagnosis and treatment. A final diagnosis is established by smear or culture demonstration of acid fast bacilli (AFB) within the abscess. Here, we report four such cases in our five-year study on brain abscesses, along with the different diagnostic modalities used. MATERIALS AND METHODS: A total of 75 brain abscess pus specimens were collected during neurosurgery, either by burr hole or by craniotomy. These specimens were further subjected to Gram stain, Ziehl-Neelsen (ZN) stain, and conventional microbiological culture. Only those cases which showed presence of AFB on ZN stain along with the growth of Mycobacterium tuberculosis were considered as TBAs. Such TBA cases were further presented along with their In vitro Proton Magnetic Resonance (MR) Spectroscopic findings. RESULTS: Of these four patients, three were males. Though this condition is more commonly seen in immunocompromised patients, three of the patients in this study were immunocompetent. All the four pus specimens showed presence of AFB in the ZN stain. Three of them grew M. tuberculosis as sole isolate. The fourth case was of concomitant tuberculous and pyogenic brain abscess. In vitro Proton MR spectroscopy of the pus specimens showed absence of multiple amino acids at 0.9 ppm, which was found to be hallmark of TBA. One patient died of four. CONCLUSIONS: TBA always poses a diagnostic dilemma. ZN stain and conventional microbiological culture for Mycobacteria always help to solve this dilemma. In vitro Proton MR Spectroscopy also seems to have the diagnostic utility.