Hyperbaric oxygen is effective in early stage of healing of experimental brain abscess in rats Ivica Bilic 1 , Nadan M. Petri 2 , Mira Krstulja 3 , Meri Vuckovic 4 , Ilza Salamunic 5 , Katarina Sisko Kraljevic 6 , Vesna Capkun 7 , Ivo Lusic 1 1 Department of Neurology, University Hospital Center Split, Croatia, 2 Naval Medical Institute Split, Croatia, 3 Department of Pathology, University Hospital Center Rijeka, Croatia, 4 Department of Ophthalmology, General Hospital Dubrovnik, Croatia, 5 Department for Laboratory Diagnostics, University Hospital Center Split, Croatia, 6 Department of Microbiology, University of Split School of Medicine, Split, Croatia, 7 Department of Nuclear Medicine, University Hospital Center Split, Croatia Objectives: Current therapy of brain abscess (BA) includes a combined approach that involves antibiotics and minimal invasive surgery, but also hyperbaric oxygen treatment (HBOT) as a supportive measure. Optimum treatment is still a matter of significant controversy. Methods: The experiment, previously approved by a relevant ethical committee, involved 80 female Wistar rats. BA was experimentally induced by inoculation of Staphyloccocus aureus. The animals were randomized into groups and treated either with antibiotics, HBOT, or with a combination of both. Results: Beneficial effect of HBOT was evident in groups treated with HBOT or with a combination of antibioticzHBOT. It was mainly manifested on days three and five of the experiment and was evident as statistically significant increase of a number of newly formed blood vessels, increase in mean vascular density, and smaller abscess necrotic core. Discussion: Although the results of the present study should be interpreted cautiously, they suggest that HBOT has an important but limited role in the treatment of BA. Keywords: Brain abscess, Experimental model, Healing, Hyperbaric oxygen, Neoangiogenesis, Staphyloccocus aureus Introduction Brain abscess (BA) is a focal intracerebral infection caused by inflammation and collection of infected material originating from either local or remote source. It may also be introduced through a skull fracture or after surgical procedures. Until the late nineteenth century, BA was almost always fatal. 1 Although BA can occur in any age or gender, it occurs most frequently in men 30 to 50 years old. 2 The mortality rate reported in the late 1970s ranged from 29 to 53%. 3 During the years 1987–1993, the mortality may have decreased slightly, with a summed death rate of 20%. 4–6 Despite advances in diagnostics and therapy, nowadays average mortality still remains between 17 and 32%. 7 Neurologic sequellae could be present in 30–55% of survivors. 8 Clinical symptoms are hardly specific for BA, but a headache is most consistently the primary presenting symptom. Clinical course varies from indolent to fulminant. Confusion, altered level of consciousness and signs of increased intracranial pressure may be found. Furthermore, physical examination would most often not result in any detail specific for BA. No laboratory data could be considered pathogno- monic of BA. Normal leukocyte counts are frequently found, and the erythrocyte sedimentation rate is usually elevated, but sometimes normal. Blood cul- tures are very often negative but may sometimes yield the causing agent and therefore should be performed. Although potentially dangerous and most often not useful, lumbar puncture could be of value in excluding bacterial origin. Examination of cerebrospinal fluid usually shows a non-specific elevated protein level and cell count, and cerebrospinal fluid cultures are positive only in rare cases. C-reactive protein (CRP) is a non- specific test in diagnosis of BA. 1,2,7 BA is diagnosed by CT, MRI and/or biopsy. It most commonly appears as contrast ring-enhancing lesions so differential diagnosis includes different types of malignant and benign tumors (most com- monly metastatic ones), demyelinating processes, resolving hematomas, radiation necrosis and para- sitic intracerebral infections such as cysticercosis. 1,2,7 Best therapy of BA is still a challenge and increasingly complicated. Current approach usually Correspondence to: Ivica Bilic, Department of Neurology, University Hospital Center Split, Croatia. Email: ibilic@kbsplit.hr ß W. S. Maney & Son Ltd 2012 DOI 10.1179/1743132812Y.0000000091 Neurological Research 2012 VOL. 34 NO. 10 931