Protective effect of hyperbaric oxygen therapy on experimental brain contusions.

BACKGROUND: We evaluated the effect of hyperbaric oxygen therapy (HBO) on experimental brain contusions in rats using magnetic resonance imaging (MRI). MATERIALS AND METHODS: Ten Sprague-Dawley rats were investigated at 24 h and 72 h after controlled cortical impact injury. One hour after trauma, 5 rats were treated for 60 min with 100% oxygen at 2.5 absolute atmosphere (ATA), 5 were kept at normobaric room air. MRI was performed longitudinally at 24 h and 72 h after injury. Lesion volume was determined in T2 weighted MRI scans. Relative apparent diffusion coefficient (ADC) changes were calculated in comparison to the contralateral side. RESULTS: Following HBO, T2 lesion volume was smaller at 24 h versus controls (63.1 +/- 16.5 mm3 vs. 87.4 +/- 13.8 mm3, p < 0.05), and decreased further at 72 h (46.8 +/- 17.8 mm3 vs. 92.5 +/- 13.1 mm3, p < 0.01). At 24 h, the mean relative ADC change in the lesion area decreased from + 26.8 +/- 2.3% in controls to + 2.3 +/- 12.2% in HBO animals (p < 0.01). At 72 h, the HBO effect on relative ADC values was less when compared to 24 h. DISCUSSION: A 60-minute exposure to hyperbaric oxygen starting 1 h after impact injury significantly attenuated lesion growth and relative increase of ADC values within the contused area for up to 72 h. Thus, a "single-shot" HBO treatment seems to have long-lasting neuroprotective effects on the contused brain and its penumbra.