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 mm(3) vs. 87.4 +/- 13.8 mm(3) p<0.05), and decreased further at 72 h (46.8 +/- 17.8 mm(3) vs. 92.5 +/- 13.1 mm(3), 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.