Hyperbaric Oxygen Therapy After Acute Thoracic Spinal Cord Injury: Improvement of Locomotor Recovery in Rats.

STUDY DESIGN: A controlled laboratory study. OBJECTIVE: The aim of this study was to analyze the effectiveness of hyperbaric therapy (HT) using mild and moderate models of spinal cord injury (SCI). SUMMARY OF BACKGROUND DATA: SCI can cause permanent impairment with socioeconomic consequences. The motor deficit occurs by two mechanisms: destruction of neuronal cells and local inflammatory response, resulting in hypoxia. HT acts by increasing oxygen in the injured area. METHODS: Thoracic laminectomy was performed in 72 female Wistar rats. The MASCIS impactor was used at 12.5 mm (n = 35) and 25 mm (n = 35) of height to perform, respectively, mild and moderate SCI. Muscle strength was assessed through the Basso, Beattie, and Bresnahan scale (BBB) on days 1, 7, 14, 21, and 28 after SCI. The animals were randomized into five subgroups with seven animals each: (1) control group had SCI without HT; (2) HT 30 minutes after SCI; (3) HT 30 minutes after SCI and daily for 7 days; (4) HT 12 hours after SCI; and (5) HT 12 hours after SCI and daily for 7 days. HT was performed at 2.5 atm for 1 hour. RESULTS: There was a linear relationship between injury severity and motor deficit until day 21, with similar BBB scores on day 28. A pattern of uniform lesions was observed in the mild SCI, with lower variation of BBB when compared with moderate SCI. All animals that underwent HT had significant improvement in motor function and histology when compared with control group. Regardless of the injury model, animals submitted to 7-day protocols had an early improvement in motor function and a smaller area of histological injury. CONCLUSION: The present study reported that the sooner HT is begun after mild and moderate SCI and the larger the number of sessions, the greater and earlier is the motor recovery and smaller is the tissue injury. LEVEL OF EVIDENCE: N/A.