Detrimental Effects of Systemic Hyperthermia on Locomotor Function and Histopathological Outcome after Traumatic Spinal Cord Injury in the Rat

Abstract

OBJECTIVE: Posttraumatic hyperthermia has been demonstrated to worsen neurological outcome in models of brain injury. The purpose of this study was to examine the effects of systemic hyperthermia on locomotor and morphological outcome measures after traumatic spinal cord injury (SCI) in the rat. METHODS: After a T10 laminectomy, spinal cord contusions were produced from a height of 12.5 mm onto exposed cords (NYU Impactor; New York University Neurosurgery Laboratory, New York, NY) in adult rats that were divided into three groups. Group 1 (n = 9) underwent whole body hyperthermia (rectal temperature, 39.5 degrees C) 30 minutes postinjury for 4 hours, Group 2 (n = 8) underwent normothermia (rectal temperature, 37 degrees C) 30 minutes postinjury for 4 hours, and Group 3 (n = 10) underwent traumatic SCI with no postinjury thermal treatment. Twice-weekly assessments of locomotor function were made during a 6-week survival period using the Basso-Beattie-Breshnahan locomotor rating scale. Forty-four days after injury, animals were perfused, and their spinal cords serially sectioned. Sections were stained with hematoxylin, eosin, and Luxol fast blue for histopathological analysis. The percentage of tissue damage was quantitatively determined by using computer-aided image analysis. RESULTS: The results showed that 4 hours of postinjury hyperthermia significantly worsened locomotor outcome (final Basso-Beattie-Breshnahan scores were 9.7 +/- 0.3 [Group 1] versus 10.8 +/- 0.4 [Group 2] versus 11.3 +/- 0.3 [Group 3]) and led to an increase in the percentage of tissue damage (32.9 + 3.2% [Group 1] versus 22.3 +/- 2.8% [Group 3]). CONCLUSION: These data suggest that complications of SCI (e.g., fever, infection) leading to an elevation of systemic temperature may add to the severity of secondary injury associated with traumatic SCI and significantly affect neurological outcome.