Responses of the Acutely Injured Spinal Cord to Vibration that Simulates Transport in Helicopters or Mine-Resistant Ambush-Protected Vehicles.

In the military environment, injured soldiers undergoing medical evacuation via helicopter or mine-resistant ambush-protected vehicle (MRAP) are subjected to vibration and shock inherent to the transport vehicle. We conducted the present study to assess the consequences of such vibration on the acutely injured spinal cord. We used a porcine model of spinal cord injury (SCI). After a T10 contusion-compression injury, animals were subjected to 1) no vibration (n = 7-8), 2) whole body vibration at frequencies and amplitudes simulating helicopter transport (n = 8), or 3) whole body vibration simulating ground transportation in an MRAP ambulance (n = 7). Hindlimb locomotor function (using Porcine Thoracic Injury Behavior Scale [PTIBS]), Eriochrome Cyanine histochemistry and biochemical analysis of inflammatory and neural damage markers were analyzed. Cerebrospinal fluid (CSF) expression levels for monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6, IL-8, and glial fibrillary acidic protein (GFAP) were similar between the helicopter or MRAP group and the unvibrated controls. Spared white/gray matter tended to be lower in the MRAP-vibrated animals than in the unvibrated controls, especially rostral to the epicenter. However, spared white/gray matter in the helicopter-vibrated group appeared normal. Although there was a relationship between the extent of sparing and the extent of locomotor recovery, no significant differences were found in PTIBS scores between the groups. In summary, exposures to vibration in the context of ground (MRAP) or aeromedical (helicopter) transportation did not significantly impair functional outcome in our large animal model of SCI. However, MRAP vibration was associated with increased tissue damage around the injury site, warranting caution around exposure to vehicle vibration acutely after SCI.