Tissue pressure gradients in spinal cord injury

Using cotton wick catheters, local tissue pressure was measured in the dorsal white matter of the impacted feline spinal cord. Twenty gram and 30 gram weights dropped 20 cm did not produce statistically significant elevations in tissue pressure adjacent to and remote from the site of injury. Forty gram weights dropped 20 cm produced pressure gradients of less than 10 mmHg between areas near and remote from the injury and between parenchyma and cerebrospinal fluid. In a group studied 18-24 hours after similar injuries, no gradients were found, although edema formation as indicated by Evan's blue migration had progressed. These findings indicate that gradients of pressure within parenchyma are associated with edema spread following high impaction forces and that edema spread can continue after dissipation of these gradients.