Methylprednisolone treatment of acute spinal cord injury: an introduction.

Contusion injuries of cat spinal cords rapidly block action potential conduction across the impact site. Ion-selective microelectrode measurements revealed large and immediate extracellular ionic derangements, sufficient to block conduction. As extracellular potassium recovers, evoked potentials often return but are lost again when white matter blood flow fall. The delayed decline of evoked potentials and blood flow suggest secondary injury processes that may respond to pharmacological therapy. High dose methylprednisolone (15-30 mg/kg) dramatically improved blood flow, extracellular ionic shifts, blood flow, and evoked potentials in cat spinal cords. Methylprednisolone also decreased tissue ionic shifts and improved locomotory recovery. In concomitant experiments, we showed that naloxone also prevented posttraumatic declines in blood flow and improved locomotory recovery. Examination of the spinal cords at 6-12 weeks after injury, revealed that many recovered animals had only 10% of spinal cord axons remaining. Other studies revealed that many axons surviving injury are demyelinated, suggesting that drugs that protect oligodendroglial cells may also have beneficial effects.