[Effect of mannitol administration and myelotomy on acute experimental spinal cord injury: investigation by spinal cord evoked potential].

The authors reported the changes in spinal cord evoked potential following impact injury by the weight-dropping technique in untreated and treated animals. The effect of mannitol and myelotomy therapy on spinal cord evoked potential in experimental spinal cord injury was discussed. (Materials and Methods) 32 adult dogs, ranging in weight from 9 to 13 kg, were used. 28 dogs received 300 gm-cm contusion of the T10 spinal cord. Eight dogs were not treated and twenty dogs were treated with mannitol. Ten dogs were treated with intravenous continuous infusion of mannitol (1g/kg/hr) 30 minutes after the injury, and ten dogs with intravenous bolus injection of mannitol (2 g/kg) at 30 minutes and 3 hours after the injury. At one hour after the injury, five dogs with 400 gm-cm contusion were treated with posterior midline myelotomy. The spinal cord evoked potential following direct stimulation of the spinal cord was recorded from the epidural space for 5 hours. The recording electrode was located cephalad to the site of the impact injury. (Results and Discussion) In each group, the amplitude of I potential decreased remarkably immediately after the injury. Subsequently, gradual recovery was obtained. In the untreated 300 gm-cm contusion group, no apparent improvement was seen from one hour after injury. On the other hand, in the mannitol-treated group, the recovery of the amplitude was superior to that found in the untreated group at a significant level of P less than 0.05. However, in the group with intravenous bolus injection of mannitol, the recovery was transient.(ABSTRACT TRUNCATED AT 250 WORDS)