Anesthesia influences the outcome from experimental spinal cord injury

The effect of anesthesia upon the functional outcome after experimental spinal cord injury (SCI) was studied in 221 rats subjected to graded weight drop contusion in the thoracic cord. Neurologic function was assessed in a blinded fashion for one week after injury using a modification of the method of Tarlov. The post-mortem concentrations of serotonin and its metabolite were measured in injured and surrounding spinal tissues in a subset of animals in order to estimate the survival of descending long-tract axons. In initial studies using non-ventilated animals where body temperature was not controlled (n = 130), halothane anesthesia was associated with significantly better neurologic scores at all levels of injury (50, 100 and 250 g.cm) in comparison to pentobarbital. In a second experiment under these conditions (n = 53) the effect of halothane was observed after a 50 g.cm injury in comparison to both pentobarbital and nitrous oxide. Improved neurologic recovery was accompanied by the preservation of normal serotonin and metabolite concentrations in spinal tissue caudal to the site of injury. These values did not differ from those measured in sham-operated animals. Separate experiments (n = 12) revealed halothane's preservation of somatosensory-evoked responses during the early postinjury period in animals showing improved neurologic recovery. Subsequent experiments (n = 12) were performed to assess the effect of oxygen supplementation and the control of rectal temperature and a separate series of acute experiments (n = 14) examined arterial blood pressure responses to injury in halothane- and pentobarbital-anesthetized animals.(ABSTRACT TRUNCATED AT 250 WORDS)