Serial recording of reflexes after feline spinal cord transection.

Implanted nerve cuff and muscle electrodes were used to serially record reflexes after spinal cord transection in cat. Recording of reflexes, in response to both sensory nerve and to mixed motor and sensory nerve stimulation, was accomplished through 2 months after cord section. Serial recording of afferent and efferent nerve volleys was achieved as well. Serial reflex changes that follow cord transection are described. Reflex amplitude to sensory nerve stimulation increased in two phases. The first increase was noted between 1 and 4 days after cord transection; the second increase was recorded between 2 and 4 weeks. These observations suggest that at least two neuronal mechanisms with distinct temporal courses mediate the appearance of spinal hyperreflexia. The animal model described may be useful for further study of the neuronal mechanisms which underlie the hyperreflexia of spinal cord injury.