[Descending modulation of the reflex reactions of the spinal motor neurons in human spinal cord damage]

Changes of H-reflexes amplitude and Ia-inhibition intensity before, during and after voluntary contractions of skeletal muscles were studied in healthy subjects and patients with midthoracic injury of the spinal cord. The voluntary actions induced facilitation of H-reflexes and suppression of Ia inhibition in healthy people and in patients with paraparesis. In patients with paraplegia these voluntary actions induced either the depression of H-reflexes and increase of Ia inhibition intensity or caused no effect on these reactions. A relation between reflex reaction changes and posttraumatic structural and functional disturbance of descending paths were discussed.