The challenges of respiratory motor system recovery following cervical spinal cord injury.

High cervical spinal cord injury (SCI) typically results in partial paralysis of the diaphragm due to intrusion of descending inspiratory drive at the level of the phrenic nucleus. The degree to which such paralysis occurs depends on the type, force, level, and extent of trauma produced. While endogenous recovery and plasticity may occur, the resulting respiratory complications can lead to morbidity and death. However, it has been shown that through modification of intrinsic motor neuron properties, or altering the environment localized at the site of SCI, functional recovery and plasticity of the respiratory motor system can be facilitated. The present review emphasizes these factors and correlates it to the treatment of SCI at the level of the somatic nervous system. Despite these promising therapies, functional respiratory motor system recovery following cervical SCI is often minimal. This review thus focuses on possible directions for the field, with emphasis on combinatorial treatment.