The Reversal of Neuromuscular Adaptation in Human with Spinal Cord Injury---Effect of Fast Continuous Passive Motion (CPM) on Restoration of Pad and Muscle Contractile Properties

Following injury to the spinal cord, the spinal circuit undergoes a series of adaptations. In parallel with the spinal circuit adaptation, the muscular properties also adapt. In human and animal studies, histochemical and physiological evidences showed that the paralyzed muscle transferred from slow, fatigue-resistant to fast, fatigable after injury. The diminishing amounts of post activation depression of monosynaptic reflex were attributed to the spasticity symptom. The neuromuscular adaptations after SCI are possibly due to the absolute immobilization below the level of injury. Studies suggest that muscle has a default program to be fatigable type II fibers. Without neural activities, muscle converts to its default type. Therefore, Remobilization of the adapted neuromuscular structures and/or preventing neuromuscular structures from immobilization are reasonable rehabilitation approach. Remobilization by passive motions becomes possible due to the current progresses in robot assisted therapy. Previous studies found that fast continuous passive motion (CPM) altered the H reflex excitability in human. Animal studies found that passive cycling and passive stretching delayed muscle atrophy and influenced the transition of type I and IIa MHC. Theses findings lead to a hypothesis that mechanical stimulation might be able to reverse both spinal circuitry and muscular properties after SCI. This hypothesis needs to be confirmed in human study. The purpose of this project is to investigate the effect of remobilization by fast CPM on the reversing and preventing the immobilization adaptation of human paralyzed muscle and spinal circuitries. In three years, the following goals will be accomplished: 1. Establishing the sensitive and reliable non-invasive neuromuscular adaptation indicators 2. Investigating the effect of CPM on the reversal of neuromuscular adaptation in individuals with chronic SCI 3. Investigating the effect of CPM on muscles with different fiber type compositions. 4. Investigating the effect of CPM on prevention the neuromuscular adaptation in individuals with acute SCI The results of this project will advance the understanding of neuromuscular adaptation and restoration in humans after spinal cord injury and provide a valid approach in clinical rehabilitations.

Project ID:PC10007-0395
External Project ID:NSC100-2314-B182-005