Article

Neural plasticity may contribute to motor recovery following spinal
cord injury (SCI). In rat models of SCI with respiratory impairment, acute
intermittent hypoxia (AIH) strengthens synaptic inputs to phrenic motor neurons,
thereby improving respiratory function by a mechanism known as respiratory
long-term facilitation. Similar intermittent hypoxia-induced facilitation may be
feasible in somatic motor pathways in humans. OBJECTIVE: Using a randomized
crossover design, the authors tested the hypothesis that AIH increases ankle
strength in people with incomplete SCI. METHODS: Ankle strength was measured in
13 individuals with chronic, incomplete SCI before and after AIH. Voluntary ankle
strength was estimated using changes in maximum isometric ankle plantar flexion
torque generation and plantar flexor electromyogram activity following 15 low
oxygen exposures (Fio(2) = 0.09, 1-minute intervals). Results were compared with
trials where subjects received sham exposure to room air. RESULTS: AIH increased
plantar flexion torque by 82 +/- 33% (P < .003) immediately following AIH and was
sustained above baseline for more than 90 minutes (P < .007). Increased ankle
plantar flexor electromyogram activity (P = .01) correlated with increased torque
(r(2) = .5; P < .001). No differences in plantar flexion strength or
electromyogram activity were observed in sham experiments. CONCLUSIONS: AIH
elicits sustained increases in volitional somatic motor output in persons with
chronic SCI. Thus, AIH has promise as a therapeutic tool to induce plasticity and
enhance motor function in SCI patients.

Langue : ANGLAIS