The Xexion reXex modulation pattern was investigated in nine people with a chronic spinal cord in... more The Xexion reXex modulation pattern was investigated in nine people with a chronic spinal cord injury during stepping using body weight support on a treadmill and manual assistance by therapists. Body weight support was provided by an upper body harness and was adjusted for each subject to promote the best stepping pattern with the least manual assistance required by the therapists. The Xexion reXex was elicited by sural nerve stimulation with a 30 ms pulse train at 1.2-2 times the tibialis anterior reXex threshold. During stepping, stimuli were randomly dispersed across the gait cycle which was divided into 16 equal bins. A long latency (>110 ms) Xexion reXex was present in all subjects, while a short (>30 ms) and a medium latency (>70 ms) Xexion reXex were present only in three subjects. For each response, the non-stimulated EMG was subtracted from the stimulated EMG at identical time windows and bins, normalized to the maximal corresponding EMG, and signiWcant diVerences were established with a Wilcoxon rank-sum test. The long latency Xexion reXex was facilitated at late stance and during the swing-tostance transition phase. A reXex depression was present from heel strike until mid-stance and during the swing-tostance transition phase. The short and medium latency Xexion reXexes were depressed during mid-stance followed by facilitation during the stance-to-swing transition phase. Regardless of the latency, facilitatory Xexion responses during the swing phase coincided with decreased activity of ipsilateral ankle extensors. The Xexion reXex was modulated in a phase dependent manner, a behavior that was absent for the soleus H-reXex in most of these patients (Knikou et al. in Exp Brain Res 193:397-407, 2009). We propose that training should selectively target spinal reXex circuits in which extensor muscles and reXexes are involved in order to maximize sensorimotor recovery in these patients.
The Xexion reXex modulation pattern was investigated in nine people with a chronic spinal cord in... more The Xexion reXex modulation pattern was investigated in nine people with a chronic spinal cord injury during stepping using body weight support on a treadmill and manual assistance by therapists. Body weight support was provided by an upper body harness and was adjusted for each subject to promote the best stepping pattern with the least manual assistance required by the therapists. The Xexion reXex was elicited by sural nerve stimulation with a 30 ms pulse train at 1.2-2 times the tibialis anterior reXex threshold. During stepping, stimuli were randomly dispersed across the gait cycle which was divided into 16 equal bins. A long latency (>110 ms) Xexion reXex was present in all subjects, while a short (>30 ms) and a medium latency (>70 ms) Xexion reXex were present only in three subjects. For each response, the non-stimulated EMG was subtracted from the stimulated EMG at identical time windows and bins, normalized to the maximal corresponding EMG, and signiWcant diVerences were established with a Wilcoxon rank-sum test. The long latency Xexion reXex was facilitated at late stance and during the swing-tostance transition phase. A reXex depression was present from heel strike until mid-stance and during the swing-tostance transition phase. The short and medium latency Xexion reXexes were depressed during mid-stance followed by facilitation during the stance-to-swing transition phase. Regardless of the latency, facilitatory Xexion responses during the swing phase coincided with decreased activity of ipsilateral ankle extensors. The Xexion reXex was modulated in a phase dependent manner, a behavior that was absent for the soleus H-reXex in most of these patients (Knikou et al. in Exp Brain Res 193:397-407, 2009). We propose that training should selectively target spinal reXex circuits in which extensor muscles and reXexes are involved in order to maximize sensorimotor recovery in these patients.
Uploads
Papers by Claudia Angeli