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Flexion reflex modulation during stepping in human spinal cord injury.

Abstract：

:The flexion reflex 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 flexion reflex was elicited by sural nerve stimulation with a 30 ms pulse train at 1.2-2 times the tibialis anterior reflex threshold. During stepping, stimuli were randomly dispersed across the gait cycle which was divided into 16 equal bins. A long latency (>110 ms) flexion reflex was present in all subjects, while a short (>30 ms) and a medium latency (>70 ms) flexion reflex 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 significant differences were established with a Wilcoxon rank-sum test. The long latency flexion reflex was facilitated at late stance and during the swing-to-stance transition phase. A reflex depression was present from heel strike until mid-stance and during the swing-to-stance transition phase. The short and medium latency flexion reflexes were depressed during mid-stance followed by facilitation during the stance-to-swing transition phase. Regardless of the latency, facilitatory flexion responses during the swing phase coincided with decreased activity of ipsilateral ankle extensors. The flexion reflex was modulated in a phase dependent manner, a behavior that was absent for the soleus H-reflex in most of these patients (Knikou et al. in Exp Brain Res 193:397-407, 2009). We propose that training should selectively target spinal reflex circuits in which extensor muscles and reflexes are involved in order to maximize sensorimotor recovery in these patients.

journal_name

Exp Brain Res

journal_title

Experimental brain research

authors

Knikou M,Angeli CA,Ferreira CK,Harkema SJ

doi

10.1007/s00221-009-1854-x

subject

Has Abstract

pub_date

2009-07-01 00:00:00

pages

341-51

issue

eissn

0014-4819

issn

1432-1106

journal_volume

196

pub_type

杂志文章

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Flexion reflex modulation during stepping in human spinal cord injury.