Soleus H-Reflex Modulation After Motor Incomplete Spinal Cord Injury: Effects of Body Position and Walking Speed

Abstract

Objective: To examine position-dependent (semireclined to standing) and walking speed-dependent soleus H-reflex modulation after motor incomplete spinal cord injury (SCI). Participants: Twenty-six patients with motor incomplete SCI (mean: 45 ± 15 years) and 16 noninjured people (mean: 38 ± 14 years). Methods: Soleus H-reflexes were evoked by tibial nerve stimulation. Patients were tested in semireclined and standing positions (experiment 1) and in midstance and midswing positions (experiment 2).Results: H-reflexes were significantly greater after SCI in all positions compared with noninjured people (P , 0.05). Position-dependent modulation from semireclined to standing (normally observed in noninjured people) was absent after SCI. In SCI patients, H-reflex modulation was not significantly different at 1.2 m/s compared with 0.6 m/s treadmill walking speed; in noninjured people, H-reflex modulation was significantly greater at 1.2 m/s compared with 0.6 m/s treadmill walking speed. There was a significant positive correlation between modified Ashworth scores, a clinical measure of spasticity and soleus H-reflex amplitudes tested in all positions. A significant negative correlation was also found between H-reflexes in standing and midstance positions and the amount of assistance patients required to walk. Conclusions: An improvement in position-dependent and walking speed-dependent reflex modulation after SCI may indicate functional recovery. Future studies will use H-reflex testing to track changes as a result of therapeutic interventions.

Influences of H and Medium Latency Reflex Responses of the Soleus Muscle while Receiving with Malleolus Vibration during Upright Standing

“…As a reason for increase of H-reflexes during standing, supraspinal centers might hardly modulate the H-reflexes and MLR during static standing, and the stance and swing phases during walking in those patients 18,[48][49][50] . Nardone et al 50) has shown that Achilles' tendon vibration increases the SLR and MLR activities of Sol of hemiparetic patients with spastic hypertonia due to a loss of descending control from supraspinal centers on group Ia and II reflex pathways.…”

“…In patients with spastic or spinal cord injury that have standing balance impairment and gait disturbance, the Sol H-reflex is increased compared to healthy subjects 19,48,49) . As a reason for increase of H-reflexes during standing, supraspinal centers might hardly modulate the H-reflexes and MLR during static standing, and the stance and swing phases during walking in those patients 18,[48][49][50] .…”

Comparison of Soleus H-Reflexes in Two Groups of Individuals With Motor Incomplete Spinal Cord Injury Walking With and Without a Walker

“…4 Because walkers are routinely prescribed to assist with locomotion in the SCI population, it is important to understand the neurophysiological impact of walker use. The first step in developing a deeper understanding is to assess the reflexes of individuals with SCI walking with and without a walker.…”

“…3 Modulation of soleus H-reflexes is highly task specific; there is smaller reflex size during standing compared to the semi-reclined position. 4 Similarly, the reflex size is significantly smaller (or absent) during the swing phase compared to the stance phase of walking in non-injured individuals. 4 Although the H-reflex modulation is impaired after SCI, it is not clear what specific aspects of standing and walking such as afferent activation and loading during use of assistive devices most directly affect reflex modulation.…”

Impact of Seasonal Variations on Spasticity Assessment and Treatment

“…Craven and Morris (2010) found the intra-rater reliability for the MAS to be fair-to-perfect (0.20<k<1.0), and inter-rater reliability was found to be poor-to-moderate (k<0.60) [12][13][14] . Although measures of reliability are low, there is evidence to suggest that a change in MAS scores indicates a change in muscle spindle excitability [15] and level of excitation at the spinal cord neurons [16] . MAS remains the primary choice for clinicians to measure spasticity.…”