Soleus H-reflex modulation after motor incomplete spinal cord injury: effects of body position and walking speed.
OBJECTIVE
To examine position-dependent (semireclined to standing) and walking speed-dependent soleus H-reflex modulation after motor incomplete spinal cord injury (SCI).


METHODS
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.
Rehab Science Program, University of Florida, Gainesville, 32610-0154, USA.
Chetan P
CP
Phadke
Floyd J
FJ
Thompson
Carl G
CG
Kukulka
Preeti M
PM
Nair
Mark G
MG
Bowden
Sangeetha
S
Madhavan
Mark H
MH
Trimble
Andrea L
AL
Behrman
D000293:Adolescent; D000328:Adult; D000368:Aged; D005080:Exercise Test; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D013119:Spinal Cord Injuries / Q000473:pathology* / Q000503:physiopathology; D018709:Statistics, Nonparametric; D016138:Walking / Q000502:physiology*; D055815:Young Adult