Can anti-spastic medication facilitate robotic-locomotor training?

We aimed to determine whether an anti-spasticity medication (tizanidine) can facilitate the effects of robotic locomotor treadmill training (LTT) to improve gait function. Individuals with incomplete spinal cord injury (SCI) were recruited and carried out a 4-week intervention of either locomotor treadmill training (LTT) alone (n = 26) or LTT combined with tizanidine (TizLTT) (n = 22). Gait function was evaluated using clinical outcome measures of gait speed, endurance, and mobility. We used two-way mixed design analysis of variance to assess changes over recovery time and due to interventions. We defined the amount of change for the improvement to be considered “clinically” meaningful as the minimal important difference (MID) for clinical scores. Group-averaging analysis indicated that both LTT and TizLTT resulted in significant improvements in walking speed, with no significant differences between them. However, using the MID analysis, a higher proportion of subjects in the TizLTT group achieved the MID for walking speed (40%) compared with LTT alone (13%). Those that achieved the MID for walking speed were significantly higher functioning at baseline than those that did not in the TizLTT group. We concluded that tizanidine can facilitate the effects of LTT on gait function in individuals with SCI that are higher functioning at baseline. This may be due to restoration of inhibitory mechanisms by tizanidine, resulting in greater stretch in the planterflexors during the LTT.