Our
original CPG studies (described here) led to a clinical trial of rehabilitation
methods for improving walking after SCI.
The question was: if the spinal cord was capable of producing stepping
movements of the legs, could this central pattern generator be trained to improve walking in persons whose
walking ability was limited due to SCI?
We enrolled
subjects with neurologically-incomplete injury. This means that they retained,
or had recovered, the ability to contract some muscles in one or both legs
after their injury. However, most
were still dependent on their wheelchairs as their main form of mobility. Also,
all subjects had chronic SCI, meaning they had been hurt at least one year prior to starting the
study. We knew that there can be
considerable spontaneous recovery of function during the first year after injury, and wanted
to avoid mistaking any spontaneous improvement in walking with improvements due
to the training subjects performed as part of this study.
In this
randomized clinical trial, subjects were assigned to one of 3 groups. Two groups used a form of body-weight
support (BWS) training. A harness
was fit to each subject, and some of his or her weight was lifted up through
the harness via an overhead cable.
One BWS group trained over a moving treadmill (BWS/treadmill); the other
BWS group trained over fixed ground, by walking under an overhead monorail
track with a roller lift mechanism (BWS/track). The third group received comprehensive physical therapy
(PT).
To mimic a
typical therapy schedule, we had all subjects train for no more than 1
hour/day, 3 days/week, for a total of 13 weeks.
We found
that – on average – subjects in all 3 groups were able to achieve significant
gains in both walking speed and leg strength. Moreover, subjects in the BWS/track and PT groups showed
significant gains in balance. About
20% of the subjects in our study were able to retire their wheelchairs as their
primary form of mobility, and just walk …. pretty cool stuff. Our paper describing these findings can be found here.
We didn’t
find that one form of training was any better than another in improving
walking, nor did we find any evidence that our study resulted in training of a person’s CPG for walking.
So why did
walking improve?
Most
subjects had stronger legs after training. Many subjects had better balance after training. And many subjects had improved stamina,
or the ability to exercise at relatively high intensity, after training. It should come as no surprise that –
with these training-specific changes in function – our subject’s walking
ability improved, too.
Yes, we were disappointed about the absence of any
obvious CPG training effect. But
the really important finding from this study was that many persons with
chronic, incomplete SCI have an ‘untapped’ ability to improve their strength
and walking function, if given the opportunity. The really difficult part will be when they have to convince
their insurance company, or Medicaid, that they deserve that chance. Our findings from this study should
help appropriate persons with SCI make just this argument.
