Friday’s second session was presented by Susan Harkema. It didn’t really have a name, so I’m calling it what the presenter said was the point of the lecture: Increasing the Central State of Excitability
Now what does that mean? A lot in the spinal cord injury population! Susan discussed the use of body weight supported treadmill training (BWSTT) in SCI– what it does and why we should be doing it and also the use of spinal cord stimulation. BWSTT and spinal cord stimulation fall into activity based therapy category of treatment, meaning a therapeutic treatment tool that mimics an everyday activity. Research has been supporting these types of treatments over traditional therapeutic exercise, because they tap in “activity-dependent plasticity”, is “salient” to the patient, and very repeptitive. Getting some big words there. Activity-dependent plasticity is like specificity of training– if you want to be able to dribble a basketball well, you practice dribbling… if you want to walk well, you practice walking. Walking improvement is also a common goal for patients; therefore it is important which is a simpler word for salient. Repetitions are important in neuro rehab too. The more times you practice doing an activity correctly, the more likely you’ll do the same activity correctly in real life. In SCI there are two types of activity-dependent plasticity driving treatments: task specific training (learning and practicing compensatory strategies of movement, such as para-transfers, wheelchair mobility, etc.) and neuromuscular activation below the level of injury (restorative techniques including BWSTT and spinal cord stimulation.)
In body weight supported treadmill training, you take a patient, strap them into a harness and dangle them over a treadmill. Then several people help them move their legs in a walking pattern while the treadmill moves. Like this (video starts at 0:13.)
The BWSTT acts to “increase the central state of excitability” in the spinal cord. This whole treatment is based on the assumption that direct control of the brain is not necessary to retrain basic movement synergies as the spinal cord is “smart.” We used to say that the spinal cord housed central pattern generators (CPGs) and that’s where the movement came from, but that term has fallen out of use.
I’ve seen several protocols. Total session times range from 30-90 mins x 60-80 sessions. Each bout of training lasts from 3-5 minutes, as the patient tolerates and progresses. Treadmill speeds begin at 1.0 mph and increase up to 2-3 mph. The body weight support starts at 30% and decreases down to 0%. The body weight support is the last variable you change, meaning that you want to bump up the intensity in the other 2 variables (bout time and speed) before increasing intensity with less body weight support. This requires 2-3 trained staff to perform and from experience, requires some endurance on the part of the staff as well.
The trouble I’ve found with this treatment is 1) the harness is terribly uncomfortable as it lifts you from pressure points at the ASIS (top of pelvis) and also the pubis (bottom of pelvis), 2) getting the patients onto the treadmill. Most treadmills are slightly elevated, so the patient must be able to navigate a fairly sizable step and then stand well enough to have the harness applied, 3) we (at least in the places I’ve been) are being pushed to use this treatment method on patients that cannot do the items in 2, who are perhaps not the population this treatment was designed for 4) you need a lot of staff to do this with and it is not charged any differently than traditional over land gait training, so we don’t get reimbursed for the extra staff needed to do the treatment and 5) the equipment is a large financial investment. I don’t use it much personally, but I’m hearing about it more and more and went to a brief training on it, so perhaps I will be using it more in the future.
Susan has been combining BWSTT with epidural stimulation. The first patient (ASIA B)they had with epidural stimulation’s goal was just to stand, so that’s what they were working on at first. Then 7 months in, the patient said, “Look what I can do!” and moved a leg voluntarily, so they moved on to gait goals with BWSTT. That voluntary part is what makes the epidural stimulation so spectacular. ASIA B’s are not supposed to move, so by using the stim to restore movement that the patient can control on their own is a big deal. Add the BWSTT on top of epidural stimulation, and the patients can be trained to move in functional, daily life patterns of walking. Woah. Other “off the shelf” gains include improvements in bowel, bladder and sexual function. I also suspect chronic neuropathic pain may be improved as well, based on what others are saying, but Susan didn’t mention that. Susan hypothesizes once again that this is all possible by increasing the central nervous system’s state of excitability, meaning making it more susceptible to doing what the patient tells it to do.
So now I’ve got you all excited about BWSTT right? I have no connection with them, except I took their NCS prep course, but NeuroRecovery Training Institute has a series on BWSTT, so you can learn how to do it better than I know how. Click the link if you want more info on that.
Epidural stim requires surgical placement of the stimulator on top of the spinal cord, so is beyond the therapists’ scope of practice to initiate. So you may want to call around in your area and see if any of the neurosurgeons or maybe the back surgeons are doing these. It will also require the stimulating equipment, which I honestly have no idea how to get a hold of that.
So that was session two!