In the lead up to MS Awareness Month in May, I shall tackle a question that we always get asked – how should we approach the walking problem in MS?.
I have to say, the most frustrating thing I hear from people with MS is they never really know what they need to do to help their walking when part of their body fails them.
Sounding familiar? Feeling disempowered?
Today, I will answer one of my most frequently asked questions on this subject:
Q: How am I supposed to strengthen a muscle I need for walking that I cannot even use?
A: First, we must be careful when using the term “strengthen” because it implies that the muscle can normally activate but it is just weak. Now this may be the case in MS, as a seconday effect, however it is more probable that there is a problem with the nervous system carrying enough signals to the muscles in order to create a visible contraction. Therefore it is more about gaining active movement control first, rather than just strengthening.
All muscles, during voluntary use, need electrical activity driven from the brain, through the spinal cord to the minimally excitable threshold at the neuromuscular junction, which is the last connection of the peripheral nerve fibres to the muscles themselves.
In MS, where there are lesions to the brain or spinal cord, the sensory and/or motor fibres are be damaged and so few signals are getting to the muscles and the skin, and at a slower rate. This is like when you have a 4 lane highway bottle necking into a 1 lane street. Everything is slower and harder to get through.
So in order to achieve the intended effect of muscles reaching threshold, we have to try and create more pathways for signals to go through, and we could do this by using a variety of methods.
One possible method of creating muscle activation is using functional electrical stimulation, so as to create a “higher up” (corticospinal) response and guide the brain and spinal cord to “find its way” again or open up a collateral channel that the brain can learn from.
The applicability of this type of therapy can be difficult to reproduce consistently because there are many factors that influence its effect. These include:
- skin conductance
- thickness and quality of skin
- quality of underlying tissue/fat/swelling
- temperature of muscles
- size of muscles
- size and frequency of current
- size and position of electrodes
- type of muscle
Nonetheless, it is a useful modality once muscles can be stimulated because you can produce a learning effect due to the sensory surface stimulation as well as the internal stimulation to the muscle spindles that detect motion within those muscles.
Both these stimuli can help your brain and spinal cord learn to activate muscles themselves over time.
Another method is to create the right input into the muscle, skin and joints to mimic the activity of the muscle, as another way of helping the brain and spinal cord “find its way”. We can use a combination of compression, mobilisation and sometimes reflexive techniques to help it along. Here, repetition, specificity and reducing error for learning are most critical.
It is much harder to do right, and is highly dependent on therapist skill, but can often reap faster rewards.
From here, we help manipulate the task to make it easier or harder, and how gravity might work with or against it. We can also change the speed and timing of the contraction to give the brain more information to learn from. It’s like practising drills that have variety to improve skill and applicability in real life.
Other things that I also consider in my approach:
- Rather than look at a muscle in isolation, look for another supporting muscle or group of muscles that can help the most paralysed muscle get a kick start. For instance, getting toes to lift can help some muscles bend the ankle upwards to help the foot clear the ground. And sometimes these groups of muscles are nowhere close to each other.
- Don’t under-estimate the power of demonstration. Often showing how the body part should move will help create a better sense of how the movement should occur, and allow the brain to see patterns, even if it is not immediately conscious to the patient.
- On the flipside, consider the need to use vision, and when it may be better to obscure it. Some movements require proprioception, and that also needs specific training.
And the rest they say, is therapy.