Previously we discussed structural differences in the properties of healthy and spastic/rigid muscles and connective tissues. After concluding that those differences are present, we further explained that the affected muscles and connective tissues will mechanically respond differently from the healthy structures when passive stretching is applied to them. Accordingly, the end results of tissue adaptation to passive stretching will also be different between those two groups of tissues.
But why do connective tissues and muscles in cerebral palsy person mechanically respond differently to the same procedure?
Our observations are that, except for the obvious brain damage, a child with cerebral palsy experiences the structural collapse[1]. During the assessments of children’s condition, we clearly see the structural collapse of the connective tissue. There is a connection between brain damage and the collapse/damage of the connective tissues and that connection will be explained in the next article.
In essence, in the process of weakening, connective tissues lose the ability to retain water. The extracellular matrix that normally should be fluid starts to change and hardens which increases the stiffness of the soft tissues. Accordingly, we can observe that connective tissues lose their volume (in all three spatial dimensions). Further, as we showed in the previous article there is also an accumulation of collagen fibres and consequent thickening of connective tissues, which makes them less elastic, stiffer and less organized. Negative changes are present in the muscle tissue, too. There is a reduction in contractile muscle fibres.
On the basis of the above listed, it is clear how weak and qualitatively distorted connective and muscle tissues are different from the healthy ones. This is the reason why their mechanical response to passive stretching will be different, as shown in the scientific research cited in the previous article.
The next question should be: why should we be cautious about the application of passive stretching to those weak and distorted soft tissues?
Brain damage induces systemic inflammatory processes that accumulate and increase from the moment of the brain injury onwards. Practically, it means that pro-inflammatory[2] substances are present in higher levels than normal in people with brain injury. Further, it means that not only the central and peripheral nervous systems (CNS and PNS), but also all bodily tissues are affected with inflammation.
It needs to be pointed out that in normal circumstances, inflammatory processes have a positive role because they help the body to heal and restore balance. An inflammatory process should do its workings, help the body to heal and then cease. Unfortunately, in the case of brain injury, it seems that it has a detrimental effect because it is excessive and long-lasting. It looks as if it doesn’t stop when it should, but instead, continues as silent inflammation. People with brain injury are constantly under the high level of inflammation; higher than in healthy people. That makes them very sensitive to different kinds of mechanical influences. The point is that inappropriate levels of long-term inflammation damage the tissues even more. In other words, it is a healing process that went wrong and instead of healing, it induces the forming of densifications, adhesions, fibrosis, and scarring of the connective tissues.
- Densification (thickening) of connective tissues occurs as a result of the distortion of myofascial relationships, reducing sliding facilities and altering the muscle balance and proprioception (Stecco & Stecco 2009).
- Adhesion refers to the tendency of the fascial layers to stick to one another which in the long run reduces sliding and gliding properties of fascia. ‘When fascia is excessively mechanically stressed, inflamed or immobile, collagen and matrix deposition becomes disorganized resulting in fibrosis and adhesions’ (Langevin 2008).
- ‘Fibrosis is defined by the overgrowth, hardening, and/or scarring of various tissues and is attributed to the excess deposition of extracellular matrix components including collagen. Fibrosis is the end result of chronic inflammatory reactions induced by a variety of stimuli, including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury’ (Wynn T.A. 2008).
Why is this a problem, in the context of passive stretching? In the case of people with an injury of the CNS and/or PNS, the changes in connective tissues such as densifications, adhesions and fibrosis are already present together with the high levels of inflammation.
Scientific findings show that different types of precise mechanical stimulation can modulate inflammation either toward healing or toward further damage and fibrosis. Whether it is going to promote inflammation or decrease it, depends on the kind of mechanical stimuli we use.(Guoguang Yanga, Hee-Jeong Imb, and James H.-C. Wanga,* 2005) In the study from 2005, researchers wanted to know if stretching of the tendon will change the level of the inflammation in it. They made four different situations.
- The tendon wasn’t induced with pro-inflammatory substance and wasn’t stretched. Inflammation expectedly didn’t occur.
- The tendon was induced with pro-inflammatory substance but wasn’t stretched. Inflammation increased in relation to situation 1 even though the tendon wasn’t stretched but it was lower than in situation 3.
- The tendon was induced with pro-inflammatory substance and was stretched 8% of total tendon length. Inflammation increased and was higher than in situation 1 and situation 2.
- The tendon was induced with pro-inflammatory substance and was stretched 4% of total tendon length. Inflammation reduced in comparison to situation 2 and especially 3.
If we put it in simple words, when the tendon was already inflamed and stretched 8% of its length, inflammation got worse. When already inflamed tendon was stretched 4% of its length, inflammation significantly reduced. When non-inflamed tissue wasn’t stretched, expectedly, there was no inflammation.
Let’s observe the situation: we already noted a high presence of inflammation and damage in the people with an injury of the CNS and PNS. If we apply passive stretching on damaged, inflamed and oversensitive connective tissue, what is the chance that we will be so precise in our application, that we are certain of inducing a positive healing process instead of the negative damaging process?
We need to be aware that the effects described in the research are produced in a well-controlled laboratory environment and with the usage of measuring instruments. Are we sure that we can have such a controlled environment at home? I doubt that.
From this, we can conclude that passive stretching, in the long run, is very likely to cause irritation and increase inflammation in the connective tissues and consequently promote the processes of densification, adhesion, fibrosis, and scarring rather than the healing process.
My idea is not to leave parents without options on how to deal with spasticity and contractures. From everything explained, I believe that passive stretching is not reliable enough so that parents can achieve desirable results.
There are other, safer ways. There are modalities of repetitive low-magnitude and low-intensity mechanical loading which are safe and act in such a way to promote tissue reparation and healing processes.My question is: why hold on so blindly to passive stretching if you can achieve better long term results with BDA techniques and even other soft tissue techniques?
In the next article, I will write about soft tissue remodelling and BDA techniques which can be used to reduce stiffness, increase mobility and deal with the contractures in the long run.
[1] Structural collapse implies the weakness of all types of connective tissues regardless of their type and localization in the body. Also, it points out to the loss of their architectural role, as tissues which should give internal pressure, support and hold the human body from the inside. When connective tissues are weak and can’t perform this role anymore — that is structural collapse.
[2] Substances that promote inflammatory processes in the human body. When we experience traumatic injury or foreign organism attacks (bacteria, viruses, fungi, parasites), our body activates the immune system response. The goal of the immune system response is to start the inflammation processes which in the end will result in healing and restoring general balance in the organism.
