What is central sensitisation?
I personally hate the term central sensitisation. Within the medical system, we know that for some people neurons (nerve cells) in the spinal cord and brain fire sensitising chemicals more easily. This can mean that our central nervous systems can end up in state of increased reactivity (called central sensitisation). Practitioners with a bit more knowledge may also know that within neurons of the brain and spinal cord of people with chronic pain there is an increase in the quantity and activity of a type of a neuropeptide (think messenger protein) called Substance P. Neuropeptides have an effect upon how the brain will respond to sensory information from the body, and thus whether the brain will elicit a pain response.
Why are there limited treatment options traditionally offered?
Unfortunately there is no sector in the medical system at present that dives into why your brain and nervous system respond in this way or what the contributing factors leading to this mechanism are. Subsequently the consensus is you have central sensitisation and we don’t know why your body has reacted this way. So the hope is that with regular exercise and perhaps a pain management course you might feel a bit better temporarily, and at least be able to manage the symptoms for now.
This, while well meaning, often leaves individuals feeling either like something must be being missed, or with the underlying feeling that their body has betrayed them and therefore alone and frustrated.
A rehash on 'central sensitisation'
How I like to think about ‘central sensitisation; which is hopefully a bit less depressing, is that it is simply a phrase coined to describe a temporary increase in danger signalling. Because this is essentially what is happening. But why does this happen in some individuals and not others? It comes down to how your subconscious brain regions and autonomic nervous system have been conditioned to react to stressors throughout your life.
The underlying factors
You see, chemical activity within the CENTRAL nervous system or CNS (where the pain associated neuropeptide called substance P is found) is largely influenced by how much threat our primitive and limbic regions of our subconscious brain detects at any one time. Our central nervous system/CNS includes all regions of the brain and nerve cells that carry signals for sensory information as well as all of the stored memories, meanings, beliefs and emotional associations. Much of our brain is consists of very primitive regions. In fact approximately 95% of our brain runs on subconscious patterns of reaction. So the vast majority of all brain generated signalling (thoughts, meanings, reactions, behaviours) is automatic and derived from neuronal signalling patterns patterns that our brain has already created/encountered before.
This threat detection system is influenced by and has output to another part of the nervous system called the autonomic nervous system (ANS). The ANS is made up of nerves that innervate our muscles and organs and respond to the primitive brain’s commands, and more pertinently, contains fibres that send ‘body messages’ of danger back up to the brain.
How this all works in a nutshell
Every time the subconscious survival brain regions of the CNS detect any sort of threat, such as certain emotions arising, or a social rejection, or a rejection of ourselves, or anytime we my feel helpless or not good enough, we get a release of neurochemicals in preparation to be able to survive. This occurs predominantly within the emotional and primitive regions of the brain and triggers the autonomic nervous system into fight/flight/freeze. Chemicals are automatically activated from the vagus nerve (part of the ANS) into the brainstem, and these chemicals then trigger other parts of the brain to activate to tell the brain 'we might not be ok, stay alert'. And so we think and feel accordingly.
Your limbic and survival brain areas release chemicals to the brainstem where sensory information from the body is incoming which starts to change the perception of sensory signalling incoming.
The final result
The more this occurs and the more we flood our brain and central nervous system with neurochemicals, the more excitatory our central nervous system becomes. Thus it is 'centrally sensitised'. So now we have all of this incoming sensory information from the body that is not only being delivered to the brain in a more excitatory/increased sensory way, but we also have regions of the brain that are involved in detecting how to respond to sensory input that are now more active. So then we start to feel pain. But as you can see, it is not because our body is damaged.
What drives this protective mechanism to persist?
When our subconscious brain regions and ANS continue to respond to potential threat, it is usually because:
a. The underlying emotional and psychological factors that are driving the increase in neuropeptide signalling stay the same.
b. The brain is used to generating the same neuronal firing patterns as it has done previously. Your brain just wants to do the same thing it did the day before because that 95% that is subconscious only cares about you surviving, not about your happiness. Our brain learns to anticipate how to respond to sensory information based on what it already knows. This is called predictive coding and I will talk about this phenomena more in a separate post. But this is good news because changing this can be relatively simple.
So I hope that helps clear up 'central sensitisation' for you. The good news is just as your brain and nervous system has become more sensitised, they can also become less sensitised. And the key to this is cultivating safety within these subconscious regions of the brain and through the body.
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