Is it all in my head? Pain neuroscience in a nutshell

If you’ve been in pain a long time, you’re not alone. One in five Australians aged 45 or over (or 1.6 million people) live with chronic pain, according to figures from the Australian Institute of Health and Welfare. A pain specialist knows chronic pain can adversely impact your life in many ways. Aside from the frustration and discomfort, people with chronic pain are five times more likely as those without pain to experience significant limitations with everyday activities. 

To understand how a pain management specialist – like those at Brisbane Private Hospital’s Pain Medicine Services – help people living with chronic pain, it’s helpful to know a bit more about how pain is experienced. 

Understanding pain – nociception vs pain  

“Identifying the difference between pain and nociception early on may reduce potential harm and management delay.”

A person referred to a pain specialist for chronic pain management has typically had pain in more than one area (like neck pain and headaches) for periods ranging from months to years. They may have had various diagnoses by their GP and seen relevant specialists. They have often tried different medications, which were not effective enough or caused unacceptable side effects. 

Some have had surgeries to ‘fix’ the issue, which unfortunately only had short term benefit. People with chronic pain often say that they have ‘tried everything – but nothing works’. 

This impacts a person’s function, along with their physical and psychological wellbeing. 

Identifying the difference between pain and nociception early on may reduce potential harm and management delay.  

What is nociception? 

Nociception is the scientific term used to describe what happens when your body perceives actual or potential harm. When we hurt ourselves (by putting our hand on a hotplate, for example), the perception of harm activates certain chemicals and channels. This signal travels to the brain via a complex series of nerves, including the spinal cord.

What is pain? 

On receiving this signal, the brain processes it and generates a response or message. If this message is to get to safety (in the above example, by taking your hand off the hotplate), it will register as pain. If an outcome is not considered dangerous, then there is no pain.  

How do we perceive pain? 

“Even when harm signals are being triggered, our brain doesn’t always express pain.”

The important thing to note is that nociception is not equal to pain. Even when harm signals (or nociceptive signals) are being triggered, our brain doesn’t always express pain. For example, you may have seen a player finish a big game, not realising they have a fracture.

Conversely, you can also experience pain when no actual harm is occurring, as is often the case in chronic pain (more about this below).
Pain is a signal of danger. That danger is something perceived by the brain. This perception can come from sensations within our body (interoception) or from our external environment (exteroception). 

“The brain areas receiving nociceptive (harm) signals also deal with memory, emotions, logical thinking, and fear/worry.”

A harm signal generated from a body part travels through the nervous system, then the spinal cord and brain give context to this signal. If the context is perceived as dangerous, it is expressed as pain. This makes us seek safety. We may do this in multiple ways, such as retreating from a situation or doing something to resolve the danger and feelings of anxiety, like taking medication. 

Significantly, the brain areas receiving nociceptive (harm) signals also deal with memory, emotions, logical thinking, and fear/worry. This means harm signals can get bound up in the brain with feelings, thoughts and memories, which helps explain why chronic pain can get worse under certain circumstances – such as when you’re tired, unwell or stressed.  

The common belief that pain and nociception are one and the same is incorrect. Nociception responds well to treatments like drugs and interventions/surgeries. Pain requires more comprehensive assessment and targeted management.

Chronic/persistent pain 

If pain lasts longer than the expected injury/surgery healing time (or more than 12 weeks), it is classified as chronic pain or persistent pain. In chronic pain, there is often no suggestion of an active nociception.   

There are two main subtypes of chronic pain: 

• Neuropathic – where there is proven nerve damage, and
• Nociplastic – which involves inflammation in the immune system of the brain and spinal cord.

Central sensitisation 

“We don’t have to have a cut, surgery, fall or injury to feel pain. This is called central sensitisation.”

Because pain is a danger signal that can come from within the body or our external environment, it isn’t always associated with actual bodily damage. We don’t have to have a cut, surgery, fall or injury to feel pain. This is called central sensitisation.  

Central sensitisation involves changes to the way the central nervous system processes sensory information. Have you ever stayed in a hotel where the fire alarm is wired to go off even at a whiff of burnt toast? Central sensitisation is a bit like this. Changes in nervous system wiring mean signals that would not typically lead to pain, such as pressure or movement, trigger a danger warning.

If you had an accident that led to chronic back pain, for example, simply driving past the accident site can trigger another pain episode.

Several disorders that involve chronic pain (including fibromyalgia, irritable bowel syndrome, chronic headache, temporomandibular disorders, and pelvic pain syndromes) appear to overlap and share common features, although their primary body locations differ.

Historically, these disorders have been isolated from each other, with treatment involving help from a specialist with expertise in that body area (such as a gastroenterologist, neurologist, or dentist).

Over the past decade, however, there has been growing recognition of the significant overlap between these disorders where persistent pain is a predominant feature – along with other symptoms such as fatigue, sleep problems, dizziness, cognitive problems, depression and anxiety. 

It is increasingly recognised these disorders may share an underlying mechanism. As a group, they have come to be known as ‘central sensitivity syndromes’.   

What does this mean for chronic pain management?

“Attempting to cure pain without understanding its complexity is always going to be a hopeless exercise.”

Most importantly, this understanding provides pearls of wisdom we can apply in the pain management clinic.

1. Treatment strategies that target local areas (that is, within the painful anatomical region – such as local massage for back pain) are typically of little value for people with predominant central sensitisation pain. A more ‘central’ approach, targeting brain and top-down mechanisms, seems more warranted for treating this type of pain. This applies to conservative as well as drug-based treatments. 
2. People with severe and spreading pain, as typically seen in central sensitisation, often reflect on their pain (and why they do not respond to local treatments). Therefore, the first step in treating central sensitisation often requires education and explanation of pain – that is, pain neuroscience education. This allows people to better understand their condition and develop more helpful pain beliefs and coping strategies.
3. After the initial educational treatment phase, active interventions such as stress management, sleep management, graded activity/graded exercise therapy, and graded exposure may benefit patients with predominant central sensitisation pain. 
4. Finally, given the fundamental role of cognitive-emotional factors (e.g. pain catastrophizing, anxiety, varying pain beliefs and coping strategies, anger, perceived injustice) in sustaining central sensitisation in patients with chronic pain, a comprehensive treatment plan should target those factors. 

Attempting to cure pain without understanding its complexity is always going to be a hopeless exercise. Developing a pain-free mindset may be the best way forward for long term pain control. 

It is not a quick-fix and is far from being easy. However, it is the most evidence based, scientifically proven, successful way to take back control of your life, find purpose and meaning and get back to doing things that you love.

 

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