What is Central Sensitization?

If you have pain or other symptoms that have persisted for a long time or have spread across your body, you might have come across the term central sensitization. But what does it mean, and how does it relate to your experience of pain?

Central sensitization is a key mechanism in many chronic pain syndromes and is sometimes formally recognized as central sensitization syndrome (CSS) or pain system hypersensitivity. In this article, we’ll explore what central sensitization is, how it develops, and how it can be managed.

Before you dive in, we want to remind you that your pain is real and no-one can tell you whether you do or do not have it. It's not “all in your head.”

Pain is complex and multifactorial, and is different for everyone. 

What is central sensitization? 

Central sensitization (CS) is a condition where the central nervous system (CNS) – that’s your brain and spinal cord – becomes overly sensitive and reactive to stimuli that typically would not cause pain.

To break it down:

• Central refers to the CNS, which includes the brain and spinal cord. But (just to make it extra confusing!), it’s not just the nervous system – your endocrine (hormone) and immune systems can also get involved, creating inflammation and stress responses that further heighten pain sensitivity.
• Sensitization describes the gradual change where the CNS shifts into a high-alert, overprotective state and begins to misinterpret normal, safe signals as potential threats, triggering intense pain or discomfort¹.

Pretty much anything can be a stimulus. A gentle touch, or a hard hit. Chemical substances, light, sound, smells, cold, heat, the weather and electricity. Even thoughts and feelings and stress.

This process can lead to chronic, widespread pain that doesn’t seem to correlate with any specific injury or inflammation. The body hurts, even when there is no harm.

The nervous system essentially becomes stuck in a “pain mode,” amplifying normal sensory inputs. Imagine you have a hearing aid and it gets stuck on level 8, everyone continues talking at their normal levels, yet all you hear is shouting! It’s like that, but for pain.

How does central sensitization affect pain?

This is complex and can be confusing. 

So, for the sake of simplicity, let’s consider your body as a collection of complex and interacting systems, with the central nervous system as the key player. These systems are influenced by a range of inputs and outputs.

Pain is an output of the CNS and serves to protect us from harm. For example:

1. Nerves in the body detect a noxious (harmful, poisonous, or very unpleasant) stimulus. For example, a very high or low temperature, certain dangerous chemicals, or intense mechanical pressure such as stretching or compression.
2. The nerves transfer this information to the CNS as a danger message. “Hey brain, this might be bad, what do you want us to do about it?”
3. The brain then processes this information, taking into account many other complex factors, including past experiences, emotional and cognitive inputs. It decides if protection (pain) is required. And it will usually err on the side of safety – better to be safe than sorry!

Over time, the CNS can become deregulated, out of balance or sensitized. The way the system is designed to function somehow goes awry and starts making errors, overamplifying “safe” sensations as dangerous.

As a result, many normal, non-threatening stimuli, like basic movements, can be amplified and result in increasing pain and discomfort. And, because all of our bodily systems interact, it can compound the dysregulation even further. So much so that the output of pain can in itself become a cause of dysregulation and stress, and yes, more pain.

Causes of central sensitization

Central sensitization can develop for many reasons, often related to when our body systems become dysregulated. The most common include:

• Genetics: If you have a parent with CS, you are eight times more likely to develop widespread pain than the average population².
• Hormonal abnormality: When other systems become dysregulated such as in neuroinflammation and hypothalamic-pituitary-adrenal (HPA) axis dysregulation.
• Illness or injury: While initial healing occurs, processes such as inflammation and nociception become sensitized. 
• Other conditions: Central sensitization is commonly associated with conditions like fibromyalgia, chronic fatigue syndrome (CFS/ME), irritable bowel syndrome (IBS), migraines, and other chronic pain syndromes.
• Inflammation and stress: Chronic inflammation and prolonged stress, especially following trauma, can play significant roles in the onset of central sensitization.

Symptoms of central sensitization

The symptoms of central sensitization can be varied, but they generally include:

• Widespread pain: Pain that affects multiple areas of the body without a clear cause. Pain often persists well beyond normal healing times for injury or illness. 
• Sensitivity to stimuli: Increased sensitivity to touch or pressure, temperature, and even light or sound. This can manifest as allodynia (pain from stimuli that don’t normally cause pain) and hyperalgesia (exaggerated pain response to painful stimuli).
• Magnification: Central sensitization often leads to pain that may spread to other areas of the body, and can also result in fatigue due to lack of quality sleep, abdominal pain, poor cognitive function (or “brain fog”), depression or anxiety, and headaches.

Diagnosing central sensitization

Diagnosing central sensitization can be challenging because there’s no specific test for it. However, certain patterns and symptoms can indicate its presence. One helpful tool is the Central Sensitization Inventory (CSI), a questionnaire designed to identify symptoms associated with central sensitization³.

The CSI prompts people to consider how much they experience different physical, emotional, and cognitive symptoms that are commonly linked to central sensitization, and whether they have any diagnosed conditions that are associated with central sensitization. These include symptoms and conditions such as:

• widespread pain
• fatigue and sleep disturbances
• concentration and memory problems
• mood disturbances, such as anxiety or depression
• sensitivity to touch, noise, light, and temperature
• other symptoms, such as headaches, gastrointestinal issues, and dizziness
• conditions like fibromyalgia, irritable bowel syndrome.

It’s also important to rule out other possible conditions and identify any red flags that could indicate specific structural or pathological damage.

You can also take an online quiz to help determine if central sensitization might be playing a role in your pain.

Conditions where central sensitization likely plays a role

Central sensitization can often play a role in other chronic pain conditions⁴, amplifying symptoms and interacting with other factors that cause the issue. These conditions can include:

• Fibromyalgia
• Rheumatoid arthritis
• Irritable Bowel Syndrome (IBS)
• Chronic headaches and migraines
• Endometriosis and pelvic pain
• Chronic musculoskeletal pain
• Temporomandibular joint disorder

These conditions often involve complex interactions between the nervous system and other body systems, including the immune and endocrine systems. Understanding the role of central sensitization in these conditions can help guide effective treatment strategies.

How to treat central sensitization

Managing central sensitization involves focusing on calming the dysregulated nervous system. Some key approaches include:

• Pain education: Understanding the mechanisms of CS has been demonstrated as a valuable and effective intervention for chronic pain⁵.
• Somatic tracking (a key component of Pain Reprocessing Therapy): CS is an example of neuroplasticity, where the nervous system has changed and adapted over time. And we can use the same concepts to retrain our nervous system to be less protective! Somatic tracking is one technique that can be used to retrain the brain to perceive stimuli as non-threatening, helping to reduce pain and sensitivity over time.
• Lifestyle factors: Regular exercise, eating a balanced diet, getting enough rest, and practicing good stress-management techniques can all help in managing central sensitization.
• Medical interventions: Some medications can help manage symptoms so that you can engage with the other approaches mentioned above. This of medication as taking the edge of, enabling you to take an active approach to healing.

By gaining a deeper understanding of central sensitization and how it affects your body, you’re taking an important step toward reclaiming control over your health and wellbeing. With the right strategies and support, it’s possible to manage your symptoms and improve your quality of life​​.

More information

Understanding central sensitization is a crucial step in managing chronic pain. Remember, just because there’s pain, doesn’t mean there’s is definitely underlying damage – your nervous system is overprotective.

At MoreGoodDays®, we are committed to walking with you towards a life of greater wellbeing, despite the challenges of living with chronic pain. Download our mobile app for free from the Apple App Store or Google Play Store to get instant access to a selection of our science-backed approaches to transformative chronic pain care, and discover the variety of support options available.