2023-04-17

What is chronic pain?



Pain sucks. Chronic pain sucks even more. And for many stroke survivors, this is now their life. Actress, artist, documentarian, and stroke survivor Maggie Whittum explored the world of chronic pain with us in episode 38 and with Barbie dolls filled with nails or covered in suffocating clay. Other survivors have talked about living with pain, even when there is nothing "wrong" with the limb. 



 
 
 
 
 
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And once you've lived with pain for several months you don't become accustomed to it. In fact, the nervous system increases  your response to pain.

So what's going on here?

The brain damage from stroke drives chronic pain in many survivors through a perfect storm of symptoms:

  1. Decrease in sensory filtering
  2. Increase in sensitivity

  3. Homuncular changes in the mind-body connection

In this conversation, Physiotherapist and pain specialist Brendon Haslam joins us to talk about the nature of post stroke pain, how clinicians may treat it, why some medication work while others don't, and how, after stroke, we may no longer know just how big or small our hand is.

If you don't see the audio player below, visit the original article page here.

 

Who is Brendon Haslam?

Brandon Haslam looks at the camera while wearing a navy blue sweater

Brendon is a physiotherapist and current PhD candidate with the University of Melbourne. Brendon has a particular interest in pain following stroke, and his PhD is focusing on identifying contributions to upper limb pain in stroke, and understanding possible neural networks involved in the pain experience.  The aim of this research is to increase understanding of pain following stroke, and subsequently develop effective interventions to manage the significant problem of chronic pain in stroke.

What is chronic pain?

Once someone experiences a pain for 3 months, it's considered chronic pain.

The nature of chronic pain after stroke goes deeper, though. For one thing, we normally think of pain as resulting from tissue damage or injury. While sometimes joint injury, shoulder subluxation, tendonitis, and other conditions may be a factor, they don't tell the whole story.

For example, lightly touching an affected limb may be extremely painful. Applying the exact same stimulus to and unaffected limb and an affected limb may feel like nothing on one side and extremely painful on the other, even if there is no physical difference in the stimuli.

A stroke affected limb may just hurt for no obvious reason. And that can be what the survivor just has to live with.

Over the last 20-25 years, as Brendon explains, our understanding of pain has evolved quite a bit. We no longer think of it as coming from specific pain receptors. Rather, it a broader sense of safety or danger to the body. And the more someone lives with chronic pain, the more sensitive the nerves at the spine will become to those sensations. Rather than learning to ignore the pain, we can become even more sensitive to it.

One of the biggest challenges with stroke recovery is how the brain sometimes loses the ability to inhibit or disregard signals and data. In the case of chronic pain, the brain fails to disregard those signals as the spinal cord in effect raises the volume.

In the case of tone and spasticity, as we learned from Dr. Wayne Feng, the brain loses the ability to inhibit signals from the spine to the affected limbs that drive tone.

For some survivors, like artist Seth Ian Shearer and NeuroNerd Joe Borges, the stroke reduced the ability of their brains to filter out or inhibit external sensory input. The go out and about with sunglasses and earphones to navigate the world.

Stroke is as much about the brain no longer stopping things as it is about the brain no longer being able to do things. And chronic pain falls right into these challenges.

The Study

I wanted to speak with Brendon after reading a study published in the journal Brain Sciences called “My Hand Is Different”: Altered Body Perception in Stroke Survivors with Chronic Pain.

It's a fascinating look at how stroke survivors with chronic pain develop a false image of the affected hand.

Our results support the hypothesis that individuals with sub-acute and chronic stroke who experience chronic pain are more likely to report changes in body perception (as indicated by presence of alterations in perceived hand size) than those without pain. Further, the frequency of altered body perception of the hand, and strength of the association were greater when the region included the hand.

We've talked about the homunculus in previous episodes, and you can read more about the idea of the homunculus in this Strokecast article. Basically, the homunculus is a representation of the amount of neuronal real estate taken up by different body parts based on how much we use them and how we use them. For example, the thumb will occupy more space in the brain that the elbow.

After stroke, our homunculus can undergo changes based on the injury and our new use patterns for our body. And among those changes are how we feel pain.
 This study provides useful information in understanding that those changes take place. It reinforces the idea that pain is related to homuncular perceptions. And it further supports the perfect storm of chronic pain causes that we discussed in the episode.

Hack of the Week

Brendon's hack is to get into meaningful activities that bring you joy. Sort of like how Tawnie in the previous episode got into Mermaiding.

There are lots of reasons to focus on activities like this -- whether that's volunteering in a community, playing a sport, creating art, developing a podcast or something else. Doing something deliberate and planning it gives us something to look forward to. Having a reason to get out of bed is super important, not only for stroke recovery, but for life in general. Making progress, striving, or even just doing something to improve your life and mood -- to bring joy is a powerful motivator to keep going. And for some folks, that means to just get to the next day. For other folks it's a way to change the world.

Pursuing activities that bring genuine joy is a good thing in and of itself.

But as Brendon points out, it has biological implications, too. It opens the proverbial "drug cabinet" in our brains to drive increased dopamine. This drives learning, which is the essence of stroke recovery -- teaching the brain to do the functions the dead brain cells used to do. Dopamine also drives the production of Gaba. And Gaba works to turn down the body's sensitivity to irrelevant information.

Essentially, it helps the body inhibit some of the sensations that cause problems after stroke.

Pursuing activities that drive joy addresses the challenges of stroke on multiple levels.

Links

Where do we go from here?

More thoughts from Brendon

A redsquare with the Strokecast logo and Brian Haslam's headshot. The text reads "What is chronic pain? New episode on your favorite podcast app http://Strokecast.com/pain"

A redheaded woman paws at her face in agony. The text over the image read: Pain is actually an experience that our body, our brain, our whole nervous system sort of basically generates as a means of self-protection. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A collection of audio cables plugged into some sort of breaker box. The text over the image read: Pain as an input -- as a sensation -- is actually not correct anymore, but more pain as an output like an emotion. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A tiger lurks in an algea covered pond The text over the image read: We attribute an experience of pain to a body part that we view is currently under danger. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A black and white photo of lots of people walking down a city street The text over the image read: 20-25% of the general population in the world experiences ongoing pain. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of walnut that looks similar to a brain in its skull. The text over the image read: The ultimate decision of whether you experience pain is determined by your brain, but it is a as a result of a lot of different information coming in from different systems and how that is processed. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of a woman clutching the back of her neck in pain The text over the image read: People with stroke, unfortunately, are two to three times more likely to experience chronic pain than someone without a stroke. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of several people wearing HazMat suits The text over the image read: Pain is the is an ultimate way of protection because it makes me do things differently. It will make me stop interacting with that stimulus. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of a volume knob set to 10 The text over the image read: So when information gets into the central nervous system, basically the volume switch gets ramped up. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of 2 young stiudies reading large, thin books while standing in an ethereal forest. The text over the image read: Ongoing pain becomes a learnt process and a bit like a skill acquisition. The body becomes, or the self becomes, incredibly skilled at evoking a protective behavior such as pain in order for it to feel safe. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of a cloverleaf interchange The text over the image read: Pain should just be thought of as part of the whole situation, rather than something out on its own. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of two security cameras mounted on a wall. The text over the image read: Pain is a good thing for a lot of situations. It's designed to make us safe. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A pictrure of multicolored loops of light. The text over the image read: We need to be thinking of pain as a normal experience as part of our day-to-day sort of things and an important one in the right context. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of a person wearing a hoodie standing in front of a brick wall at night. The text over the image read: You will experience pain if there is more evidence of danger than there is of safety. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of three empty beds in a hospital ward. The text over the image read: Very few people who experience ongoing pain following their stroke experience pain in the early days in that acute setting. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of a padlock securig two aquamarine doors. The text over the image read: It's not actually the stroke itself that has caused the pain, but maybe the stroke has created an environment where it's perceived to need more protection. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A picture of a woman holding a finger in front of her mouth to shush the viewer. The text over the image read: A system post stroke can be overwhelmed because it loses the ability to quiet down information that isn't relevant to the task. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

An illustration of multicolored nerve cells. The text over the image read: And we're now sort of going into sensory retraining as a means of reducing pain and increasing function. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A black and white photo of a hand held up with the palm facing the camera and the fingers slightly curled. The text over the image read: How do people with stroke perceive the size or the shape of their body part?... Those that had chronic pain, were much more likely to report that their hands now felt two different sizes. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A person touches a lake with the back of their hand. The text over the image read: The hand is really crucial to how we perceive our environment, second probably only to vision. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.

A person holds up a stone with the word believe painted on it. The text over the image read: You can do all the best treatments in the world, but if it doesn't fit with what that person believes is actually going on, they will not work. - Brendon Haslam Of course chronic pain sucks after stroke. But it also changes how big you think your hand is. Pain researcher and PhysioTherapist Brendon Haslam talk about the nature of pain after stroke, what happens neurologically, and the latest research in this episode. Visit http://Strokecast.com/Pain to learn more.


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