Pain threshold VS Pain tolerance
And other pain issues
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"There is a huge misconception that still exists when it comes to understanding the degree of pain people with Fibromyalgia experience. The reason for this confusion is that there are actually two separate terms used to describe levels of pain. The term “pain threshold” defines the level at which the body first perceives a stimuli as being painful. The term “pain tolerance” has a completely different meaning and basically defines how much pain a person can actually take without breaking. We can think of tolerance as the “acceptance level” of an existing pain." Fibrocare Center

Now, why do these two terms cause us so many problems ? Well, one thing is that in the common mind, they tend to be used interchangeably, even some doctors will make this mistake. And it is a major mistake. As one form, Pain tolerance, means just as it says ... how much pain can we take ? Well, for those of us with FM, we are the Olympic athletes of pain, given our ability to "tolerate pain" We put up with more pain on an average day, than most people would in a month.

But our pain threshold, meaning the level at which we perceive pain, is much lower. The short explanation is that it is due mainly to the sheer amount of substance P in the spinal column, which in most people with FM stands at 3-5 times as much as normal. This is why FM is classed as a pain amplification problem. Further, our nero chemistry is out of whack so the brain does not process pain signals in the manner that it should, mainly by not filtering them out. Moreover, our nervous systems also does not filter out input, rather, it grabs on to it and tends to make it worse. Collectively, this is called Hyperalgesia. ( see definitions further down )

Moral Values :

Now we run into another problem however, which is a "moral" value to these words. As they both tend to be perceived, as weakness. To be "stoic" in the face of pain, is considered a moral virtue. Well, if you look at what we really have to put up with everyday, we must be the most virtuous people around :) But since we constantly demand something for the pain, we are seen as weak, unable to handle pain, etc. A real catch 22 going on here.

Now comes in a further problem, the idea that since we become " accustomed" to pain, that somehow, we feel it less. Not so:

Effects of exposure to pain

"It is widely believed that regular exposure to painful stimuli will increase pain tolerance – i.e. increase the ability of the individual to handle pain by becoming more conditioned to it. However, this is not true – the greater exposure to pain will result in more painful future exposures. Repeated exposure bombards pain synapses with repetitive input, increasing their responsiveness to later stimuli, through a process similar to learning. 

Therefore, although the individual may learn cognitive methods of coping with pain, these methods may not be sufficient to cope with the boosted response to future painful stimuli. "An intense barrage of painful stimuli potentiates the cells responsive to pain so that they respond more vigorously to minor stimulation in the future.  Wikipedia

Which leads to pain sensitization, "central sensitization, where nociceptive neurons in the dorsal horns of the spinal cord become sensitized by peripheral tissue damage or inflammation. This type of sensitization has been suggested as a possible causal mechanism for chronic pain conditions."

FM and body damage:

Now, the problem with that explanation, is the overwhelming assumption that FM causes NO body damage. This concept has been challenged on several levels, in that yes, damage is being done, but it is happening at a mainly cellular level. For example, muscle tissue takes on a moth eaten appearance, due to cell disruption  
Mycoplasmasmic Infections on site link, and other nerve damage, that can be seen and proved are often considered the reason. As well as many others.

It is not what is called gross damage, meaning causing deformity or easy to see. No such luck. If the signs of damage were easy to see, they would also be easy to spot and therefore, treat. But you need a microscope to even see the damage being done in most cases and of course, you have to be looking for it in the first place.

Pain amplification issues :

Ok, off into a short dip into more medical geek here .... to define these ideas even further.


Are nerve sensations that can feel like  things are crawling under your skin, tingling, as if the body part "fell asleep" and is now waking up, burning ( the feet being a prime target ), itching, numbness and of course, pain. Paresthsias is associated with
peripheral neuropathy, multiple sclerosis, diabetes, migraine, FMS, ME, and CFS.

Allodynia :

Where, at the skin level, otherwise normal sensations, are felt as pain.

"Associated with a handful of conditions, including neuropathy, postherpetic neuralgia (shingles) and migraine on site link. Allodynia is believed to be a hypersensitive reaction that may result from the central sensitization associated with FMS. The pain signals originate with specialized nerves, called nociceptors, that sense information about things like temperature and painful stimuli right from the skin."

Allodynia comes in 3 forms

  • Tactile, which is pain from touch
  • Mechanical, which is from something moving across your skin
  • Thermal, which is pain from heat or cold, that does no perceptual tissue damage
Pain amplification syndrome:

"Is a condition that develops when the nervous system gets used to carrying pain signals and continues to so, long after the cause of the pain is gone. Pain signals can become embedded in the spinal cord, as a painful memory. Trauma turns on pain signals, which alert us and at the same time mobilizes our internal resources. Once the trauma is resolved, the alarm goes off, no more pain. When the alarm does not go off, a loop is created between the nervous system and the brain. The nerves keep firing and send electrochemical signals to the brain and they are interpreted as pain. The longer the loop continues, the stronger the pain signals are amplified."Blanche Scharf

Pain hypersensitivity: Link

There are two forms: Both of which are defined above, which results in

  •     Thresholds are lowered so that stimuli that would normally not produce pain, are now painful (allodynia).
  •     Responsiveness is increased, so that painful stimuli produces an exaggerated and prolonged pain (hyperalgesia).

Peripheral sensitization:

"Peripheral sensitization is a reduction in threshold and an increase in responsiveness of the peripheral ends of nociceptors, the high-threshold peripheral sensory neurons that transfer input from peripheral targets (skin, muscle, joints and the viscera) though peripheral nerves to the central nervous system (spinal cord and brain stem)."

Central sensitization:

"Central sensitization is an increase in the excitability of neurons within the central nervous system, so that normal inputs begin to produce abnormal responses."

Now, what does all of that mean, in English ? Our central nervous system in FM has major issues. It has considerable difficultly in processing pain signals, mainly that it over amplifies them. Now where does the CNS get its information from ?

From the peripheral ends ( meaning the tips ) of nociceptors, which are the specialized cells, that send impulses to the CNS of pain, and most other body sensations. Now, the problem in FM is that both systems do not work very well so the signals are not only scrambled from the source, they are way "louder" than they should be. Nor do they shut off as they are supposed to. 

Then, to top it all off, once these totally trashed signals reach the brain, the brain itself, has some serious problems, handling pain input as there have been literal synaptic changes to the brain ( see brain and FM on site link ). Hence we get the endless loop of pain signals we see in FM, the one that never shuts up.