Most pain sensitization is simply a reaction to pain itself, a more-or-less normal, common, and reversible reaction to chronic pain. But it’s also possible for the pain system to spin out of control and severely over-react to stimuli because it’s “sick,” a disease in its own right. The example of this is complex regional pain syndrome, which causes extreme pain, usually in a limb, and usually following some relatively minor tissue insult like an insect bite, a minor cut, or a small fracture.
When it’s full-blown, the severity of this problem is impossible to understate (suicide is common), and yet there probably are milder variations of it. Many times in my career I have become quite convinced that a patient had to be suffering from some lesser form of CRPS, awful but not enough to clinch a CRPS diagnosis.
Myelopathy and dysautonomia
An irritated spinal cord — usually irritated by being slightly pinched by a narrow spinal canal — can cause an astonishing variety of problems, including pain, without ever clearly giving itself away. Symptoms can be in virtually any location in the body, if the location of the trouble is high in the spine. This can go on for years, bad enough to cause pain but never bad enough to be easily diagnosable.
Worse, there’s some intriguing evidence that “minor” irritation of the upper spinal cord may be uniquely problematic, causing “ dysautonomia ” — excessive sympathetic arousal, causing you to react as if stressed. 19 This weird low-grade crazy-making effect is new and still uncertain, but it is nicely consistent with the much firmer, recent discovery that the autonomic nervous system is very disturbed in the aftermath of major spinal cord injuries, causing organ failure 20 — a clinical reality historically overshadowed by the seriousness of paralysis. Subtle dysautonomia from chronic mechanical irritation of the spinal cord is definitely a plausible, sinister, and thoroughly obscure explanation for some chronic pain and anxiety.
Claudication: the pain of impaired blood flow
Sometimes an artery gets narrowed or pinched off and causes serious pain. Although simple in principle, it tends to get missed in younger people, where it’s a relatively rare problem, and so the suspicion falls on other things. It also gets missed because “musculoskeletal” is a realm of medicine where circulatory function is rarely considered at all. But it should be an easy diagnosis: claudication tends to cause a deep aching pain exclusively with exertion (when tissues are demanding oxygen), which isn’t how most musculoskeletal problems behave. Here’s a good story about this kind of pain and its misdiagnosis …
A patient had sciatica-like leg pain for thirty-five years and was misdiagnosed many times until finally getting not only a definitive diagnosis but a cure. 21 He had a narrowed artery (arterial stenosis causing “claudication,” the pain of impaired circulation). That’s it! Not even a difficult a diagnosis in the end, really. There were some pretty glaring clues there that got ignored by a lot of people who should have known better.
But not only was he misdiagnosed many times over more than three decades, he was misdiagnosed fashionably: that is, each misdiagnosis neatly fit a paradigm in physical therapy (better than it fit his symptoms). This carried on right up to and including the present day fascination with psychosocial factors and sensitization (which served him no better than any of the other paradigms had). Taylor and Kerry :
Interestingly, the patient’s belief that something ‘was actually wrong’ had remained with him throughout the journey. This, of course, had been explained away to him (more recently) by current research and evidence-based thinking on central sensitization and pain.
Just fascinating. The authors thoughtfully explore the implications of this rather shameful episode. The bottom line? Good diagnostic skills are never out of fashion. Or shouldn’t be, anyway! 22
Hypermobility spectrum disorders and Ehlers–Danlos syndrome
Hypermobile patients get hurt easily and have a lot of chronic body body pain. 23 There are many types of hypermobility, with a wide range of severity, from trivial party trick flexibility in one or two joints (“double-jointed”) with no apparent consequences — especially early in life — all the way to full-blown genetic disorders of the connective tissue with many serious medical consequences. There’s a huge gray zone in the middle of under-diagnosed and under-treated people, who are definitely having problems but may never figure out why or what to do about it.
Hypermobility spectrum disorders (HSD) are a group of conditions defined by joint hypermobility — unexplained joint looseness. HSD is a bucket diagnosis for people with symptomatic hypermobility, but without a connective tissue disorder that explains it, like Ehlers–Danlos syndrome or Marfan syndrome. Most connective tissue disorders are relatively obvious, but EDS can easily evade diagnosis, making it a prime suspect in many cases of chronic pain…
Exactly the wrong therapy If a lot of chronic body pain is caused by subtle diseases that make connective tissue fragile, consider how tragically misguided it would be to try to help by vigorously stretching their connective tissues! And yet that’s exactly the point of “fascial release,” an extremely popular form of massage therapy. See Does Fascia Matter? A detailed critical analysis of the clinical relevance of fascia science and fascia properties
Ehlers–Danlos syndrome (EDS) is a group of conditions that includes hypermobility along with fragile tissues that injure easily and heal poorly (especially skin), with many consequences. The most common form of EDS is hypermobile EDS (hEDS). It’s tricky to distinguish hEDS from HSD. 24 However, hEDS is probably associated with serious rheumatic diseases (i.e. psoriasis, ankylosing spondylitis, rheumatoid arthritis)… and this is fresh science and very likely to be missed, “perhaps due to a lack of gravitas surrounding the HEDS diagnosis.” 25
Given the musculoskeletal troubles that we know hEDS can cause, it is reasonable to guess that less severe hypermobility (HSD) may also be both clinically important and yet even less obvious.
So, hEDS/HSD is serious … but it’s not taken seriously. Even doctors who know about hEDS/HSD usually assume that it’s mostly a minor condition, and would definitely not refer patients on to a rheumatologist.
Vitamin D and magnesium deficiencies
There is not a single supplement or anti-inflammatory superfood that is clearly beneficial for any common kind of pain, but there are a couple nutritional deficiencies that stand out as significant, legitimate suspects in many chronic pain cases. Pain may be the only clear symptom of either one.
Vitamin D deficiency is on the firmest ground. It is probably more common than once suspected — at least 1 in 20 people in the lowest estimates, 26 and possibly many more. 27 It can cause subtle widespread pain that may be misdiagnosed as fibromyalgia and/or chronic fatigue syndrome, including symptoms like muscle and bone aching, 28 fatigue and weakness, lower pain threshold, and more acute soreness after exercise that is slower to resolve. For more information, see Vitamin D for Pain .
Magnesium deficiency is also a suspected factor in chronic pain, especially migraines. 29 Some people are aware that magnesium supplementation is the specific rationale for Epsom salts : a form of getting the stuff into your body that is of very dubious value (especially compared to straightforward oral supplementation). Ironically, magnesium (in a clinical setting) is known to induce cramping and severe muscular pain, so none of this biology is straightforward!