There is an ongoing academic debate between researchers and clinicians about whether or not nociception is necessary for pain or if pain can exist without nociception. The problem is a lack of experimental research on the phenomenon, and some use this lack of evidence to argue that nociception is necessary for pain.
However, positive and negative claims are unsupported without any experimental research on the phenomenon. This means that both the claim that nociception is necessary for pain and that nociception is not necessary for pain are unsupported. Excellent researchers try to disconfirm their assumptions; however, pseudoscientific researchers will only try to confirm them. In the case of whether or not nociception is necessary for pain, no such disconfirmatory research has been done. There is, however, a high likelihood that some nociception is necessary for most pain.
But as noted by Dr. Bronnie L. Thompson, PhD: “Nociceptive activity may occur at lower stimulus intensity for people with nociplastic pain (also neuropathic pain) – and actually, even inflammation reduces the nociceptive firing threshold. So it’s not so much whether peripheral nociception is necessary but whether the amount of stimulation needed for nociceptive activity is consistent. It’s not – less mechanical pressure, lower temperature is needed for nociceptive activity in people with fibromyalgia is already well established.”
So, we know that nociception is a strong modulator of pain and that we can have nociception or an injury without any pain. We have known this for some time (Banzett et al., Melzack et al., Lopez et al.). But considering the amazing complexity of the brain and the many other phenomena it can produce, like supernumerary limbs (Tanaka et al.), synaesthesia (Banissy et al.), foreign accent syndrome (Kurowski et al.), lilliputian hallucinations (Blom et al.) or “normal” hallucinations (Kim et al., Huang et al.), to name a few. The likelihood that pain can exist in some rare cases without any nociception also increases.
The nociception debate has little clinical value
However, the “nociception is necessary for pain” debate severely decreases its clinical value when you realize how little nociception matters for the amount of pain experienced (Main et al., Fillingim et al., Moseley et al.). This is further decreased by the fact; that there is no isomorphic relationship between nociception and pain (Wall et al. 1985., Wall et al. 1986., Fillingim et al.).
A great example of how little nociception actually matters for the amount of pain experienced can be seen in an experiment where 321 healthy people were exposed to a standardized noxious stimulus (Fillingim et al.). Consequently, the amount of pain the individuals report varies dramatically, meaning there is a very high degree of variability between individuals even with a standardized noxious stimulus, see below.
Pain response (from no pain 0 to 100) to a standardized noxious stimulus in 321 healthy young adults, from Fillingim et al.
This is in line with what was noted by Main et al. some 30 years ago: “Pain is the single most common presenting complaint of patients attending hospital, and so the assessment of pain is of considerable importance in arriving at a diagnosis and deciding on a course of treatment. Yet some patients report extreme pain when there is apparently little or no evidence of tissue damage to explain the severity of their pain; and patients with a comparable level of tissue damage may differ widely both in the severity and nature of the pain they report.”
So, in summary, the jury is still out on whether or not nociception is necessary for pain, but there is a high likelihood that some nociception is necessary for pain. However, I would not be surprised that, in some rare cases, pain without nociception could exist. If we can hallucinate sounds that aren’t real, like footsteps, doors banging, or music, and see vivid scenes with people or animals that aren’t real, then why not also pain?
Sadly, the nociception is necessary for pain debate is a great sign of how indoctrinated health professionals are into the biomedical model. Unfortunately, it’s a big step backward toward a future where we provide person-centered care and accept we work with suffering human beings. Hopefully, we will someday accept that people are not neat packages of pathology, neuroinflammation, or nociception. But we are here to help suffering, worrying, fearful individuals. If we do not accept this fact, we are doing the very people we a supposed to help a disservice.
If we resist acknowledging this, we are putting our heads in the sand to what we have learned from the last 30 years of pain research, that pain is complex. Research has shown us that there are many factors impacting pain and that pain is a multi-factorial experience. If we assume that there is only one singular cause, like neuroinflammation or nociception. In that case, we fail to acknowledge the complexity of the brain and its fundamental role in what we experience.
The real losers in this event are the people we are supposed to help. Because when we choose to only focus on a singular cause of pain, we are simultaneously choosing to be blind to all other possible contributors to people’s pain. Thereby drastically reducing the possible solutions to people’s pain.
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