There are a few diseases that cause an insensitivity to pain. This question asks about the relationship between the cold and pain, which got me thinking:

Is shivering a response driven by the sensation of cold, or a response to the pain associated caused by the cold? This is easy to work out by considering people that do not experience pain.

The key here is if people with congenital analgesia (AKA CIPA, CIP) shiver then we may assume that it is the sensation of the cold, not the pain and the cold, that causes the shivering.

  1. Do CIPA patients shiver in the cold?

  2. Does this mean that the shivering is caused by sensation pathways or pain pathways?

Disclaimer: I am not an anatomist and do not claim to have a working knowledge of the nervous system. Please point out any and all obvious errors in this question that might explain why this wouldn't be the case in the comments or as an answer if its a big error.

  • $\begingroup$ There's an awful lot on hyperthermia in CIPA individuals, but not a lot on hypothermia. My personal expectation would be a delayed reaction due to cold misperception, but an induced shivering response as core body T drops below critical values, because shivering is a motor reponse. $\endgroup$
    – CKM
    Feb 10 '15 at 17:06
  • $\begingroup$ Thats interesting to note. I suppose hot things are more dangerous to CIPA sufferers than cold things, so thats where the research goes. $\endgroup$
    – James
    Feb 10 '15 at 17:08
  • 1
    $\begingroup$ An apropos: I've read that some people who are born insensitive to pain is actually overly sensitive to cold. I read of the mother of a pain-insensitive boy who would soak him in cold water whenever he intentionally hurt himself, in an attempt to condition him to associate self-mutilation with something unpleasant $\endgroup$
    – Abulafia
    Feb 11 '15 at 11:43

Interesting question. Here what I think (I am not an expert in congenital analgesia so take it with a grain of salt).

The pain provoked by an high temperature is mainly transmitted via the receptor TRPV1 (a Ca2+-channel nocireceptor) while cold sensation is driven by TRPM8 and possibly, for noxious cold, via TRPA1 (two similar types of Ca2+-channels). Those receptors are known as the temperature sensors. As an anecdote, TRPV1 is what give you a pungency sensation when eating spices while TRPM8/TRPA1 give you the cooling sensation from mint.

Mechanical pain is transmitted via other receptors, including TRP channels, but this is not fully understood at the molecular level.

As far as I know, the encoding of pain, and more generally physiological sensations, in the brain are also not yet fully understood but it is very likely that the pathways taken by TRPV1 differs from the one taken by TRPM8/A1 which would suggest that it is possible that CIPA individuals experience high-temperature pain and cold differently at the molecular level and therefore might respond, to some degree, to one but not the other. This also probably applies to mechanical pain vs temperature-driven pain.

I would actually not be too surprised if CIVA people shiver even if not feeling any temperature sensations. Would be interesting to have the opinion or even better the observations of experts in this field.

P.S. I know this is not a definitive answer but I have not enough reputation to comment.


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