In the Absence of Pain

When I was little I remember wishing that I could not feel pain. This sensation normally came after stubbing my toe, or a shot, or some other quick stinging pain. It would have made life so much easier to not have to be held back by pain. However, I now understand how useful pain is to the body. House did an episode of a girl who could not feel pain, and in typical House fashion there was of course something more life threateningly wrong with her. This episode got me thinking about the causes of not feeling pain, and this article is what resulted.

Congenital Analgesia, or indifference to pain is a rare condition causing lack of pain sensation, but not other sensations. There have only been 100 cases in the US since 1932, and unfortunately the exact cause of the condition is unknown. However, due to frequencies of occurrences it is believed that the gene is autosomal recessive, but it may be caused by more than one allele.

I was surprised to find that there are other conditions with similar effects and one of them is congenital insensitivity to pain with anhidrosis (CIPA). This condition is caused by a mutation of the NRTK1 gene and results in a decreased number of small myelinated and unmediated nerve fibers. People with this condition also lack sensitivity to temperature change and cannot regulate body temperature by sweating. A third condition is hereditary sensory and autonomic neuropathy type 5 (HSAN5). This is different from CIPA in that individuals with HSAN5 do not have anhidrosis. It also appears to be caused by an autosomal allele.

After reading the article I was very surprised to find that the exact causes are unknown, especially considering the potential of self mutilation from an unknown injury. Any further research in this matter may even be used to develop new ways to block pain.

http://serendip.brynmawr.edu/bb/neuro/neuro06/web1/aschmid.html