This page uses content from Wikipedia and is licensed under CC BY-SA.
|Congenital insensitivity to pain|
Congenital insensitivity to pain (CIP), also known as congenital analgesia, is one or more rare conditions in which a person cannot feel (and has never felt) physical pain. The conditions described here are separate from the HSAN group of disorders, which have more specific signs and cause. Because feeling physical pain is vital for survival, CIP is an extremely dangerous condition. It is common for people with the condition to die in childhood due to injuries or illnesses going unnoticed. Burn injuries are among the more common injuries.
For people with this disorder, cognition and sensation are otherwise normal; for instance, patients can still feel discriminative touch (though not always temperature), and there are generally no detectable physical abnormalities.
Because children with the disorder cannot feel pain, they may not respond to problems, thus being at a higher risk of more severe diseases. Children with this condition often sustain oral cavity damage both in and around the oral cavity (such as having bitten off the tip of their tongue) or fractures to bones. Unnoticed infections and corneal damage due to foreign objects in the eye are also seen.
It may be that the condition is caused by increased production of endorphins in the brain. In this case, naloxone may be a treatment, but it does not always work. In all cases, this disorder can be in the voltage-gated sodium channel SCN9A (Nav1.7). Patients with such mutations are congenitally insensitive to pain and lack other neuropathies. There are three mutations in SCN9A: W897X, located in the P-loop of domain 2; I767X, located in the S2 segment of domain 2; and S459X, located in the linker region between domains 1 and 2. This results in a truncated non-functional protein. Nav1.7 channels are expressed at high levels in nociceptive neurons of the dorsal root ganglia. As these channels are likely involved in the formation and propagation of action potentials in such neurons, it is expected that a loss of function mutation in SCN9A leads to abolished nociceptive pain propagation.
Developmental disabilities such as autism can include varying degrees of pain insensitivity as a sign. However, since these disorders are characterized by dysfunction of the sensory system in general, this specific condition is not in itself an indicator of any of these conditions.
The opioid antagonist naloxone allowed a woman with congenital insensitivity to pain to experience it for the first time. Similar effects were observed in Nav1.7 null mice treated with naloxone. As such, opioid antagonists like naloxone and naltrexone may be effective in treating the condition.
In the Millennium series by Swedish author Stieg Larsson, the character Ronald Niedermann is presented as having the condition, rendering him an overtly stereotypical henchman, which includes precipitating several plot devices in the series.
The disorder has been portrayed in television shows and video games. In the season 3 episode of House M.D., "Insensitive", they treat a patient with the condition.
In the Japanese anime and BL game, DRAMAtical Murder, a supporting character named Noiz has this disorder. When he was younger, his parents considered him a disgrace because he would play rough with other children because he didn't understand what pain felt like. The only pain he could feel was from his tongue.
In season 3 of the TV-series Perception episode "Painless", there is a crime involving someone with the condition.
In Act I, Scene III "This Hurts" of the Off-Broadway play Almost, Maine, the character Steve has this disease. His brother Paul teaches him what is supposed to hurt, which he writes in a book. After he falls in love Steve gains the ability to feel pain.
In season 3 of Grey's Anatomy episode "Sometimes a fantasy", Dr. Alex Karev was treating a young girl with this condition.
In the 2008 video game Dark Sector, protagonist Hayden Tenno has from this condition. This becomes a plot point when he is infected by a virus that drives most people insane due to the severe pain it causes in victims, which he is unable to feel.