Since then, she has added an unfortunate variety of words to her vocabulary: Her hips “hurt” and “ache;” she feels a “continuous buzzing in both legs and a vice-like squeezing in the pelvis.” When resting, she is left with “tingling” and “electric shocks.” She now has headaches, backaches, period pains, and stomach cramps; and even describes “the sting” of a graze and “the sharpness” of an exposed gum.
According to doctors who treated her, the woman's sensitivity to pain -- tested on the tops of her feet -- is 10 times higher than it was before she gave birth.
Congenital insensitivity to pain is an incredibly rare genetic disorder — there are only 20 recorded cases — that causes individuals to be totally unaware of pain. Co-author of the paper Michael Lee explained how pain pathways start with specialized nerves, called nociceptors, that sense damaging temperatures or pressure and then fire off signals to the brain. Those signals make us feel pain to prevent further damage. In people with CIP, a defective gene prevents these signals from going through.
But pain can also arise when nociceptors or nerves are damaged, as was the case when this woman’s lumbar nerve was pinched during childbirth.
“You’d expect that they would stop working, but the opposite happens," Lee said. "What’s left starts to fire off randomly, leading to exceedingly unpleasant sensations. Our case suggests the genetic defect doesn’t protect against neuropathic pain, and that these patients can appreciate pain. The correct terminology really isn’t congenital insensitivity to pain, but congenital absence of nociception.”
While CIP might seem like a fantastic malady, it’s actually quite dangerous. People with the condition can tell hot from cold, but can’t sense when they’re getting burned. According to the National Library of Medicine, this lack of sensitivity “often leads to an accumulation of wounds, bruises, broken bones, and other health issues that may go undetected; these repeated injuries often lead to a reduced life expectancy.”
Scientists want to know if it’s possible to target the CIP gene to create new pain relief therapies. According to Lee, therapies modeled after the CIP gene would only go after nociceptors, while drugs currently in use can target the muscle, heart and brain if not used in small doses or near specific nerves. Drugs targeting nociceptors could be given orally or intravenously since they wouldn’t affect other organs. “They might be useful for pain from acute injuries, though our case suggests they’ll be less effective for neuropathic pain," Lee said.
Only one other case of a patient with CIP experiencing pain has been reported.
Olivia Campbell is an editorial assistant at Vela Magazine and a freelance science and culture writer whose articles and essays have appeared in Pacific Standard, Brain, Child Magazine, The Daily Beast, and GOOD Magazine. Find her on Twitter.