A painful bladder condition known as interstitial cystitis is not at all what it seemed, scientists have discovered.
The pain seems to originate not in the bladder but in the colon, and the body miscommunicates the source of the pain to the brain. The finding could open up new treatments to the roughly 1.3 million U.S. residents, mostly women, who suffer from the condition.
Among other causes, spicy food, citrus and caffeine are causes of interstitial cystitis. The pain can be debilitating. Patients typically also feel an urgent need to urinate up to 50 times a day.
"This disease has a devastating effect on people's lives," said David Klumpp, principal investigator and assistant professor of urology at the Feinberg School at Northwestern University. "It affects people's relationships with family and friends." Klumpp said some women who suffer from this become so depressed, they attempt suicide.
Researchers had long believed the spike in the patients' symptoms was triggered when foods they had digested produced chemicals in the urine that irritated the bladder.
But the body can be strange, the new study shows.
Here's what Klumpp and his colleagues found:
Nerves in the pelvic region — the bladder, colon and prostate — are bunched together like telephone wires and plug into the same region of the spinal cord near the tailbone.
People with interstitial cystitis have bladder nerves that are constantly transmitting pain signals to the spinal cord: a steady beep, beep, beep.
But when the colon is irritated by pepperoni pizza or another type of food, colon nerves also send a pain signal to the same area on the spinal chord. This new signal is the tipping point. It ratchets up the pain message to a chorus of BEEPEEPBEEPBEEP!
"It was known that there was cross talk between organs, but until now no one had applied the idea to how pain signals affect this real world disease, how the convergence of these two information streams could make these bladder symptoms worse," Klumpp said.
The research is detailed in the September issue of Nature Clinical Practice Urology.
The findings suggest the pain can be treated rectally with an anesthetic in a suppository or gel, or perhaps an anesthetic patch applied to pelvic skin. Studies in back pain show anesthetic patches applied to the skin can reduce back pain, Klumpp said.
"We imagine a similar kind of patch might be used to relieve pelvic pain, which might be the best solution of all," he said.