The first association between Fibromyalgia Syndrome (FMS) and interstitial cystitis was published in 1997 noting the similarity in the clinical course of both diseases and speculating the same types of mechanisms may be operating in both disorders. Up to 17% of FMS patients have symptoms consistent with IC. From a more general perspective, urinary frequency, urgency and the need to have to wake up and urinate at night occur in greater than 50% of FMS patients.

What causes IC is still not known. One model proposes that damage to the bladder epithelium initiates something called neurogenic inflammation. Neurogenic inflammation is an irritation of the nerves that respond to pain. In particular, a type of nerve called the c-fibers. These are rather special nerves that you will read about in a future short report. The reason they are special is because they contribute to a rather important pain condition that is thought to be at the heart of FMS, a phenomenon called central stimulation.
Stimulation of the c-fibers causes some rather significant changes within the central nervous system, both at the level of the spinal cord and also within the brain. They will be the topic of their own short report. To pique your curiosity, within the spinal cord, the c-fibers result in something called “wind-up.” As a result of “wind-up” the central nervous system undergoes a restructuring called central sensitization. You’ll find out just how profound this restructuring turns out to be in the short report on central sensitization. Briefly, central sensitization may explain just about all of the pain experienced in FMS.

When the c-fibers are stimulated they help cause a group of cells called “mast” cells to release products that produce inflammation; hence the term neurogenic inflammation. Mast cells will release a number of compounds, some of which are histamines – the products that will give you a runny nose, itchy eyes, and other symptoms of an allergy. That’s because mast cells are found just about everywhere – in your respiratory tract, digestive system, and in the lining of the bladder.  There are some thoughts that neurogenic inflammation may be contributing to other symptoms of FMS by virtue of mast cells being in other parts of the body. For example, mast cells in the lining of the digestive system may be contributing to the symptoms of irritable bowel syndrome.

That’s why patients with IC also frequently suffer from irritable syndrome (IBS), one study showing that FMS with IC have up to eleven times the risk of also having IBS. Laboratory studies were done on animals to find out exactly where the nerves originated that provided information from the bowel and bladder.  What was found was rather surprising. A single sensory nerve from the spinal cord actually sends branches into both the bladder and the intestines. This meant that if one organ was irritated it would “confuse” the nervous system into thinking both organs were irritated. Your brain would “feel” pain in both the intestines and the bladder, even though only one structure was actually hurting.  This is similar to having multiple phones in your hose – you don’t know in what room someone had answered the phone; it’s the same phone line. This could account for the high correlation between the two conditions.
IC is also a potential cause of sexual pain and women may have a combination of dyspareunia (the medical term for pain during intercourse) and chronic pelvic pain. Given that the bladder and pelvic muscles share common nerve pathways it is not unusual for flares of IC to be associated with dyspareunia.  Dyspareunia may persist for days after intercourse in over a third of women.  The effects can be substantial as one study of FMS patients reported up to 54% of women “avoid intimacy with their partners most of the time.”  A second survey found 19% of women unable to tolerate intercourse completely.   

IC is a pain condition that has had only partial success in the past with medications or conventional therapies. Pain physicians, however, have a unique treatment that only individuals trained in interventional pain management can provide. This technique was described in the short report on Sexual Dysfunction and Fibromyalgia. It is called a Superior Hypogastric Nerve Block. The pain from the bladder region may be relieved by a specific injection to a group of nerves that are a type of way-station to the sensory nerves coming from these organs. This way-station is called the superior hypogastric plexus. These nerves live in bundle in front of the last lumbar vertebrae just where it attaches to the sacrum, or hip bone. A needle is placed exactly next to this bundle by a pain physician using a fluoroscope. After a small amount of dye is injected to verify the location a mixture of a numbing anesthetic and steroid compound is injected. This mixture is designed to “settle-down” the nerves so they are less active.

This is a relatively new approach and was first presented at the American Academy of Pain Medicine’s annual meeting in 2006 by pain physicians from the University of Colorado. Of the patients receiving the procedure, 75% received significant relief of their symptoms. If you feel you are suffering from this type of pain condition, it is time to discuss this with your pain doctor. There is no reason to continue suffering.