Visceral pain relates to pain in the organs of the body, so it could be the chest, or more likely, the abdomen or the pelvis. It is somewhat unlike other pain syndromes in a sense that visceral pain activates the autonomic nervous system, specifically the parasympathetic nervous system or the sympathetic nervous system or both, which is why a lot of patients who have visceral pain also have associated nausea, vomiting and sweating. More women than men suffer from visceral pain and specifically from chronic pelvic pain; pain that comes from the organs such as the bladder, the uterus, the fallopian tubes, the ovaries or in men, from the prostate.
If someone has chronic pelvic pain, he or she may also have concurrent fibromyalgia or concurrent interstitial cystitis, so there’s a lot of overlap among the chronic visceral pain syndromes. Many patients who have visceral pain and specifically chronic pelvic pain also have concurrent depression and anxiety. It can lead to a lot of familial discord and sexual difficulties among partners.
Visceral pain can be hard to localize because of something called viscerosomatic convergence. Think of the nerves that would start from the small intestine, travel from the small intestine all the way to the spinal cord, say at level T10. Those are called visceral afferent fibers. Well, there are cutaneous nerve fibers that will also start, say, from the skin and travel from the skin to the same spinal cord segment, say T10. Those nerves that travel from the skin converge at the same level in the same location as the nerves that travel from the gut and end up in the spinal cord. That’s called the viscerosomatic convergence of nerves and is why patients will, say for example, they have belly pain and at the same time, they may feel like they have referred pain in the low back.
Patients with visceral pain may be put on opioids, both long-acting opioids short-acting. They can be moderately effective, but there is emerging evidence that other medications like the tricyclic antidepressants such as amitriptyline or doxepin, or the gabapentinoids, for example gabapentin or pregabalin, can be useful in treating visceral pain as well.
There are a host of injection therapies that we use as pain specialists that can be helpful. A celiac plexus nerve block can be helpful for patients who have intractable pancreatic cancer or who have intractable pain from organs like the liver or the pancreas or the gallbladder. There’s another plexus called the superior hypogastric plexus and that receives input from organs like the prostate, the bladder, the uterus for example, the vagina in women or the testes in men, so for those patients who have chronic, perhaps benign pain or cancer pain in those regions, a superior hypogastric plexus block can be very useful. And there’s more evidence now that spinal cord stimulation can be helpful; dorsal column stimulation can help patients who have persistent pelvic pain via different approaches or even a condition like pudendal neuralgia that can cause pain in the sitting bone area or the anal region or the area between the anus and the vagina in a woman, which would be called the perineum. So those neuromodulator devices I think are important for frontline practitioners to know about for referral purposes.