Visceral pain: a forgotten topic
Prof. Fernando Cervero from Montreal, Canada discussed at the EFIC 2013 in Florence an under served but very important topic, which is visceral pain.
Visceral pain is very under served. As patients often visit organ specialists not interested in pain itself, but directly focusing on the underlying illness. However, as it is a Cinderella in the pain field, and it can stick also after treating the illness, it needs much more attention. In definitions of pain, we miss the focus on visceral pain.
Endocannabinoids in visceral pain
Visceral nociceptics are very specialized, are intensity encoders as well as high threshold receptors, they are also chemo sensitive (ischemia) and profoundly influenced by the micro environment.
Furthermore, the role of non- neuronal cells is especially important. For instance the urothelial cells have TRPV1 receptors and produce transmitters such as ATP, creating experiences of fullness, voiding etc.
The cannabinoid agonists for instance can reverse sensitization via intravescular pressure, making clear the importance of the endocannabinoids in regulating such visceral processes.
Palmitoylethanolamide (PEA) is the only endocannabinoid which can be administered as a supplement, and thus might have an important role in the treatment of visceral pain.
Working of the brain
Chronic pain and morphological changes occur with long-lasting effects, for instance after ovariectomy. A chronic visceral pain state develops step by step even into structural changes in the brain. These changes are reversible if the pain is treated correctly.
Professor Cervero stressed that the study of visceral pain can offer insights into the workings of the brain. That may be complementary to what we know from studies of somatic or neuropathic pain. Also, the treatment of some forms of this pain is now oriented more towards the neurological system that mediates the pain, than towards the underlying disease of the organ.
This is particularly relevant in conditions such as the irritable bowel syndrome where treatment is often directed to the nervous system rather than to the gastrointestinal tract.
October 2013, prof. dr. Jan M. Keppel Hesselink