Asking patients about pain is a major component of an initial evaluation as well as with follow-up treatments. Monitoring changes in pain behavior, the intensity and the location can help gauge treatment success and progress. However, not a lot of people are aware of a major source of pain which is visceral pain. Kevin Hellman, PhD from NorthShore University Health System gave an excellent lecture at IPPS 2018 on visceral pain. Today, I’m going to share the information I gleaned from his lecture so that we can answer the questions of why does this happen and how does this happen?
Visceral pain is characterized by pain elicited from organs. Think pain from the bladder, the intestine, the stomach or even the heart.
There are several different mechanisms which cause visceral pain.
Hypersensitivity is when the tissue becomes more sensitized to a noxious (painful) stimulus. Think about it this way, if you were to poke your thumb with a thumbtack you would perceive a certain amount of pain as you push down on the tack which is a normal reaction. However, with repeated exposure the tissue on your thumb becomes more and more sensitive; this requires you to press less on the tack. Eventually your thumb is so sensitive that by just brushing your thumb by the tack you perceive pain. The same thing occurs with organs, with repeated exposure the tissue becomes more sensitive and is able to handle less intense stimulus.
This reflex is defined as increased tension and tone of the tissues in the abdominal muscles resulting from a painful stimulus to an organ. This is why if you experience intense intestinal cramping the muscles lying on top of your abdomen feel rock hard. It is important to treat not just the viscera themselves but the overlying skeletal muscle to reduce pain.
If high school or college chemistry was a distant bad memory let’s review what pH is and the purpose of it in our bodies. A pH level measures how acidic or alkaline something is, with 0 being completely acidic and 14 being completely alkaline, while a pH of 7 is neutral. The normal arterial blood range for a human is 7.35-7.45 depending on the source with the defined normal pH for a person is 7.4. The pH for the stomach is a lot lower – 3.5 since its job is to break down foods. The pH changes throughout the gastrointestinal tract – from a pH of 6 in the small intestine, to 5.7 in the caecum and a 6.7 in the rectum. The changes in pH throughout the tract are normal as the job of each organ changes. However, if your pH becomes altered this can cause significant pain and symptoms. Two of the studies Dr. Hellman cited demonstrated that patients with IBS have consistently altered pH levels throughout their colons.
Finally, what the heck do we do with all this information? How do we treat patients when all of these different mechanisms are working together to create pain?
Dr. Hellman did a great job concluding that a multidisciplinary approach is key to treatment. As of right now we don’t have the scientific tools to definitively determine which types of patients would benefit from which corresponding treatment. Therefore patients should be given a comprehensive evaluation and multimodal treatments should be used to target a patient’s symptoms. You’ll notice that Physical Therapy is listed as one of these key treatments!