Neurons and pain

Pain is defined as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in these terms." Oddly enough, there are no neurons whose sole function is to transmit painful information from the viscera. Of course, we recognize visceral pain, but it is detected by neurons that are sensitive to cutaneous stimulation . That is, they will perceive sensitivity in a defined area at the skin level. As a result of this arrangement, disorders of internal organs are sometimes mistaken for pain in a cutaneous area .

Referred pain

It may also happen that a patient consults for a painful sensation felt in a place other than its actual location, a phenomenon known as referred pain . The most common clinical example is that of angina pectoris where the painful sensation, due to insufficient irrigation of the heart muscle, is projected towards the top of the rib cage with irradiation towards the left arm and hand.

Other important examples concern different types of pain, such as:

• the gallbladder , projected onto the shoulder blade region,
• the esophagus , projected onto the rib cage,
• the ureter (due to the passage of a kidney stone), projected onto the lower abdominal wall,
• the bladder , projected onto the perineum and,
• appendicitis pain, projected to the front of the abdominal wall, around the navel.

Knowledge of these phenomena allows us to diagnose the real cause of such painful sensations, although it would be easy to be mistaken.