Can the Brain cause Pain? How the Brain Handles Emotions
For a surprising number of pain sufferers, we are looking in the wrong place.
Posted April 6, 2014
You are probably aware that there are high rates of chronic pain in today’s world. The Institute of Medicine estimated that up to a 100 million people in the U.S. have some forms of chronic pain. Physicians get limited training about pain other than a basic understanding that physical injuries or structural abnormalities cause pain. Therefore, it is our job as doctors to find the culprit causing pain in order to eradicate it. However, pain is actually very complex, especially when it comes to the role of the brain and pain that has become chronic.
Let’s look at acute pain first. When an injury occurs, the damaged area activates nerve cells to send signals of distress to the brain. These signals are received in the automatic, subconscious parts of the brain for very rapid processing. This system functions to act in case of an emergency so that we will be able to quickly remove a hand from a hot stovetop. This very rapid processing occurs before the signal has time to reach the higher cortex for more complex decision-making.
It is the job of the amygdala and limbic structures of the brain to alert us in case of danger. An injury will typically cause the danger signal to activate, which in turn triggers the cortex of the brain to register pain. Thus pain is a response of the brain to a signal of danger. The actual experience of pain is in the head, not in the body. And, surprisingly, this is true of all forms of pain.
Can one have an injury without having pain? A friend of mine witnessed a man diving in the ocean for conch shells. After several dives, he emerged with a conch and proudly displayed it to his wife sitting on the beach. He was beaming in triumph. His wife wasn’t as thrilled for he had cut his legs in many places on the coral and was bleeding profusely. Pain only occurred after he realized that he was injured. This same phenomenon occurs when a child falls and may not cry until they see their parent. A study by Beecher published in 1951 found that a majority of injured soldiers reported no pain in the acute aftermath of military engagements.
On the other hand, pain can occur without an actual physical injury. In a well-publicized case, a British construction worker jumped off of scaffolding and was apparently impaled by a large nail, which went through his boot. His pain was tremendous and he required IV pain medication and sedation upon arriving at the hospital. When the boot was removed however, the nail had lodged between his toes and not into his foot. I can only imagine his reaction upon seeing that. Might he have exclaimed, “Oh, never mind.” A study by Derbyshire and colleagues showed that hypnotically induced pain was identical to physically induced pain in terms of which areas of the brain were activated. This is evidence that the brain can produce pain and that this pain is the same as physically induced pain, that is, it is real pain.
Since injury can occur without pain, and pain can occur without an injury, understanding how the brain activates pain has become an important subject. It turns out that the key to understanding pain is whether and how the subconscious parts of the brain activate the alarm or danger signal.
Kross and colleagues performed functional MRI’s in college students after a mild physical injury (an electric shock) and after viewing a picture of an ex-lover who broke up with them in the previous six months. The somatosensory cortex and dorsal posterior insula areas lit up in both conditions, suggesting that physical pain and emotional pain are similar. While being somewhat unkind in its design, this study makes this important point: rejection hurts. In a study at UCLA, Eisenberger and colleagues demonstrated that social rejection (accomplished through inclusion or exclusion while playing an interactive video game) lowered the pain threshold and activated the anterior cingulate cortex, an area correlated with the sensation of pain.
The importance of this research is to underscore two concepts. First, pain may be a response to a physical injury OR may occur in the absence of an injury. Second, events that affect the subconscious brain, such as emotional reactions, can create pain because they are linked to pain areas in the brain. I saw a patient recently who developed severe abdominal pain when her son became abusive and controlling. An extensive medical workup found no evidence of a pathological process or a structural problem. Her doctors were at a loss to explain the severe pain and she as diagnosed as having irritable bowel syndrome. However, it is surprisingly common for this scenario to occur. The pain is real, very real, yet is caused by an emotional reaction. Of course, the treatment for this condition is very different than for appendicitis or a gall bladder infection. In this case, she recovered, but only after making some significant and necessary changes in her life.
While everyone knows that physical pain can cause emotional pain, emotional pain can also cause physical pain. This becomes particularly important to recognize in the setting of chronic, medically unexplained pain syndromes. Understanding this simple fact will help doctors and patients get to the root cause of suffering for a large number of people who have chronic pain that has been unexplained medically. My next blog will explore how acute pain can turn into chronic pain.
To your health,
Howard Schubiner, MD