Wisdom Wednesday: Chronic Pain Syndrome

Chronic pain syndrome (CPS) is a common problem that presents a major challenge to health-care providers because of its complex natural history, unclear etiology, and poor response to therapy. CPS is a poorly defined condition. Most authors consider ongoing pain lasting longer than 6 months as diagnostic, and others have used 3 months as the minimum criterion. In chronic pain, the duration parameter is used arbitrarily. Some authors suggest that any pain that persists longer than the reasonably expected healing time for the involved tissues should be considered chronic pain. Approximately 35% of Americans have some element of chronic pain, and approximately 50 million Americans are disabled partially or totally due to chronic pain. Chronic pain is reported more commonly in women.

CPS can affect patients in various ways. Major effects in the patient's life are depressed mood, poor-quality or nonrestorative sleep, fatigue, reduced activity and libido, excessive use of drugs and alcohol, dependent behavior, and disability out of proportion with impairment. Chronic pain may lead to prolonged physical suffering, marital or family problems, loss of employment, and various adverse medical reactions from long-term therapy. Parental chronic pain increases the risk of internalizing symptoms, including anxiety and depression, in adolescents.

The pathophysiology of chronic pain syndrome (CPS) is multifactorial and complex and still is poorly understood. Some authors have suggested that CPS might be a learned behavioral syndrome that begins with a noxious stimulus that causes pain. This pain behavior then is rewarded externally or internally. Thus, this pain behavior is reinforced, and then it occurs without any noxious stimulus.

A literature review by Gupta et al indicated that in chronic pain patients, primary sensorimotor structural and functional changes are more prominent in females than in males. Males and females differed with regard to the nature and degree of insula changes (with males showing greater insula reactivity), as well as in the extent of anterior cingulate structural changes and in reactivity to emotional arousal.



My Take:
In 2016 the first definitive study on chronic pain was published as a result of national concerns of opioid addition. This study was conducted in Sweden, as the U.S. is only recently acknowledged the damage caused to our society by prescription drug addiction.

The definition is chronic pain syndrome is no longer ill defined. It is pain that is present at least 50% of the time and lasting more than six months. There are two ICDA 10 diagnostic codes that have been assigned to this diagnosis - E89.1 Chronic Pain Syndrome and E89.2 High Impact Chronic Pain Syndrome. The latter is used when the condition results in a patient that can no longer function in their normal capacity. This is, as the NIH report infers, is related more to the patient’s support system than the actual injury.

However, in both cases, the injuries create damage in the limbic system of the brain that can be seen on MR imaging. The limbic system has no clear anatomic boundaries. A distinguishing characteristic of the limbic region is that it is highly interconnected and appears to form the only major route for information transfer between the neocortex and hypothalamus.

This damage is thought to be permanent so most care is palliative in nature. One theory suggests that chemical toxins in the vagus nerve travel up to the brain from the gut damaging the limbic system.

Bottom Line:
A large percentage of my practice is dedicated to treating chronic pain syndrome. We evaluate and treat the limbic system using function neurology as outlined in Quintessential Applications as developed and taught by Dr. Walter Schmitt. I have seen remarkable recovery in some cases and hope to be able to demonstrate this on MR imaging in the near future.

Source: November 18, 2018 NIH