The Role Of Cross Sensitization In Chronic Pain Patients

Pain often modifies the way that the central nervous system works; a patient may actually become more sensitive and experience more pain with less and less provocation. This is referred to as “central sensitization”, as it involves changes in the central nervous system (in particular)…the brain and the spinal cord.

Sensitized patients are typically more sensitive to things that are “supposed” to hurt, as well as to ordinary pressure and “touch”. Their pain also has a tendency to echo, fading away more slowly than it would in others.

Because pain is a “warning system”, central sensitization is a disease of over-reaction to threats to the organism; a hyperactive warning system. Far too many patients end up experiencing even more pain in their quest to alleviate it.

The cross-sensitization process is an autonomous, self-sustaining feedforward loop, whereby prior exposure to one stimulus, like a drug, increases subsequent response to itself as well as a different stimulus, such as another drug, stress, or pain).

The involvement of sensitization in the pathophysiology of addiction is a matter of consensus (e.g., drug-induced locomotor effects). That said, its varying roles and correspondingly affected brain regions are defined by complementary and partially overlapping theories addressing both within-system (dopaminergic) and between-system (i.e., anti-reward) neuroadaptations.

This process plays a rather significant role in how patients experience chronic pain; particularly in regards to chronic pelvic pain. It is a clinical feature of “incentive sensitization”.

Drug-induced changes in the mesolimbic dopaminergic circuitry (like dopamine terminal fields) are responsible for assigning excessive motivational value to a particular object, relative to the emotional experience that it evokes, according to incentive sensitization theory.

A recent study that was presented at the annual American Urogynecologic Society meeting in Long Beach, California showed that nerves in a “painful organ” might leak the information to a nearby organ. Because of this, the brain is unable to determine and/or process where the message (and the pain) is originating. This is important to note, as patients are often told that there is nothing structurally wrong with their organs when they are experiencing chronic pelvic pain. In other words, this finding supports the view that inflammation in one of the pelvic organs may lead to symptoms in other organs through cross-sensitization.

Reversing the ongoing spiraling distress cycle is difficult, to say the least. Emotions and motivations are both essential to adjusting to ever-changing environmental demands.

However, a seasoned pain management professional will be able to harness their understanding of this process in order to comprehend how and why patients are experiencing pain and can subsequently select which type of therapy will best suit patients.