Patient Selection and Implantable Technology: Elective Surgery for Chronic Pain - Taking it Up a Notch

In the early days, we worked as a team with Anesthesiology involved in the early part of the process, namely patient selection. We divided patient selection into two parts; physical and psychological. At that time, I did not conceptualize the two parts as mutually exclusive, but complementary to each other; somehow hooked together and equally important. Recent Positron Emission Tomography (PET) research involving pain has confirmed my thinking. The neocortex does influence the pain process that includes the perception and subsequent expression of the nociceptive stimulus.

The work of Melzack and Wall also contributed to my early conceptualization of the pain process. They proposed that higher mental processes or what they called motivational influences contributed to the perception of pain.

Pain Model
Melzack's interactive model of pain formed the basis for my early work on the psychological aspects of patient selection. Melzack's model included three main components: sensory, affective, and evaluative or cognitive. Each of the components is proposed to work together in relative or additive concert to describe the pain experience. I base my psychological evaluation on these three components. Each patient referred for implantable pain technology underwent an extensive psychological evaluation.

Affective and Cognitive Factors
My initial premise was that the more affective and cognitive factors that could be identified, the more likely a negative outcome would be experienced. We then initiated a series of research projects starting with spinal cord stimulation trial outcomes, progressing to outcomes post-implantation. The results of these early research projects suggested that depression (affective) and catastrophic thinking (cognitive) contributed to negative outcomes. Subsequent factor analyses also suggested that age and male gender may contribute to negative outcomes. It is interesting to note that other independent research looking at outcome with pain patients in behavioral treatment programs have also identified the above factors as contributing to negative outcomes (Turk and Gatchel).

Gate Control Model of Pain
The cumulative work of Melzack and Wall together and individually is still with us, even with the recent, untimely passing of Patrick Wall. Both writers updated their thinking regarding the Gate Control Model of Pain in the American Pain Society (APS) Pain Journal Forum. As a lasting testimony to the impact of the Gate Control Mode, over 2000 published research projects can be directly attributed to the Gate Control Model of Pain.

History: Psychological Factors in Pain Expression
Historically, William Livingston was a prominent surgeon and early pain researcher whose work was overlooked until the International Association for the Study of Pain (IASP) funded the publication of his book, Pain and Suffering. Dr. Livingston's work and research played an important role in the development of Melzack's model of pain.

After WWII, Dr. Livingston founded the first Academic Medical Pain Center in the U.S. at the University of Oregon Medical School, now called Oregon Health Sciences University. At that time, Dr. Livingston was Chairman of the Department of Surgery. As early as 1938, he talked about the importance of psychological factors in the expression of pain.

In the 1950's he accepted a young researcher, a psychologist to join his pain clinic as a fellow. The psychologist's name was Ron Melzack. It is interesting to speculate what influence Livingston had in the development of Melzack's work and subsequently in the Gate Control Model of Pain. I still feel honored to have contributed a small part to the long tradition started by William Livingston at the University of Oregon Medical School.