Patient Selection and Implantable Technology: Making Appropriate Recommendations

Insurance limitations in the private sector do not allow me the luxury of administering an extensive psychological test battery. My recommendations are now based on experience, observation, and the patient's history. Over the past 15 years, I have evaluated approximately 5000 pain patients with over 1000 of them referred for implantable technology. If a patient tells me their pain is 10/10 or 15/10 on a 10-point scale, they are revealing important information relevant to their perception of their pain. Further, if they tell me their pain is unbearable or intense, they are more than likely magnifying or over-interpreting their symptomatology.

Both of these pieces of information contribute to an additive process that culminates in a recommendation that in part, shapes the patient's treatment plan. My experience would tell me that both of these factors would contribute to the cognitive component of the model I described earlier. The catastrophic patient is difficult to treat since they are consistently inflating pain reports that will influence the outcome of the treatment plan. Further, we now know that catastrophizing has a physiological component that contributes to the patient's level of arousal or sympathetic nervous system reactivity. Therefore, we now have a direct link from the psychological to the physical aspects of pain with both neocortical and biochemical additive influences contributing to the perception of pain.

Recent experience in the private sector encourages me to be more adaptable and use information that is available at the time of the initial review. If my initial clinical impression is not obvious, I will schedule subsequent sessions to explore additional, relevant history and add more behavioral observation. My focus during the interview is to look for signs and symptoms of cognitive and affective contributions that would contribute to a negative outcome.

One cognitive area that I explore in depth with the patient is their expectations and are they realistic. If the patient is looking for a cure or to be fixed, the implantable technology may not be appropriate at this time. If the patient is motivated and open to a brief therapeutic experience, I would recommend delaying the trial until we have completed an additional four to six sessions.

I also try to see the patient during the trial period or shortly after trial before implantation. This is a critical moment to check the patient's expectations as compared to their expectations prior to the trial. If the expectations do not reasonably match, implantation should be delayed or reconsidered. Unrealistic expectations are a critical cognitive component that should be assessed before the trial, during the trials, and after the trial is completed.

I recommend that the implanting physician consider not only sensory symptomatology, but to also consider cognitive and affective symptoms when evaluating the patient for implantable pain technology. I further recommend that the implanting physician consider all the psychological or functional overlay the patient presents. Research would suggest that approximately 80% of all outpatient chronic pain patients exhibit clinical levels of psychological overlay. Therefore, the implanting physician needs to incorporate multiple sources of information and then utilize this information in their decision making algorithm. Ultimately, it is not an either or proposition, but a continuum of psychological severity or distress that the patient presents throughout the selection process. If the patient's level of distress is significant and not consistent or out of proportion to physical findings, then caution is warranted.

Recommended Resources
I recommend the following resources that discuss in more depth the reasoning that has been presented in this paper.

1. For general background, Howard Field's red book on pain, and Melzack and Wall's textbook on pain are invaluable.

2. Dennis Turk and Ron Melzack's Handbook of Pain Assessment, Second Edition is an excellent resource.

3. Robert Gatchel and Dennis Turk's two books Psychological Approaches to Pain Management and Psychosocial Factors in Pain are informative resources that I have found to be very helpful.

4. The research I conducted at OHSU was published in the inaugural issue of Neuromodulation, Vol. 1, Number 1. This study discusses the role of psychological factors and spinal cord stimulation trial outcome. The bibliography is very extensive and represents an excellent review of the literature. A subsequent study published in the Journal of Neurosurgery (1995), was conducted in collaboration with Kim Burchiel and included results post-implantation. Dan Doleys and I published a monograph on patient selection and psychological variables available through Medtronic, Inc.

5. William Livingston's book Pain and Suffering published by the ISAP.

Conclusion
Finally, I hope this review has provided the reader with a valuable overview of my personal odyssey in evaluating pain patients for implantable pain technology. Further, in my opinion, the above patient selection principles apply to all pain patients considered for elective surgery.