Psychological and behavioral factors have long been understood to be important in assessing the suitability of patients for implantable devices. In the management of chronic pain patients, spinal cord stimulators, morphine pumps and other devices have been used to alleviate unremitting pain, to increase functional ability, and to allow patients to discontinue or limit the chronic use of narcotic medication. However, selecting appropriate patients for the use of such devices is an important process and needs to be better understood.
Behavioral and psychological factors clearly have been found relevant in excluding individuals. Although high success rates, often 60 to 80 percent, are reported in utilizing spinal cord stimulators for the relief of chronic back pain, these numbers usually represent the population of psychologically screened patients. That is, this group represents the absolute best candidates for further medical intervention. Thus, even among the candidates who have already been determined to be most suitable, only 60 to 80 percent benefit. Thus, psychological evaluations for determining suitability of an implantable device such as spinal cord stimulator provide physicians assistance in determining and understanding the possible outcome prior to implanting the device itself.
The December 1996 issue of Pain Forum focused on the issue of determining the psychological suitability of implantable devices. Multiple factors have been found to be relevant in determining which individuals should be considered and which should not. The exclusionary screening criteria identified by Nelson, et al, (1996) identifies the psychological-behavioral features that should be evaluated to assess a patient's qualification. While the screening criteria do not represent a perfect algorithm for determining psychological suitability for implantable devices, it represents the best model to identify those factors which are most relevant in determining which patients will benefit from this type of treatment.
The factors utilized to assess spinal cord stimulator patients include psychological and behavioral features. Often psychological testing and a review of medical records are necessary to fully understand factors related to a person's response to pain. Moreover, some patients make an attempt to present as highly desirable in an effort to influence the physician about the need for such an intervention. In addition, the presence of litigation either in the form of Worker's Compensation or personal injury claims can also influence an individual's desire for such devices.
An appropriate psychological examination will consider several factors. First, the psychological stability of the patient, or the role of psychosis or other serious mental illness, needs to be assessed. A psychologically troubled individual can have a pain condition as real as that of anyone else. However, if a psychological illness, particularly a psychotic condition, is significant, it will increase the likelihood of highly focused somatic preoccupations. Consequently, success of a spinal cord stimulator in such a case is extremely remote. Moreover, actively suicidal or homicidal patients are poor candidates as their impulsiveness and emotional disturbance will obviously affect their thinking and ability to be stabilized by such an intervention. In addition, patients with poorly treated major depression or other mood disturbances are also contraindicated. Often providing treatment to stabilize the mood disorder is necessary prior to proceeding with invasive medical care. That is, moderate to severe depression should first be treated with medication and psychotherapy.
The presence of a somatization disorder or other somatoform pain disorder involving vague physical complaints that do not seem to correlate with organic findings is also considered one of the exclusionary criteria, especially with chronic pain patients. This particular feature needs to be carefully examined as some amount of somatization is common and should be expected with the chronic pain population. Nevertheless, a propensity for extreme somatization in conjunction with other factors clearly will impact the response to spinal cord stimulator implantation. Even when pain complaints can be documented and correlated with obvious physical findings, an exaggerated pain response can be found and ultimately will influence the individual's symptom perception. Obviously alcohol or drug dependency of either illegal or prescription drugs should be carefully monitored. Excessive drug seeking behavior should first be controlled prior to further consideration. Compensation or litigation should generally be resolved or at least excluded as a possible motivating factor, particularly if a decision regarding the implantation of the spinal cord stimulator is dependent on this litigation. In some cases, long term disability status or compensation issues are dependent on continued medical treatment.
Thus, a decision to proceed with spinal cord stimulator may be motivated not by a desire to manage pain more effectively but rather to maintain disability or compensation status.
A lack of appropriate social support has historically always been a critical variable in the success of chronic pain patients to better manage their condition. It is advisable to have family members or close friends be committed to the process of evaluation and treatment with the spinal cord stimulator. This aids not only in supporting the individual as he goes through the process but also in assisting with basic self-care activities that may be necessary. Finally, behavioral and cognitive deficits that compromise reasoning, judgment and memory also will interfere with the ability of the patient to adequately participate in the treatment process. The individual whose cognitive functioning has either deteriorated or is compromised by various factors will be unable to provide sufficient information to accurately assess the degree to which the procedure is suitable and helpful. Thus, valid reporting of information, particularly levels of pain or position, cannot be expected from the patient who is cognitively compromised or emotionally overwhelmed.
Understanding the role of these factors and considering each of these factors as part of exclusionary criteria aids the physician, the patient and those providing assistance to the pain patient. Moreover, decisions related to further invasive treatment are not simply based on an effort to resolve pain but rather on behavioral factors that take into account the full context of the individual's life and his response to medical treatment.