Chronic nonmalignant pain, persisting more than 6 months, affects 15%-30% of the United States population. The majority of chronic pain patients respond to a combination of physical modalities and non-opioid analgesics. However, approximately 20% do not derive sufficient pain relief from traditional measures (back surgery, oral drugs, etc.). An additional percentage of patients do not achieve a favorable balance between analgesia and side effects with systemic opioid therapy. For these patients, intraspinal delivery of opioids may improve pain relief, reduce suffering, and enhance quality of life and functional ability. Patient selection is a significant determinant of the success of this approach. Because pain is a biopsychosocial phenomenon, psychological and social assessment are essential along with adequate trials of opioid responsiveness. There are several valid approaches to conducting trials of intraspinal pain therapy including epidural and intrathecal trials. Other important issues concern trial length, the utility of placebo trials, and drug selection in cases where morphine alone provides insufficient analgesia.
It is known that, in spite of meeting appropriate clinical criteria for spinal cord stimulation (SCS) and having undergone flawless procedures, a significant number of patients who fail the therapy continues to exist. It is the purpose of this article to focus on the development of psychosocial indicators of success for SCS, if any. Referring to specialist literature authors present a review of what is known, what is not known, and what remains controversial on this topic. After reading this article we hope the reader will understand the importance of a psychological evaluation as part of the development of standards for identifying appropriate patients for this therapy. To improve treatment outcomes of SCS, seems to be essential to perform psychosocial evaluations on all persons clinically indicated for SCS to exclude those patients, who most probably, on a psychosocial level, will fail the procedure. To maximize treatment efficacy, authors believe spinal cord stimulation for chronic pain control must be part of a comprehensive program. An accurate preoperative psychosocial assessment and a course of psychological assistance both before and after therapy seems to be crucial for improving outcomes.
Spinal cord stimulation (SCS) has been used for more than 20 years in the treatment of diverse pain conditions. Although recent studies have identified more clearly those conditions for which SCSoffers a favorable prognosis, the identification of a patient population in whom reasonably long-term success can be expected has been difficult. In an effort to improve patient selection and increase the overall success rate of treatment, we have examined various physical, demographic, and psychosocial variables as predictors of SCS outcome. The study population consisted of 40 patients with chronic low back and/or leg pain, 85% of whom were diagnosed with failed back surgery syndrome. Medical history and demographic data were collected as part of an initial assessment along with patient responses to the Minnesota Multiphasic Personality Inventory, the visual analogue pain rating scale (VAS), the McGill Pain Questionnaire, the Oswestry Disability Questionnaire, the Beck Depression Inventory, and the Sickness Impact Profile. Treatment outcomes were examined and found to improve significantly after 3 months of stimulation. Subsequent regression analysis revealed that patient age, the Minnesota Multiphasic Personality Inventory depression subscale D, and the evaluative subscale of the McGill Pain Questionnaire (MPQe) were important predictors of posttreatment pain status. Increased patient age and D subscale scores correlated negatively with pain status, as measured by the percentage of changes in pretreatment and posttreatment VAS scores, % delta VAS. In contrast, higher MPQe correlated with improved pain status. By the use of the following equation and the definition commonly associated with SCS success (at least 50% decrease in the VAS pain level), the success or failure of 3 months of SCS was correctly predicted in 88% of the study population. Our results suggest that patient age, Minnesota Multiphasic Personality Inventory depression, and MPQe may be clinically useful in the prediction of pain status after 3 months of SCS in patients with chronic low back and/or leg pain. % delta VAS = 112.57 - 1.98 (D)-1.68 (Age) + 35.54 (MPQe).
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