Evaluation of the chronic low back pain patient: Conceptual and clinical considerations

Abstract

The purpose of this article is to provide a comprehensive review of the surprising and substantial breadth of currently available biomedical, physiological, and psychometric assessment methods for chronic low back pain (CLBP). Biomedical methods such as nuclear magnetic resonance may so revolutionize medical diagnosis that cases previously assumed to have psychogenic etiology may in fact be found to have been caused by spinal degenerative conditions, nerve compression, or spinal stenosis. The reviewers suggested that the traditional psychometric instrument, the MMPI, may be of dubious value in making treatment relevant diagnoses, in discriminating between organic and psychogenic etiologies, and in the prediction of treatment outcome. Several recent approaches in admittedly early stages of development seem to offer substantially more promise. To measure dimensions of cognition that may be important, investigators have assessed the kinds of coping styles patients employ to deal with pain and the attitude dimensions that may be affected by the chronic pain experience. The measurement of sensory, affective, and evaluative pain dimensions has been achieved via the McGill Pain Questionnaire, though a simple self-rating of pain intensity along a 100mm line may turn out to be just as useful clinically. Psychophysical scaling methods appear to be the most innovative to date, and quantify pain descriptors in terms of a patient's idiographic physiological response. Attempts to isolate physiological markers of chronic pain have been disappointing, but recent work suggests that the difference between right and left paraspinal EMG may be of diagnostic value in CLBP. Direct measures of pain behavior show great promise and include measurement of pain medication intake, “up time,” verbal complaints, and observer ratings of the frequency of grimacing, bracing and guarded movements. The construct validity of such behavioral measures has been demonstrated by successfully relating them to medical status variables (i.e., lumbar spine mobility limitation, hypalgesia). The authors conclude that further attempts to demonstrate the psychological involvement of the CLBP patient are redundant, and suggest that a multidimensional assessment strategy across physiological, cognitive, and behavioral domains may soon provide a treatment-relevant diagnostic and prognostic schema.