Predicting outcome in the surgical treatment of lumbar radiculopathy using the Pain Drawing Score, McGill Short Form Pain Questionnaire, and risk factors including psychosocial issues and axial joint pain.

BACKGROUND: The surgical decompression of a symptomatic lumbar nerve root is generally regarded as effective treatment for radiculopathy. Nevertheless this straightforward surgical procedure is not universally successful, and the results are often independent of technical factors.

PURPOSE: To identify tools and risk factors that would permit the preoperative determination of the probability for an acceptable surgical result.

STUDY DESIGN: Prospective consecutive nonrandomized study evaluating the short-term result (average 12 months follow-up) of the surgical decompression of a single spinal nerve.

PATIENT SAMPLE: 110 adult patients who had failed conservative treatment were carefully selected after identification of predominate symptoms secondary to disc herniation, synovial cyst, or foramenal stenosis due to spondylosis.

OUTCOME MEASURES: A combination of 6 measurement tools were used: the visual analogue scale (VAS); the McGill Sensory Score; the McGill Affective Score; the Prolo Economic Score; the Prolo Functional Score; and the Modified Ransford Pain Drawing Score.

METHODS: Preoperatively and at each post-op visit the patients completed the entire battery of outcome tools. Comorbidities were identified preoperatively as risk factors. Patient assessment of outcome was determined in two ways: a 50% or greater reduction in VAS; or using a 4 step scale combining the Prolo scores. Surgeon assessment of outcome was determined subjectively using clinical criteria.

RESULTS: All 6 measurement tools showed statistically significant improvement postoperatively. The change in pain drawing score has not been previously demonstrated in the literature. Correlation testing showed association between compensation claim, psychiatric factor, and high preoperative pain drawing score on several post-op measurements. Stepwise regression analysis revealed preoperative axial joint pain to be a determinant of outcome in addition to the psychosocial issues. Although the distribution of outcome grades was different between surgeon and patient assessment, relative risk analysis showed that the factors predicting outcome were identical, and the rank order of importance in these risk factors was almost identical. Using patient assessment of outcome there was no probability of a good or excellent outcome in the presence of either psychiatric factor or personal injury claim, and only a 23% chance with a compensation case. Axial joint pain is obviously not treatable by nerve root decompression, and if present will also be an important negative risk factor, reducing the probability to 27%. The evaluation of the preoperative pain drawing using a Modified Ransford Score is not useful as a predictor of psychiatric factor nor should it be used as a substitute for psychological evaluation. Nevertheless a preoperative score >or=3 or higher reduced the probability of an excellent or good outcome (as determined by patient assessment using combined Prolo scores) to 55%. Additionally a high preoperative McGill Sensory score >or=17 or a high preoperative McGill Affective Score >or=7 also had profound negative effects, reducing the probability of acceptable outcome to 50% and 42%, respectively. These threshold values for the McGill scores correspond to one standard deviation above the normal range previously validated in the literature.

CONCLUSION: Although psychosocial issues (psychiatric factor, personal injury litigation, compensation claim) are well known to affect outcome, the strength and magnitude of their negative effects was surprising. The short form McGill Pain Questionnaire can be used not only as an outcome tool, but also as a predictor of result. The pain drawing has similar utility, but it should not be used as a substitute for psychiatric evaluation. The numerous issues exerting profound effects on the outcome of a relatively simple operation suggest that specific attention be directed at them when evaluating more complex surgical procedures. Although large randomized samples might obviate this concern, it is possible that some of these factors are too powerful to be ignored.