Pain drawings in the assessment of nerve root compression: a comparative study with lumbar spine magnetic resonance imaging.

STUDY DESIGN

Prospective comparative study of pain drawings with findings on lumbar spine magnetic resonance imaging.

OBJECTIVES

To assess the ability of the pain drawing to predict the presence of nerve root compression.

SUMMARY OF BACKGROUND DATA

Most research work has concentrated on the ability of the pain drawing to act as a screening method for psychological distress with less work directed at the influence the anatomic abnormality has on the pain drawing.

METHODS

One hundred thirty-four consecutive outpatients attending for lumbar magnetic resonance imaging in the investigation of back and leg pain completed pain drawings and psychological testing immediately before the examination. The pain drawing was analyzed by previously reported criteria, and the magnetic resonance imaging was assessed independently for the presence of nerve compression by three radiologists. Multivariate stepwise discriminant analysis was used to identify patients with nerve compression on the basis of their pain drawing.

RESULTS

Nerve compression was predicted by numbness in the anterolateral aspect of the foot. There was considerable overlap in the appearances of the pain drawings between patients with and without nerve compression, and the pain drawing correctly classified only 58% of patients with nerve compression.

CONCLUSIONS

The pain drawing is not a good predictor of nerve compression on magnetic resonance imaging in a group of patients investigated for back and leg pain. It should be interpreted with caution and in light of the full clinical picture.