Reduced areas of spontaneous neuropathic pain after spinal cord stimulation treatment.

OBJECTIVES Spinal cord stimulation (SCS) is known to be an effective treatment for a range of neuropathic pain (NeP) conditions, although further clinical evidence is required. Clinical observations suggest that 1 aspect of the treatment effect is a reduction in the area with spontaneous NeP. The aim of this study was to quantify the areas of spontaneous NeP in SCS patients and to correlate these with changes in pain intensity and quality of life. METHODS Twenty-six SCS patients with NeP rated their pain intensity on a numerical rating scale (0 to 10) and completed the SF-36 health survey. In addition, their areas of spontaneous pain were photographically documented before and during SCS treatment, and the areas were transferred to phantom drawings and digitally quantified. RESULTS Areas of spontaneous NeP were reduced by 62% (interquartile range, -15 to 78). Pain intensity was reduced from 7.5 ± 1.1 before to 4.9 ± 1.7 during treatment (mean ± SD) and most domains of the SF-36 health survey also improved with SCS treatment. Using linear regression, no correlation was found between relative reduction in areas of spontaneous NeP and relative reduction in pain intensity as well as in absolute improvement in quality of life assessed by SF-36. A correlation was found between improvement in pain intensity and in quality of life. DISCUSSION The results indicate that the main impact of SCS on the patients' quality of life is not the reduction of the painful areas, but rather the reduced pain intensity in the remaining area.