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.
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.
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.
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.
*Danish Pain Research Center
Department of †Neurosurgery
§Anesthesiology, Aarhus University Hospital, Aarhus C, Denmark
K.M. designed the study, collected most of the data, analyzed the data, and prepared the first draft of the manuscript. B.M.C. collected the rest of the data. M.E.M. analyzed the photographic material. T.S.J., L.N., and J.C.S. provided clinical and scientific advice. All authors revised, contributed to, and approved the final manuscript.
The study was carried out as part of a cofinanced PhD study funded by Aarhus University, Aarhus, Denmark; St Jude Medical, Zaventem, Belgium; and the Danish Medical Research Council, Copenhagen, Denmark. K.M. and J.C.S. have received teaching fees from St Jude Medical and are paid consultants for Biolab Technology. The remaining authors declare no conflict of interest.
Reprints: Kaare Meier, MD, PhD, Danish Pain Research Center, Aarhus University Hospital, Noerrebrogade 44, Building 1A, Aarhus C DK-8000, Denmark (e-mail: email@example.com).
Received August 15, 2012
Accepted March 3, 2013