Evaluation Through Transcutaneous Tissue Oximetry (Near Infrared Spectroscopy) of Spinal Cord Stimulation in Patients With Complex Regional Pain Syndrome Type I.

Objective: One of the physiopathological hypothesis behind complex regional pain syndrome (CRPS) type I involves the deep-tissue hypoxia of the affected areas. Spinal cord stimulation (SCS) appears to be effective in the treatment of these patients. We evaluated whether ESCS modifies tissue oxygen saturation (StO ) measured with near-infrared spectroscopy (NIRS) in the affected limbs in patients diagnosed with CRPS type I.

Materials And Methods: Nonrandomized, cross-sectional study that evaluated 16 patients with CRPS type I who were receiving SCS applied to the posterior cords. NIRS was used to evaluate baseline StO (primary outcome) and variations in StO (secondary outcome) during an ischemia-reperfusion test performed using a vascular occlusion test, comparing the hands of limbs unilaterally affected by CRPS type I with the unaffected contralateral hands. We also determined whether the variations in StO were related to a modification in the percentage of subjective pain improvement and in the visual analog scale score.

Results: The baseline StO of the affected hands was significantly higher than that of the unaffected hands (mean 4.7%; 95% confidence interval: 1.41, 6.7; p = 0.005). Variations in StO during the ischemia-reperfusion test revealed no differences between affected and unaffected hands. No significant correlations were detected between baseline StO values or variations in StO during the vascular occlusion test and the pain measurements.

Conclusions: Baseline StO evaluated by NIRS was greater in the affected hands of patients with CRPS type I treated with SCS than in the unaffected, contralateral hands.