Sensory retraining for Central Post-Stroke Pain: A subgroup analysis within a randomized controlled trial

Background: Explicit Sensory Retraining (SR) has been suggested for pain management in several neuropathic pain syndromes. Objectives: To study the effectiveness of SR on Central Post Stroke Pain (CPSP) symptoms. Methods: A preplanned subgroup of 23 subjects post-stroke reporting central pain were randomized within a larger study, to receive either explicit sensory discrimination retraining (SR) (in subgroup n = 11) or implicit repeated exposure to stimuli (RE) (in subgroup n = 12), applied to the lower limb. Pain intensity measured by VAS, measures of sensory ability; balance and gait activities; and participation were assessed by a blinded assessor at four points in time. Results: A group*time interaction effect was demonstrated (p = 0.04) for VAS, as for the SR treatment group VAS decreased from 56/100 to 23/100. Nine out of eleven subjects in the SR group demonstrated positive response to treatment. Pain alleviation was maintained at follow-up. A similar interaction effect was found for tactile threshold (p = 0.03). Significant improvement was noted for all other variables with no group differences. Conclusion: This study provides preliminary evidence to the clinically relevant positive effect of explicit sensory retraining for subjects with CPSP. The positive effect on tactile threshold detection could potentially indicate pain alleviation mechanisms.