„The glasses” for pain? Sensory discrimination-training in therapy of chronic pain

Chronic pain is a treatment resistant condition and is characterized by functional and structural alterations in the central nervous system (CNS). Those changes are demonstrated by reorganization of the sensory cortex and loss of density in white and grey matter in CNS. The aim of this review was to introduce the sensory discrimination training (SDT), the new therapeutic approach, developed to reverse those changes. SDT is aimed at restoring tactile acuity through training the ability to discriminate sensory stimuli. The most often used forms of SDT are tactile stimuli localization, discrimination of those stimuli and graphaestesia. Our review concentrates on theoretical assumptions underlying the SDT, the most common sensory dysfunctions associated with chronic pain (e.g. tactile acuity changes) and some of the diagnostic methods. The exemplary forms of training in phantom limb pain, complex regional pain syndrome and chronic low back pain were described. In addition, review presents critical evaluation of scientific evidence of SDT in chronic pain, including available systematic reviews and experimental studies. Scientific evidence tends to support the application of SDT in chronic pain, although unambiguous conclusions related to its effectiveness, cannot be drawn. Extensive randomized controlled trials as well as basic research are strongly advised to be conducted, as they can provide knowledge about analgesic properties of SDT in patients and healthy subjects. Quantitative synthesis of available experimental studies is also recommended.