Platform Session – NIBS: Cerebellar direct current stimulation (tDCS) for the treatment of phantom limb pain (PLP)

Abstract

Introduction Non-invasive brain stimulation techniques, as repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS), have recently emerged as promising tools for modulating pain experience in humans. In previous studies, we have proved that cerebellar tDCS modulates nociceptive processing and pain perception, suggesting that cerebellum is strongly engaged in the sensory-discriminative, as well as in the affective/emotional and cognitive dimensions of pain. The primary aim of this study is to evaluate the possibility to modulate nociceptive processing and pain perception with cerebellar tDCS in patients suffering from phantom limb pain (PLP). Methods Eight patients underwent cerebellar tDCS (anodal or sham, 2.0 mA, 20’ per day, five days a week). Inclusion criteria are: (1) age older than 18 years; (2) unilateral lower limb amputation; (3) average pain of at least 4 on a numeric rating scale; and (4) any medications dosages stable for at least two weeks prior the study. Clinical scores and electrophysiological parameters were assessed before tDCS, at the end of 5-days treatment, two weeks and one month after tDCS completion. Changes in Visual Analogue Scores (VAS) was evaluated (chronic pain, paroxysmal pain, stump pain, telescoping, phantom movements). LEPs were obtained using a Nd:YAP laser (wavelength 1.04 μ m, pulse 164 duration 2–20 ms, maximum energy 7 J). The amputated limb was stimulated by laser pulses with short duration (5 ms) and small diameter spots (5 mm). HADS, SF-36 and BPI were administered to each patient, in order to evaluate the effect of PLP on psychological well-being, daily living and the efficacy of the treatment to improve quality of life and reduce pain perception. Results Anodal tcDCS significantly reduced non painful phantom limb sensations (p Conclusion Anodal tcDCS significantly improves both painful and non painful phantom limb sensations, which are induced by maladaptive changes in the sensorimotor network and posterior parietal cortex respectively. Cerebellar polarization may ultimately restore this connectivity, as tcDCS may act not only on spinal nociceptive neurons, but also on wide-range cortical networks of the pain matrix, thus influencing LEPs and pain experience through top-down and bottom-up mechanisms.