P190 Cerebellar direct current stimulation modulates pain perception in humans

Abstract

Question The cerebellum is involved in a wide number of integrative functions, but its role in pain perception and nociceptive processing is poorly understood. We evaluated the effects of transcranial cerebellar direct current stimulation (tcDCS) by studying the changes in perceptive threshold (PT), pain intensity (VAS) and laser evoked potentials (LEPs) variables (amplitude and latency of both N1 and N2/P2 responses). Methods Fifteen subjects were studied before and after anodal, cathodal and sham tcDCS. LEPs were obtained using a Nd:YAP laser (wavelength 1.04 μm, pulse 164 duration 2–20 ms, maximum energy 7 J). The laser beam was transmitted from the generator to the stimulating probe via a 10 m length optical fibre; signals were then amplified, band pass filtered (0.1–200 Hz, time analysis 1000 ms). The dorsum of the left hand was stimulated by laser pulses (individual variability: 3.89–15.75 J/cm2) with short duration (5 ms) and small diameter spots (5 mm). VAS was evaluated by delivering laser pulses at two different intensities, respectively two and three times the PT. Results Cathodal polarization dampened the PT and increased the VAS score, while the anodal one had opposite effects. Conclusions TcDCS modulates pain perception and its cortical correlates. As it is effective on N1 and N2/P2 components and these responses are generated by parallel and partially segregated spinal pathways reaching different cortical targets, we speculate that the cerebellum modulates the activity of both somatosensory and cingulate cortices, thus interfering with the sensory-discriminative and emotional dimensions of pain. Present findings prompt investigation of the tsDCS as a novel, safe therapeutic tool in chronic pain patients. Download : Download high-res image (428KB) Download : Download full-size image