Cerebellar direct current stimulation modulates pain perception in humans

Article type: Research Article

Authors: Bocci, Tommaso^{a; b} | Santarcangelo, Enrica^c | Vannini, Beatrice^a | Torzini, Antonio^{b; d} | Carli, Giancarlo^b | Ferrucci, Roberta^e | Priori, Alberto^e | Valeriani, Massimiliano^{f; g} | Sartucci, Ferdinando^{a; d; *}

Affiliations: [a] Department of Clinical and Experimental Medicine, Unit of Neurology, Pisa University Medical School, Pisa, Italy | [b] Department of Medical and Surgical Sciences and Neuroscience, University of Siena, Siena, Italy | [c] Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy | [d] Department of Clinical and Experimental Medicine, Cisanello Neurology Unit, Pisa University Medical School, Pisa, Italy | [e] Department of Neurological Sciences, University of Milan, Fondazione IRCCS Ospedale Maggiore Policlinico, Milan, Italy | [f] Division of Neurology, Ospedale Bambino Gesù, IRCCS, Rome, Italy | [g] Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark

Correspondence: [*] Corresponding author: Prof. Ferdinando Sartucci, M.D., Associate Professor of Neurology, Pisa University Medical School, Department of Clinical and Experimental Medicine, Neurology – Neurophysiology Units, Via Roma, n. 67; I 56126 Pisa, Italy. Tel.: +39 050 992176 (direct); Fax: +39 050 550563; 992405; [email protected]

Abstract: Purpose: The cerebellum is involved in a wide number of integrative functions, but its role in pain experience and in the nociceptive information processing is poorly understood. In healthy volunteers we evaluated the effects of transcranial cerebellar direct current stimulation (tcDCS) by studying the changes in the perceptive threshold, pain intensity at given stimulation intensities (VAS:0-10) and laser evoked potentials (LEPs) variables (N1 and N2/P2 amplitudes and latencies). Methods: Fifteen subjects were studied before and after anodal, cathodal and sham tcDCS. LEPs were obtained using a neodymium:yttrium–aluminium–perovskite (Nd:YAP) laser and recorded from the dorsum of the left hand. VAS was evaluated by delivering laser pulses at two different intensities, respectively two and three times the perceptive threshold. Results: Cathodal polarization dampened significantly the perceptive threshold and increased the VAS score, while the anodal one had opposite effects. Cathodal tcDCS increased significantly the N1 and N2/P2 amplitudes and decreased their latencies, whereas anodal tcDCS elicited opposite effects. Motor thresholds assessed through transcranial magnetic stimulation were not affected by cerebellar stimulation. Conclusions: tcDCS modulates pain perception and its cortical correlates. Since it is effective on both N1 and N2/P2 components, we speculate that the cerebellum engagement in pain processing modulates the activity of both somatosensory and cingulate cortices. Present findings prompt investigation of the cerebellar direct current polarization as a possible novel and safe therapeutic tool in chronic pain patients.

Keywords: Pain cerebellum, cerebellar direct current stimulation, tDCS, laser evoked potentials, pain modulation

DOI: 10.3233/RNN-140453

Journal: Restorative Neurology and Neuroscience, vol. 33, no. 5, pp. 597-609, 2015