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High frequency somatosensory stimulation in dystonia: Evidence fordefective inhibitory plasticity
Author(s) -
Erro Roberto,
Rocchi Lorenzo,
Antelmi Elena,
Liguori Rocco,
Tinazzi Michele,
Berardelli Alfredo,
Rothwell John,
Bhatia Kailash P.
Publication year - 2018
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.27470
Subject(s) - somatosensory system , neuroscience , cervical dystonia , stimulation , somatosensory evoked potential , sensory system , sensory stimulation therapy , psychology , dystonia , neuroplasticity , sensory processing , inhibitory postsynaptic potential , electrophysiology , medicine
ABSTRACT Background Apart from motor symptoms, multiple deficits of sensory processing have been demonstrated in dystonia. The most consistent behavioural measure of this is abnormal somatosensory temporal discrimination threshold, which has recently been associated with physiological measures of reduced inhibition within the primary somatosensory area. High‐frequency repetitive sensory stimulation is a patterned electric stimulation applied to the skin through surface electrodes that has been recently reported to shorten somatosensory temporal discrimination in healthy subjects and to increase the resting level of excitability in several different types of inhibitory interaction in the somatosensory and even motor areas. Objectives We tested whether high‐frequency repetitive sensory stimulation could augment cortical inhibition and, in turn, ameliorate somatosensory temporal discrimination in cervical dystonia. Methods Somatosensory temporal discrimination and a number of electrophysiological measures of sensorimotor inhibition and facilitation were measured before and after 45 minutes of high‐frequency repetitive sensory stimulation. Results As compared with a group of healthy volunteers of similar age, in whom high‐frequency repetitive sensory stimulation increased inhibition and shortened somatosensory temporal discrimination, patients with cervical dystonia showed a consistent, paradoxical response: they had reduced suppression of paired‐pulse somatosensory evoked potentials, as well as reduced high‐frequency oscillations, lateral inhibition, and short interval intracortical inhibition. Somatosensory temporal discrimination deteriorated after the stimulation protocol, and correlated with reduced measures of inhibition within the primary somatosensory cortex. Conclusions We suggest that patients with dystonia have abnormal homeostatic inhibitory plasticity within the sensorimotor cortex and that this is responsible for their paradoxical response to high‐frequency repetitive sensory stimulation. © 2018 International Parkinson and Movement Disorder Society