Cervical dystonia: Normal auditory mismatch negativity and abnormal somatosensory mismatch negativity

Publication date: Available online 4 July 2018
Source:Clinical Neurophysiology
Author(s): Jui-Cheng Chen, Antonella Macerollo, Anna Sadnicka, Min-Kuei Lu, Chon-Haw Tsai, Prasad Korlipara, Kailash Bhatia, John C. Rothwell, Mark J. Edwards
ObjectivePrevious electrophysiological and psychophysical tests have suggested that somatosensory integration is abnormal in dystonia. Here, we hypothesised that this abnormality could relate to a more general deficit in pre-attentive error/deviant detection in patients with dystonia. We therefore tested patients with dystonia and healthy subjects using a mismatch negativity paradigm (MMN), where evoked potentials generated in response to a standard repeated stimulus are subtracted from the responses to a rare "odd ball" stimulus.MethodsWe assessed MMN for somatosensory and auditory stimuli in patients with cervical dystonia and healthy age matched controls.ResultsWe found a significant group∗oddball type interaction effect (F (1, 34) = 4.5, p = 0.04, ρI = 0.63). A follow up independent t-test for sMMN data, showed a smaller sMMN amplitude in dystonic patients compared to controls (mean difference control-dystonia: -1.0 µV ± 0.3, p < 0.00, t = -3.1). However the amplitude of aMMN did not differ between groups (mean difference control-dystonia: -0.2 µV ± 0.2, p = 0.24, t = -1.2). We found a positive correlation between somatosensory MMN and somatosensory temporal discrimination threshold.ConclusionThese results suggest that pre-attentive error/deviant detection, specifically in the somatosensory domain, is abnormal in dystonia. This could underlie some previously reported electrophysiological and psychophysical abnormalities of somatosensory integration in dystonia.SignificanceOne could hypothesize a deficit in pre-conscious orientation towards potentially salient signals might lead to a more conservative threshold for decision-making in dystonia.



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