Category: Tremor
Objective: To investigate neural mechanisms underlying motor imagination (MI) in essential tremor (ET) patients compared to healthy controls using high-density EEG.
Background: ET ranges among the most common movement disorders and is characterized by action and postural tremor. A growing body of literature suggests aberrant cerebello-thalamo-cortical coupling. MI tasks are associated with involvement of cortical and cerebellar pathways and specifically with modulation of the beta frequency band in the sensorimotor system1,2. And although impairment of MI has been described in ET patients3 underlying neurophysiological processes remain to be elucidated and particularly with respect to MI of tremulous movements.
Method: 23 ET patients and 22 matched healthy controls were asked to imagine tremulous movements of the right hand during high-density EEG recordings. Of these, 32 subjects received 3T structural MRI. Following standard preprocessing, time-frequency analyses with multiple tapers were performed using the Fieldtrip toolbox. Time-frequency representations within the beta frequency band where compared between MI of tremor and resting-state using cluster-based permutation testing in an ANOVA-like (2 x 2) design. The resulting sensor-level clusters were finally subjected to source analysis using a Dynamical Imaging of Coherent Sources (DICS) beamformer approach in the frequency domain.
Results: Permutation tests between ET and healthy controls revealed significant differences in beta band power during MI of tremor (p=0.05). Resulting clusters projected mainly to bilateral frontal and to left parietotemporal regions. Beamforming then identified the source of the higher beta-band power in the bilateral left-dominant lateral part of the motor cortex and in parts of the left dorsolateral prefrontal cortex.
Conclusion: We could show differences within MI tasks of tremulous movements between ET-patients and healthy control subjects with the former showing stronger and earlier re-occurrence of beta activity. Interestingly, this finding was related to cortical dysfunction with a maximum in the contralateral frontal cortex, as fundamental part of the cerebello-thalamo-cortical pathway during tremor generation. Taken together, our findings support the notion of impaired neural coupling in cortical structures in ET that affects MI of tremor.
References: 1. Schnitzler A, Salenius S, Salmelin R, Jousmäki V, Hari R. Involvement of primary motor cortex in motor imagery: A neuromagnetic study. Neuroimage. 1997;6(3):201-208. doi:10.1006/nimg.1997.0286
2. Pfurtscheller G, Neuper C. Motor imagery activates primary sensorimotor area in humans. Neurosci Lett. 1997;239(2-3):65-68. doi:10.1016/S0304-3940(97)00889-6
3. Lo YN, Louis ED, Fook-Chong S, Tan EK. Impaired motor imagery in patients with essential tremor: A case control study. Mov Disord. 2007;22(4):504-508. doi:10.1002/mds.21356
To cite this abstract in AMA style:
K. Steidel, A R. Abou Watfa, C. Nelles, E. Pelzer, M. Tittgemeyer, L. Timmermann, DJ. Pedrosa. Impaired Imagery of Tremor in Patients with Essential Tremor [abstract]. Mov Disord. 2022; 37 (suppl 2). https://www.mdsabstracts.org/abstract/impaired-imagery-of-tremor-in-patients-with-essential-tremor/. Accessed November 3, 2024.« Back to 2022 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/impaired-imagery-of-tremor-in-patients-with-essential-tremor/