Objective: To compare premovement event related desynchronization (ERD) between simple lower limb movement and simulated gait initiation in Parkinson’s disease (PD) patients using Magnetoencephalography (MEG).

Background: It has been known that the beta-band (13-30Hz) desynchronization in motor-related cerebral cortex during motor preparation is modulated by the motor task. In this study, we compared premovement ERD between lower limb movement and simulated gait initiation in PD patients.

Methods: We enrolled PD patients without gait freezing, and the subjects were to take MEG on two tasks with right feet. In the first task, the task was simple ankle dorsiflexion (S(-)) similar to gait initiation, and in the second, simulated gait initiation was done with simple dorsiflexion (S(+)). Each task was examined in visual cued movement sequences independently. We performed the two tasks in medication-off state(M(-)) and medication-on state(M(+)), respectively. Gyroscope chips were attached to right toe to precisely detect movement onsets and artifacts. Visual cue was presented on the screen irregularly.

Time-frequency power plot were calculated for each tasks during the premovement period (the 2.0 seconds preceding S(-) or S(+) execution), and the corresponding beta-band ERD (beta-ERD) or beta-band synchronization (beta-ERS) power was represented. We chose the sensors near the contralateral supplementary motor, premotor and primary motor cortex.

Results: We analyzed data from 11 PD patients. During 0.6‒0.0 sec prior to the movement onset, the maximum premovement beta-ERD values were statistically different in M(+) (-65.22±30.85 % in S(-) vs. -82.36±50.71 % in S(+), P=0.04, respectively), but not in M(-) (-53.45±18.53 % in S(-) vs. -60.17 ± 29.58 % in S(+), P=0.35, respectively). Mean power of beta-ERD showed significant differences between S(-) and S(+) different in M(+) (-32.71±2.85 % in S(-) vs. -47.02±27.68 % in S(+), P=0.02) and not in M(-) (-20.50±7.16 % in S(-) vs. -25.12±10.93 % in S(+), P=0.85).

Conclusions: We found that the maximum or mean power in premovement beta-ERD activity was higher in S(+) than S(-) in the contralateral medial sensorimotor area in M(+). This result implicates that the beta-band power during premovement phase can reflect the intent of movement in PD patients in medication-on state.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/premovement-betaband-event-related-desynchronization-related-to-simple-lower-limb-movement-and-simulated-gait-initiation-in-parkinsons-disease-patients-meg-study/