Objective: To correlate central oscillation in the basal ganglia with EMG activity during re-emergent tremor pause.

Background: According to the dimmer-switch model, basal ganglia act as a switch, turning on and off tremor; while the cerebello-thalamo-cortical circuits act as an intensity modulator. However, there are several hypotheses as to why voluntary movement attenuates PD tremor.

Method: We performed a prospective, observational, descriptive study, on consecutive, predominantly tremorous PD patients who underwent DBS surgery. Patients presented rest tremor and had clinically defined re-emergent tremor during preoperative evaluation. Coherence analysis between GPi/STN oscillatory activity (MER) and EMG from both flexor and extensor carpi radialis muscles (FCR and ECR) during rest, posture and re-emergent tremor pause was performed during awake DBS implantation. The statistical significance level of the MER-EMG coherence was determined using a surrogate data analysis.

Results: We examined 30 consecutive patients who underwent DBS surgery. Only six of them met the inclusion criteria and were finally analyzed. We isolated 148 neurons with tremor-like activity from the 6 included patients (116 in STN, 32 in Gpi), which represented 296 correlations to be tested (MER vs each one of the simultaneous EMGs). Coherence analysis showed a significant level at tremor frequency or at first or second harmonic during rest in 135/296 cases; whereas 49/135 neurons maintained a significantly coherent activity with EMG through posture at a frequency ±1.5 Hz that of resting tremor. Finally, 26 recordings with sustained MER oscillatory activity presented significant coherence levels at tremor frequency both during rest and posture, but subthreshold levels during the pause. All 49 recordings that showed significant coherence both during rest and posture, also showed peaks at tremor frequency (± 1.5 Hz) at least two standard deviations above the mean power in the 3-10 Hz range during the pause.

Conclusion: Our results suggest that oscillatory activity in STN/GPi neurons driving tremor do not stop during re-emergent tremor pause, thus suggesting a possible primary role of the cerebello-thalamo-cortical loop in the attenuation of PD tremor during movement.

« Back to 2022 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/central-oscillation-in-the-basal-ganglia-during-re-emergent-tremor-pause-in-parkinsons-disease/