Objective: To investigate differences in motor cortex compensation across Parkinson’s disease (PD) patients with different putamen neurodegeneration laterality.

Background: Abnormalities in the putamen–motor cortex (M1) circuitry are observed in PD, but their role in progression is unclear. It’s debated whether cortical changes drive symptoms or compensate for neurodegeneration. Most studies overlook striatal neurodegeneration laterality subtypes, which could reveal deeper insights into motor cortex compensation.

Method: Forty-five patients with mild PD were included. [¹⁸F]FDOPA_PET/CT was used to assess striatal dopaminergic degeneration, classifying patients into three groups based on the posterior putamen uptake ratio: (i) bilateral putamen involvement (PD_BI), (ii) predominant left putamen involvement (PD_L), and (iii) predominant right putamen involvement (PD_R). Electroencephalography (EEG) was used to assess M1 activity, with signals recorded during motor tasks and resting periods to evaluate, in the beta-gamma range, the event-related desynchronization (ERD) and event-related synchronization (ERS), respectively. Motor dysfunction was evaluated using the Unified Parkinson’s Disease Rating Scale (UPDRS). Based on [¹⁸F]FDOPA_PET/CT and EEG results, we formulated the Motor Cortex Compensation Coefficient (MCC), as a logarithmic ratio of ERS in M1 to [¹⁸F]FDOPA_PET/CT posterior putamen uptake. A higher MCC reflects greater cortical involvement, potentially indicating compensatory mechanisms in response to dopamine deficits.

Results: Although the PD_BI had the lowest mean value of [¹⁸F]FDOPA_PET/CT in the posterior putamen, no significant differences were found between the groups. However, ERS in M1 was significantly higher in the PD_BI and P_L groups compared to the PD_R group. MCC was greater in the PD_BI than in the PD_R group, but in the PD_BI group, MCC did not correlate with PD symptoms (UPDRS). In contrast, MCC showed a positive correlation with UPDRS Part III for the affected hand in the PD_L, and a negative correlation in the PD_R.

Conclusion: Our findings suggest that motor cortex activity varies with the lateralization of putamen neurodegeneration. Distinct compensation patterns across the PD subtypes indicate that the nature of motor cortex compensation may be shaped by the laterality of dopaminergic degeneration.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/differential-motor-cortex-compensation-in-parkinsons-disease-based-on-putamen-neurodegeneration-laterality-insights-from-eeg-and-%c2%b9%e2%81%b8ffdopa-pet-ct/