Functional determinants of Parkinson's bradykinesia.

Roosma, E. (2014) Functional determinants of Parkinson's bradykinesia. thesis, Medicine.

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Abstract

Objective: Parkinson’s disease (PD) is associated with impaired visuomotor integration, which may result from disturbed feed-forward based neural processing. Therefore, we hypothesized that the magnitude of the flash-lag effect, a visual illusion which might be caused by feed-forward processing, is smaller in PD patients than in healthy controls. Furthermore, we investigated whether the magnitude of the flash-lag effect is correlated with the degree of bradykinesia. To validate the sensor recordings, we correlated the recordings with a clinical rating scale. In the present study, we also investigated whether the dominant EEG background frequency is correlated with bradykinesia. Method: Fourteen PD patients and six healthy controls were included in this prospective study. The magnitude of the flash-lag effect was determined with a psychophysical experiment in which subjects had to indicate whether they perceived a flash above or below a moving object presented on a screen. If subjects perceived the flash-lag effect, they would perceive the flash more often above the moving object (lagging behind). For the PD and the control group, we calculated the point of subjective equality (PSE), the point at which 50% of the stimuli was judged as ‘flash seen above moving object’ and 50% was judged as ‘flash seen below moving object’. The PSE represents the magnitude of the flash-lag effect. To evaluate bradykinesia, we recorded three movements using movement sensors and assessed the motor symptoms, including bradykinesia, with the Movement Disorder Society - Unified Parkinson’s Disease Rating Scale III (MDS-UPDRSIII). EEG background frequency was obtained from Fast Fourier Transformation (FFT). Results: Our study revealed that the magnitude of the flash-lag effect was smaller in PD patients than in healthy controls (p = 0.003). There was, however, no correlation with clinically assessed bradykinesia nor with bradykinesia assessed with movement sensors. Movement sensor recordings showed that the movements of patients were slower in frequency and/or smaller in amplitude in comparison with the movements of healthy controls (p = 0.031). However, no correlations between the sensor recordings and the (bradykinesia items of the) MDS-UPDRSIII were found. Furthermore, we did not find a correlation between the dominant EEG background frequency and bradykinesia. Conclusion: The present study showed a decreased flash-lag in PD patients. Although this is consistent with disturbed feed-forward based processing in PD, an expected relationship with bradykinesia was not established. Movement sensors might be useful in objectively measuring bradykinesia, but its eventual value needs to be established by comparisons with more MDS-UPDRSIII assessors of the same patients. Our study did not show a slowing in background frequency in PD patients and a relation with bradykinesia.

Item Type:	Thesis (Thesis)
Supervisor name:	Jong, Dr. B.M. De and Beudel, Dr. M.
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 11:05
Last Modified:	25 Jun 2020 11:05
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/2486

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