B. M. de Jong

Disease progression continues in patients with advanced Parkinson's disease and effective subthalamic nucleus stimulation

Objectives: Glutamate mediated excitotoxicity of the hyperactive subthalamic nucleus (STN) has been reported to contribute to nigral degeneration in Parkinson’s disease (PD). Deep brain stimulation of the STN (STN DBS), in its role as a highly effective treatment of severe PD motor complications, has been thought to inhibit STN hyperactivity and therefore decrease progression of PD. Methods: In a prospective two centre study, disease progression was determined by means of serial 18F-fluorodopa (F-dopa) positron emission tomography (PET) in 30 patients with successful STN DBS over the first 16 (SD 6) months after surgery. Results: Depending on the method of PET data analysis used in the two centres, annual progression rates relative to baseline were 9.5–12.4% in the caudate and 10.7–12.9% in the putamen. Conclusions: This functional imaging study is the first to demonstrate a continuous decline of dopaminergic function in patients with advanced PD under clinically effective bilateral STN stimulation. The rates of progression in patients with STN DBS were within the range of previously reported data from longitudinal imaging studies in PD. Therefore this study could not confirm the neuroprotective properties of DBS in the STN target.

Muscle co-activity tuning in Parkinsonian hand movement: disease-specific changes at behavioral and cerebral level

We investigated simple directional hand movements based on different degrees of muscle co-activity, at behavioral and cerebral level in healthy subjects and Parkinsons disease (PD) patients. We compared “singular” movements, dominated by the activity of one agonist muscle, to “composite” movements, requiring conjoint activity of multiple muscles, in a center-out (right hand) step-tracking task. Behavioral parameters were obtained by EMG and kinematic recordings. fMRI was used to investigate differences in underlying brain activations between PD patients (N = 12) and healthy (age-matched) subjects (N = 18). In healthy subjects, composite movements recruited the striatum and cortical areas comprising bilaterally the supplementary motor area and premotor cortex, contralateral medial prefrontal cortex, primary motor cortex, primary visual cortex, and ipsilateral superior parietal cortex. Contrarily, the ipsilateral cerebellum was more involved in singular movements. This striking dichotomy between striatal and cortical recruitment vs. cerebellar involvement was considered to reflect the complementary roles of these areas in motor control, in which the basal ganglia are involved in movement selection and the cerebellum in movement optimization. Compared to healthy subjects, PD patients showed decreased activation of the striatum and cortical areas in composite movement, while performing worse at behavioral level. This implies that PD patients are especially impaired on tasks requiring highly tuned muscle co-activity. Singular movement, on the other hand, was characterized by a combination of increased activation of the ipsilateral parietal cortex and left cerebellum. As singular movement performance was only slightly compromised, we interpret this as a reflection of increased visuospatial processing, possibly as a compensational mechanism.

Initiation and inhibition of wrist movements in parkinson patients and healthy controls

This paper discusses Initiation and inhibition of wrist movements in parkinson patients and healthy controls. It was presented at the Fourteenth International Congress of Parkinsons Disease and Movement Disorders.

Patients with Parkinson's disease have a less differentiated muscle activation pattern than healthy controls during manual circle movement

This paper discusses Initiation and inhibition of wrist movements in parkinson patients and healthy controls. It was presented at the Fourteenth International Congress of Parkinsons Disease and Movement Disorders.

P5-9 Evidence from EMG and kinematics for detoriated muscle activation patterns during manual circle movement in patients with Parkinson's disease

normal control (CTL); any subject who had an mUPDRS rating scale of 1 was classified as MPS-mild; and any subject who had any an mUPDRS rating of 2 or higher was classified as MPS-severe. In order to measure physical activity in daily life, subjects wore an Actiwatch® on their non-dominant hand for one week, resulting in a measure of activity counts (AC). Results: Of the 714 participants with complete data, 114 subjects (16.0%) were classified as MPS-mild and 46 subjects (6.4%) as MPS-severe. Our measure of AC was 31.2±11.2 (mean ±SD, ×104) in the CTL group, 31.6±12.0 in the MPS-mild group, and 20.8±10.9 in the MPS-severe group. While there was no significant difference in AC between the CTL and MPSmild groups, AC was lower in the MPS-severe group compared with both the CTL and the MPS-mild groups. Diagnostic sensitivity of MPS-severe became 100% when we adopted a cutoff point of low physical activity, as measured by actigraphy, combined with the presence of subjective depression by GDS. Conclusion: Actigraphy may be a useful objective tool for screening MPS, especially MPS-severe.