Visuo-Motor Coordination Deficits and Motor Impairments in Parkinson's Disease

Abstract

BackgroundVisuo-motor coordination (VMC) requires normal cognitive executive functionality, an ability to transform visual inputs into movement plans and motor-execution skills, all of which are known to be impaired in Parkinson's disease (PD). Not surprisingly, a VMC deficit in PD is well documented. Still, it is not known how this deficit relates to motor symptoms that are assessed routinely in the neurological clinic. Such relationship should reveal how particular motor dysfunctions combine with cognitive and sensory–motor impairments to produce a complex behavioral disability.Methods and FindingsThirty nine early/moderate PD patients were routinely evaluated, including motor Unified Parkinson's Disease Rating Scale (UPDRS) based assessment, A VMC testing battery in which the subjects had to track a target moving on screen along 3 different paths, and to freely trace these paths followed. Detailed kinematic analysis of tracking/tracing performance was done. Statistical analysis of the correlations between measures depicting various aspects of VMC control and UPDRS items was performed. The VMC measures which correlated most strongly with clinical symptoms represent the ability to organize tracking movements and program their direction, rather than measures representing motor-execution skills of the hand. The strong correlations of these VMC measures with total UPDRS score were weakened when the UPDRS hand-motor part was considered specifically, and were insignificant in relation to tremor of the hand. In contrast, all correlations of VMC measures with the gait/posture part of the UPDRS were found to be strongest.ConclusionsOur apparently counterintuitive findings suggest that the VMC deficit pertains more strongly to a PD related change in cognitive-executive control, than to a reduction in motor capabilities. The recently demonstrated relationship between gait/posture impairment and a cognitive decline, as found in PD, concords with this suggestion and may explain the strong correlation between VMC dysfunction and gait/posture impairment. Accordingly, we propose that what appears to reflect a motor deficit in fact represents a multisystem failure, dominated by a cognitive decline.

Is DOPA-Responsive Hypokinesia Responsible for Bimanual Coordination Deficits in Parkinson’s Disease?

“…Furthermore, PD have been shown to undershoot the amplitude of movement when they are unable to see their moving limb (61) as was the case with the augmented visual feedback used in the current study. Furthermore, PD patients have marked deficits in visuo-motor coordination that has been linked to disrupted parietal-premotor circuits (62, 63). However, augmented visual feedback led to similar impairments in coordination in PD and healthy older adults suggesting that it was not the cause of coordination deficits in PD.…”

Neuropsychologic assessment in collaborative Parkinson's disease research: A proposal from the National Institute of Neurological Disorders and Stroke Morris K. Udall Centers of Excellence for Parkinson's Disease Research at the University of Pennsylvania and the University of Washington

“…Spatial processing and concept formation are difficult to assess in patients with PD, however, given the motor component often required to complete spatial tasks. In addition, impaired executive processes may contribute to visuomotor dysfunction and make it difficult to assess pure spatial performance [85, 86]. In order to address both of these issues, we include two visuospatial measures with varying levels of motor and frontal-executive demand.…”

Do Co-Morbidities and Cognition Impact Functional Change and Discharge Needs in Parkinson Disease?

“…16,17 Cognitive impairments correlate with gait and postural function. 18 Depressive symptoms may be found in as many as 40% of PD patients and may also impact motor functioning. 19,20 In a study of 50 outpatients with idiopathic PD, depressive symptoms were noted in higher Hoehn and Yahr stages and in those with declines in functional capacity.…”