Anticipatory postural adjustments during self inflicted and predictable perturbations in Parkinson's disease.

Abstract

This study investigated the relation between impaired anticipatory postural adjustments and bradykinesia in Parkinson's disease. Patients with Parkinson's disease and age matched controls stood on a platform. In one series of experiments, they performed fast, discrete shoulder flexion or extension movements. In another series, they were required to press a trigger with the right thumb and thus to release a load that was suspended from a bar which they were holding in front of them in extended arms. One more series included catching a load on the same bar. Anticipatory changes in the activity of postural muscles before fast voluntary movements occurred in patients and controls although the patients showed higher variability of anticipatory patterns. During load dropping and catching, control subjects had reproducible, although smaller, anticipatory changes in postural muscle activity. Such changes were absent in all but one patient. Two sources of these postural perturbations were analysed. The anticipatory postural adjustments in different muscle groups may counteract perturbations of different origin. The distal to proximal sequencing of joint involvement in postural reactions may be related to different reference points and working points associated with these tasks compared with reaching limb movements. The deficit in anticipatory postural adjustments in Parkinson's disease is likely to be unrelated to bradykinesia and is more likely to reflect the deficits in the basic processes of preparation and initiation of a motor act. (J Neurol Neurosurg Psychiatry 1995;58:326-334)

Postural control during a sit-to-stand task in individuals with mild Parkinson's disease

“…This hypothesis was based on clinical speculation (Morris 2000;Morris et al, 1997), in addition to the literature which has demonstrated impaired anticipatory postural control during arm movements while standing in PD subjects (Latash et al 1994;Rogers et al 1987;Traub et al 1980). Furthermore, several studies have shown altered function of the supplementary motor area in PD due to its indirect connections with the basal ganglia (Cunnington et al 1996;Grafton et al 1995).…”

“…It has been speculated that the inability to rise from a chair in persons with PD may be a result of altered anticipatory postural control and consequently a failure to bring the COM adequately forward over the feet prior to the lift-off of the buttocks from the chair (Morris 2000;Morris et al 1997). Such hypotheses have been fueled by reports of altered anticipatory postural control during tasks such as arm movements while standing in PD subjects (Latash et al 1994;Rogers et al 1987;Traub et al 1980), in addition to altered supplementary motor area function in PD, which has been linked to the performance of preparatory postural control during tasks such as finger movements (Cunnington et al 1996). However, no study has yet quantified the movement strategies used by individuals with PD to rise from a chair.…”

Effects of Repetitive Reaching Movements on Performance and Postural Control

“…However, for the last few decades, it has been found that the brainstem reticular formation 28) , cerebellum 29,30) , basal ganglia 31) , and cerebral cortex 32) play important roles in the control of dynamic postural balance. Recently, the role of the motor cortex in controlling forearm posture has been investigated.…”

Influence of prolonged wearing of unstable shoes on upright standing postural control

“…Also, the results of the present study indicate that, in both pre-and post-training, wearing unstable shoes leads the postural control system to rely more on reciprocal activation than on co-activation to compensate for the decreased stability compared to barefoot. This has been demonstrated to be more efficient and accurate, but also more challenging for the postural control system (Aruin & Almeida, 1997;Friedli et al, 1984;Garland et al, 1997;Hogan, 1984;Hong et al, 1994;Latash et al, 1995;Massion et al, 1999), and it has been observed also in compensatory postural adjustments in response to an external perturbation (Sousa, et al, 2013a;Sousa, et al, 2014). These findings demonstrate that wearing unstable shoes is more demanding in terms of postural control than barefoot, but lead to a higher efficiency and accuracy in postural commands.…”