Postural Control, Gait, and Dopamine Functions in Parkinsonian Movement Disorders

Department of Radiology and Neurology, University of Michigan, 24 Frank Lloyd Wright Drive, Box 362, Ann Arbor, MI 48106, USA.
Clinics in Geriatric Medicine (Impact Factor: 1.83). 12/2006; 22(4):797-812, vi. DOI: 10.1016/j.cger.2006.06.009
Source: PubMed


Postural instability is an important contributor to incapacitation in patients who have parkinsonian disorders. The precise underlying mechanisms of postural instability in these disorders are not fully understood. Several hypothesized integrative functions of the basal ganglia and its dopaminergic system have been proposed; however, those theories have not been fully validated using balance-related experimental data. Because the effectiveness of traditional dopaminergic therapies in reducing falls is limited and often debated in the literature, little agreement exists on how to intervene to address postural deficits. One explanation for the limited effectiveness of dopaminergic pharmacotherapy is loss of postsynaptic dopaminergic receptors with advancing PD and in atypical parkinsonian disorders. Nonmotor cognitive and visual disturbances are now being recognized as new risk factors for falls in PD. Recent evidence also suggests degeneration of the cholinergic pedunculopontine nucleus in PD, which has been associated with akinesia, including gait ignition failure and gait freezing, in this disorder. Degeneration of other neural systems, such as cerebellar ataxia in MSA and the supranuclear gaze palsy in PSP, further contribute to the balance impairments in these atypical parkinsonian disorders.

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    • "However, it is estimated that the annual medical cost associated with PD is between $10,043 and $12,491 (Noyes et al., 2006; Boland and Stacy, 2012) and the long-term use of DA medication is not without side-effects, which may include addiction, behavioral disturbances (Merims and Giladi, 2008), and levodopa-induced dyskinesia (Bezard et al., 2001). More importantly, studies have shown that the underlying mechanisms of postural instability and gait difficulties in PD are dopamine-resistant (Bloem et al., 1996; Bohnen and Cham, 2006), which may explain the greater fall rate in people with PD (Johnson et al., 2013). "
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    ABSTRACT: The use of progressive resistance training (PRT) to improve gait and balance in people with Parkinson’s disease (PD) is an emerging area of interest. However, the main effects of PRT on lower limb function such as gait, balance and leg strength in people with PD remain unclear. Therefore the aim of the meta-analysis is to evaluate the evidence surrounding the use of PRT to improve gait and balance in people with PD. Five electronic databases, from inception to December 2014, were searched to identify the relevant studies. Data extraction was performed by two independent reviewers and methodological quality assessed using the PEDro scale. Standardized mean differences (SMD) and 95% confidence intervals (CIs) of fixed and random effects models were used to calculate the effect sizes between experimental and control groups and I2 33 statistics were used to determine levels of heterogeneity. In total, 7 studies were identified consisting of 172 participants (Experimental n=84; Control n=88). The pooled results showed a moderate but significant effect of PRT on leg strength (SMD 1.42, 95% CI 0.464 to 2.376), however no significant effects were observed for gait speed (SMD 0.418, 95% CI -0.219 to 1.055). No significant effects were observed for balance measures included in this review. In conclusion, our results showed no discernable effect of PRT on gait and balance measures, although this is likely due to the lack of studies available. It may be suggested that PRT be performed in conjunction with balance or task-specific functional training to elicit greater lower limb functional benefits in people with PD.
    Frontiers in aging series 03/2015; DOI:10.3389/fnagi.2015.00040
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    • "Balance impairment or postural instability in individuals with PD is often associated with poor or absent reactive responses following external perturbations, such as performing a rapid step following a slip or trip [23]. However, as degeneration of the basal ganglia affects many physiological systems essential for balance control, balance disorders in PD cannot be addressed to one single function but, rather, are the result of impairments of multiple systems [24-26]. First of all, dysfunction of the basal ganglia influences sensory integration, i.e. the ability of the central nervous system to transform different modalities of sensory information (somatosensory, visual and vestibular) into a single reference frame, which is important for estimation of limb and body position in relation to the environment [27]. "
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    ABSTRACT: Background There is increasing scientific knowledge about the interaction between physiological (musculoskeletal, neuromuscular, cognitive and sensory) systems and their influence on balance and walking impairments in Parkinson’s disease. We have developed a new conceptual framework for balance training, emphasising specific components of balance control related to Parkinson’s disease symptoms by using highly challenging, progressive and varying training conditions. The primary aim of this proposed randomised controlled trial will be to investigate the short-term and long-term effects of a 10-week balance training regime in elderly with Parkinson’s disease. Methods/Design Eighty participants with mild to moderate idiopathic Parkinson’s disease will be recruited and randomly allocated to an intervention group receiving balance training or a control group whose participants will continue to receive their usual care. The intervention will consist of a 10-week group training regime (1-hour training, three times per week), which will be led by two physiotherapists to ensure training progression and safety. The conceptual framework will be applied by addressing specific balance components (sensory integration, anticipatory postural adjustments, motor agility, stability limits) through varying training conditions and structured progression. Assessment will be conducted through a multi-dimensional battery of outcomes, prior to and immediately after the 10-week intervention, and at 9 and 15 months’ follow-up after entering the study. Primary outcome measures will be balance performance (assessed using the Mini Balance Evaluation Systems Test), change in gait velocity (m/s) between single and dual task walking, and fear of falling (evaluated using the Fall Efficacy Scale International). Discussion This study has the potential to provide new insight and knowledge of the effects of specific, varied and challenging balance training on a wide health spectrum in elderly with PD. If found to be effective, this pragmatic approach with translation of theory into practice, can be implemented in existing outpatient care. Trial registration NCT01417598
    BMC Neurology 09/2012; 12(1):111. DOI:10.1186/1471-2377-12-111 · 2.04 Impact Factor
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    • "While having high degrees of internal validity for research purposes, these paradigms lack external and ecologic validity because the floor sliding or rotating underneath a person is not commonly encountered in daily life. Additionally, many of these studies limit their analysis to the components of sway while the base of support remains fixed omitting analysis of protective steps [11] [16] "
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    ABSTRACT: Introduction. Dopamine-replacement medications may improve mobility while not improving responses to postural challenges and could therefore increase fall risk. The purpose of this study was to measure reactive postural responses and gait-related mobility of patients with PD during ON and OFF medication conditions. Methods. Reactive postural responses to the Pull Test and performance of the Functional Gait Assessment (FGA) were recorded from 15 persons with PD during ON and OFF medication conditions. Results. Persons with PD demonstrated no significant difference in the reactive postural responses between medication conditions but demonstrated significantly better performance on the FGA when ON medications compared to OFF. Discussion/Conclusion. Dopamine-replacement medications alone may improve gait-related mobility without improvements in reactive postural responses and therefore could result in iatrogenic increases in fall risk. Rehabilitation providers should be aware of the side effects and limitations of medication treatment and implement interventions to improve postural responses.
    01/2012; 2012(2):692150. DOI:10.1155/2012/692150
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