Samuel D. Kim

Bio: Samuel D. Kim is an academic researcher from Westmead Hospital. The author has contributed to research in topics: Parkinson's disease & Botulinum toxin. The author has an hindex of 8, co-authored 14 publications receiving 327 citations. Previous affiliations of Samuel D. Kim include University of Sydney.

Postural instability in patients with Parkinson's disease : epidemiology, pathophysiology and management

Abstract: Postural instability is one of the cardinal signs in Parkinson's disease (PD). It can be present even at diagnosis, but becomes more prevalent and worsens with disease progression. It represents one of the most disabling symptoms in the advanced stages of the disease, as it is associated with increased falls and loss of independence. Clinical and posturographic studies have contributed to significant advances in unravelling the complex pathophysiology of postural instability in patients with PD, but it still remains yet to be fully clarified, partly due to the difficulty in distinguishing between the disease process and the compensatory mechanisms, but also due to the fact that non-standardized techniques are used to measure balance and postural instability. There is increasing evidence that physical therapy, especially highly challenging balance exercises, can improve postural stability and reduce the risk of falls, although the long-term effects of physical therapy interventions on postural stability need to be explored given the progressive nature of PD. Pharmacotherapy with dopaminergic medications can provide significant improvements in postural instability in early- to mid-stage PD but the effects tend to wane with time consistent with spread of the disease process to non-dopaminergic pathways in advanced PD. Donepezil has been associated with a reduced risk of falls and methylphenidate has shown potential benefit against freezing of gait, but the results are yet to be replicated in large randomized studies. Surgical treatments, including lesioning and deep brain stimulation surgery targeting the subthalamic nucleus and the globus pallidus internus, tend to only provide modest benefit for postural instability. New surgical targets such as the pedunculopontine nucleus have emerged as a potential specific therapy for postural instability and gait disorder but remain experimental.

An update on Huntington's disease: from the gene to the clinic.

Abstract: Purpose of reviewThis review highlights the recent advances in Huntington's disease, with a particular focus on development of disease biomarkers for use in therapeutic trials in the premotor phase of the disease, as well as the growing literature regarding pathophysiological mechanisms and their re

Treatment of proximal upper limb tremor with botulinum toxin therapy.

Abstract: Background Proximal-dominant upper limb tremor is highly disabling, and there is no effective medical therapy. In this study, we evaluated the efficacy of botulinum toxin (BTX) injections for the treatment of proximal tremor. Methods We conducted a retrospective analysis of open-label treatment with BTX in 19 patients with proximal tremor. The response to therapy was graded into four categories according to self-reported improvements in tremor and function. Results In total, 63% of patients reported moderate or marked benefit, defined as functional improvements sufficient enough to allow feeding or drinking from a cup; whereas 21% of patients reported mild benefit; and 15% of patients reported no benefit. One patient developed severe weakness of shoulder abduction and withdrew from the treatment; otherwise, the therapy was free of side effects. Conclusions The current findings support the efficacy of BTX therapy in the treatment of proximal upper limb tremor with minimal side effects. © International Parkinson and Movement Disorder Society © 2013 International Parkinson and Movement Disorder Society

Dopamine: Functions, Signaling, and Association with Neurological Diseases

Abstract: The dopaminergic system plays important roles in neuromodulation, such as motor control, motivation, reward, cognitive function, maternal, and reproductive behaviors. Dopamine is a neurotransmitter, synthesized in both central nervous system and the periphery, that exerts its actions upon binding to G protein-coupled receptors. Dopamine receptors are widely expressed in the body and function in both the peripheral and the central nervous systems. Dopaminergic signaling pathways are crucial to the maintenance of physiological processes and an unbalanced activity may lead to dysfunctions that are related to neurodegenerative diseases. Unveiling the neurobiology and the molecular mechanisms that underlie these illnesses may contribute to the development of new therapies that could promote a better quality of life for patients worldwide. In this review, we summarize the aspects of dopamine as a catecholaminergic neurotransmitter and discuss dopamine signaling pathways elicited through dopamine receptor activation in normal brain function. Furthermore, we describe the potential involvement of these signaling pathways in evoking the onset and progression of some diseases in the nervous system, such as Parkinson’s, Schizophrenia, Huntington’s, Attention Deficit and Hyperactivity Disorder, and Addiction. A brief description of new dopaminergic drugs recently approved and under development treatments for these ailments is also provided.

Gait impairments in Parkinson's disease.

Abstract: Summary Gait impairments are among the most common and disabling symptoms of Parkinson's disease. Nonetheless, gait is not routinely assessed quantitatively but is described in general terms that are not sensitive to changes ensuing with disease progression. Quantifying multiple gait features (eg, speed, variability, and asymmetry) under natural and more challenging conditions (eg, dual-tasking, turning, and daily living) enhanced sensitivity of gait quantification. Studies of neural connectivity and structural network topology have provided information on the mechanisms of gait impairment. Advances in the understanding of the multifactorial origins of gait changes in patients with Parkinson's disease promoted the development of new intervention strategies, such as neurostimulation and virtual reality, aimed at alleviating gait impairments and enhancing functional mobility. For clinical applicability, it is important to establish clear links between specific gait impairments, their underlying mechanisms, and disease progression to foster the acceptance and usability of quantitative gait measures as outcomes in future disease-modifying clinical trials.

Freezing of gait: a practical approach to management

Abstract: Freezing of gait is a common and disabling symptom in patients with parkinsonism, characterised by sudden and brief episodes of inability to produce effective forward stepping. These episodes typically occur during gait initiation or turning. Treatment is important because freezing of gait is a major risk factor for falls in parkinsonism, and a source of disability to patients. Various treatment approaches exist, including pharmacological and surgical options, as well as physiotherapy and occupational therapy, but evidence is inconclusive for many approaches, and clear treatment protocols are not available. To address this gap, we review medical and non-medical treatment strategies for freezing of gait and present a practical algorithm for the management of this disorder, based on a combination of evidence, when available, and clinical experience of the authors. Further research is needed to formally establish the merits of our proposed treatment protocol.

An update on the diagnosis and treatment of Parkinson disease.

Abstract: Parkinson disease is the second most common neurodegenerative disorder after Alzheimer disease.[1][1] Parkinson disease typically develops between the ages of 55 and 65 years and occurs in 1%–2% of people over the age of 60 years, rising to 3.5% at age 85–89 years.[2][2]–[4][3] About 0.3% of