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OBJECTIVE Motor asymmetry in Parkinson's disease (PD) is evident clinically and on functional neuroimaging, but not reported in diffusion tensor imaging (DTI). We aim to determine if asymmetry in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) can be detected in the substantia nigra (SN) of PD subjects. METHODS DTI scans were performed(More)
OBJECTIVE To investigate in vivo the impact of age on nigrostriatal dopamine dysfunction in Parkinson's disease (PD). METHODS PD patients (n = 78) and healthy control subjects (n = 35) underwent longitudinal positron emission tomography assessments using 3 presynaptic dopamine markers: (1) [¹¹C](±)dihydrotetrabenazine (DTBZ), to estimate the density of(More)
BACKGROUND AND OBJECTIVES The neuroanatomical substrates underlying cognitive impairment in Parkinson's disease (PD) remain poorly understood. To address this gap, we compared the grey matter atrophy patterns in PD patients with mild cognitive impairment (PD-MCI) with PD patients having no cognitive impairment (PD-NCI), and examined relationships between(More)
OBJECTIVE To study the interaction between levodopa and the feedback process on set-shifting in Parkinson's disease (PD). METHODS Functional magnetic resonance imaging (fMRI) studies were performed on 13 PD subjects and 17 age-matched healthy controls while they performed a modified card-sorting task. Experimental time periods were defined based on the(More)
BACKGROUND Adult-onset type II citrullinemia is an inborn error of urea cycle metabolism that can lead to hyperammonemic encephalopathy and coma. However, type II citrullinemia is rare outside Japan, and diagnosis and treatment can be delayed. Magnetic resonance spectroscopy may be a useful adjunct to magnetic resonance imaging, and has been applied to(More)
BACKGROUND Early diagnosis of cognitive impairment in PD would allow appropriate monitoring and timely intervention to reduce the progression to dementia (PDD). OBJECTIVE To study the usefulness of the Montreal Cognitive Assessment (MoCA) in the screening for mild cognitive impairment (PD-MCI) and its predictive utility in determining longitudinal(More)
Data on the prevalence and severity of cognitive impairment among patients with newly diagnosed idiopathic Parkinson's disease (PD) is limited. Using a prospectively collected clinical database, we studied the longitudinal trend of mini-mental state examination (MMSE) change and baseline factors predictive for MMSE decline. One hundred six patients with(More)
BACKGROUND Mild cognitive impairment (MCI) and dementia contribute to a poor quality of life among patients with PD. The influence of cerebral ischemia as a risk factor for MCI in PD has not been adequately investigated. To address this issue, we examined the influence of the volume and distribution of white matter hyperintensity (WMH) as a risk factor for(More)
BACKGROUND Longitudinal neuroimaging studies could provide insights into pathophysiology of cognitive impairment in PD. We examined the role of hippocampal atrophy and cerebral white matter disease as risk factors for mild cognitive impairment and dementia in PD. METHODS Prospective longitudinal study of patients with mild PD in a tertiary neurology(More)
In this paper, we propose a novel anti-phase tremor compensation method using surface electromyography (SEMG) and accelerometer (ACC). The usefulness of the SEMG signal is that it precedes the generated joint movement by 20–100 ms (electromechanical delay, EMD). Hence by detecting the tremor in advance, there is enough time window to do the necessary(More)