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BACKGROUND Deep-brain stimulation is the surgical procedure of choice for patients with advanced Parkinson's disease. The globus pallidus interna and the subthalamic nucleus are accepted targets for this procedure. We compared 24-month outcomes for patients who had undergone bilateral stimulation of the globus pallidus interna (pallidal stimulation) or(More)
Manganese intoxication can result in a syndrome of parkinsonism and dystonia. If these extrapyramidal findings are present, they are likely to be irreversible and even progress after termination of the exposure to manganese. Clinical features are usually sufficient to distinguish these patients from those with Parkinson's disease. The neurological syndrome(More)
Parkinson's disease is a common disorder that leads to motor and cognitive disability. We performed a genome-wide association study of 2,000 individuals with Parkinson's disease (cases) and 1,986 unaffected controls from the NeuroGenetics Research Consortium (NGRC). We confirmed associations with SNCA and MAPT, replicated an association with GAK (using data(More)
We studied the effects of a loading dose of phenytoin on motor cortex excitability in five healthy volunteers. Phenytoin elevated motor thresholds to transcranial magnetic stimulation (TMS) in all subjects, but had no effects on motor-evoked potential amplitudes, silent period durations, and intracortical excitability tested by paired TMS during rest and(More)
We studied the effects of exercise on motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES). Subjects performed 30-second periods of isometric exercise of the extensor carpi radialis until fatigue, which was defined as the inability to maintain half maximum force. The amplitude of MEPs to TMS(More)
Dysfunction of neostriatal medium spiny neurons (MSNs) is hypothesized to underlie late-stage motor complications of Parkinson disease (PD). The authors demonstrate shortened dendrite length of MSNs that was similar in four regions of neostriatum in late-stage PD. In contrast, MSN dendrite spine degeneration was unevenly distributed with the greatest loss(More)
Clinical symptoms of Parkinson's disease (PD) do not manifest until dopamine (DA) neuronal loss reaches a symptomatic threshold. To explore the mechanisms of functional compensation that occur in presynaptic DA nerve terminals in PD, we compared striatal positron emission tomographic (PET) measurements by using [11C]dihydrotetrabenazine ([11C]DTBZ; labeling(More)
BACKGROUND Mutations in the glucocerebrosidase (GBA) gene have been reported to modify risk for Parkinson disease (PD) and dementia with Lewy bodies (DLB). However, these findings have not been consistently replicated, and most studies have had substantial methodological shortcomings. OBJECTIVE To better assess the role of GBA variants in altering risk(More)
Transcranial magnetic stimulation (TMS) causes the corticospinal system to become refractory to subsequent stimuli for up to 200 ms. We examined the phenomenon of paired pulse inhibition with TMS under conditions of rest, ongoing voluntary activation (isometric force generation), and at variable delays following activation (postactivation) of the wrist(More)
We studied the effect of vitamin C, vitamin E, and beta carotene intake on the risk of Parkinson's disease (PD). We did a systematic review and meta-analysis of observational studies published between 1966 and March 2005 searching MEDLINE, EMBASE, and the Cochrane Library. Eight studies were identified (six case-control, one cohort, and one(More)