This study tested the hypothesis that diffusion tensor imaging (DTI) can detect alteration in microscopic integrity of white matter (WM) and basal ganglia (BG) regions known to be involved in Parkinson's disease (PD) pathology. It was also hypothesized that there is an association between the DTI abnormality and PD severity and subtype. DTI at 4 Tesla was obtained in 12 PD and 20 control subjects. The DTI measures of fractional anisotropy (FA) and mean diffusivity (MD) were evaluated using both region of interest (ROI) and voxel-based methods. Movement deficits in PD subjects were assessed using Motor Subscale (Part III) of the Unified Parkinson's Disease Rating Scale (UPDRS). Subtype determination of movement deficits was derived based upon results of subjects’ UPDRS ratings. Reduced FA (p<0.05, corrected) was found in PD subjects in a number of regions, including the precentral gyrus, substantia nigra, putamen, posterior striatum, frontal WM, and in regions related to the supplementary motor areas. Reduced FA in the substantia nigra correlated (p<0.05, corrected) with increased UPDRS motor scores. Significant spatial correlations between FA alterations in putamen and other PD-affected regions were also found in the context of PD subtypes index analysis. Our data suggest that microstructural alterations detected with DTI might serve as a potential biomarker for PD.

This study provides Class III evidence that bilateral subthalamic nucleus deep brain stimulation results in significant improvement in cervical dystonia without bradykinetic side effects.

Orthostatic myoclonus is a unique clinical and physiologic phenomenon that accompanies a slowly progressive and eventually disabling gait disorder in the elderly. This phenomenon often arises in the company of more widespread CNS disease.

Background: Respiratory stridor, sleep-disordered breathing, and respiratory insufficiency are part of the clinical spectrum of multiple-system atrophy (MSA). We have encountered cases where these were presenting symptoms, with the diagnosis of MSA being initially unrecognized. Objective: To describe cases in which breathing difficulties were the initial and primary manifestation of MSA.

a b s t r a c tIntroduction: Depletion of neuronal glutathione may contribute to the pathogenesis of Parkinson's disease (PD). N-acetylcysteine (NAC) can restore neuronal glutathione levels, but it has not been established whether NAC can cross the bloodebrain barrier in humans. Methods: Twelve patients with PD were given oral NAC twice daily for 2 days. Three doses were compared: 7 mg/kg, 35 mg/kg, and 70 mg/kg. NAC, cysteine, and glutathione were measured in the cerebrospinal fluid (CSF) at baseline and 90 min after the last dose. Cognitive and motor functions were assessed pre-and post-NAC administration using the Montreal Cognitive Assessment (MoCA) and the Unified Parkinson's Disease Rating Scale part III motor subscore (UPDRS-III). Results: Oral NAC produced a dose-dependent increase in CSF NAC concentrations (p < 0.001), with the highest dose producing a CSF concentration of 9.26 ± 1.62 mM. There were no significant adverse events.NAC had no acute effect on motor or cognitive function. Conclusion: Orally administered NAC produces biologically relevant CSF NAC concentrations at doses that are well tolerated. The findings support the feasibility of NAC as a potential disease-modifying therapy for PD.

Background The pedunculopontine nucleus (PPN) is a brainstem structure with widespread connections to the basal ganglia. Despite the recent introduction of PPN deep brain stimulation (DBS) for the treatment of gait disorders, little is known about its physiology in humans. Methods We analyzed the discharge characteristics of single neurons in the PPN region in four patients and PPN local field potentials (LFP) in one patient, recorded during the course of DBS implantation. Two patients had Parkinson’s disease and two had non-sinemet responsive parkinsonism. Cell locations were plotted in the coordinate system of a human brainstem atlas. Results Fifty-six units in the PPN region were studied, of which 32 mapped to within PPN boundaries. The mean (+/− SD) discharge rate of neurons in the PPN was 23.2 (+/− 15.6) Hz. Spontaneous neuronal firing rate and burst discharge rate were significantly different between neurons in the region dorsal to PPN and those in the PPN. Responses to passive movement of contralateral and ipsilateral limbs were found. Theta and beta band oscillations were present in the PPN LFP. Conclusion PPN discharge characteristics may prove useful in the electrophysiologic identification of PPN during DBS implantation surgery.

The risk of developing levodopa-associated dyskinesia is known to vary inversely with the age of Parkinson's disease onset. This study quantifies dyskinesia risks for different Parkinson's onset ages in a patient population treated at the Parkinson's Disease Research, Education, and Clinical Center at the San Francisco Veterans Affairs Medical Center. Medical records were reviewed to determine age of Parkinson's onset, medication history, and dyskinesia onset. Dyskinesia risks were determined by using Kaplan-Meier analysis. Cox proportional hazard models were used to compare age groups and to perform multivariate modeling. This study included 109 patients with Parkinson's, 105 of whom had onset of symptoms after 1989. At 5 years of levodopa treatment, the dyskinesia risk for patients with onset age 40-49 was 70%, decreasing to 42% for onset ages 50-59, 33% for onset ages 60-69, and 24% for onset ages 70-79. Pairwise comparisons between the 40-49 age group and the other age groups were statistically significant in time-to-event models. After 5 years of levodopa treatment, dyskinesia risks became uniformly high regardless of age of onset. These results suggest it is appropriate to use different baseline dyskinesia risks in clinical decision-making for patients on the basis of their ages of onset. However, the most significant difference occurs between ages 40-49 and ages 50-79, and if more than 5 years of levodopa therapy are anticipated, dyskinesia risk may have less utility when deciding upon Parkinson's therapy. Drug studies for Parkinson's disease should also take age of Parkinson's onset into account when analyzing dyskinesia outcomes.

N-acetyl cysteine (NAC) supports the synthesis of glutathione (GSH), an essential substrate for fast, enzymatically catalyzed oxidant scavenging and protein repair processes. NAC is entering clinical trials for adrenoleukodystrophy, Parkinson's disease, schizophrenia, and other disorders in which oxidative stress may contribute to disease progression. However, these trials are hampered by uncertainty about the dose of NAC required to achieve biological effects in human brain. Here we describe an approach to this issue in which mice are used to establish the levels of NAC in cerebrospinal fluid (CSF) required to affect brain neurons. NAC dosing in humans can then be calibrated to achieve these NAC levels in human CSF. The mice were treated with NAC over a range of doses, followed by assessments of neuronal GSH levels and neuronal antioxidant capacity in ex vivo brain slices. Neuronal GSH levels and antioxidant capacity were augmented at NAC doses that produced peak CSF NAC concentrations of ≥50 nM. Oral NAC administration to humans produced CSF concentrations of up to 10 μM, thus demonstrating that oral NAC administration can surpass the levels required for biological activity in brain. Variations of this approach may similarly facilitate and rationalize drug dosing for other agents targeting central nervous system disorders.