Natural history of multiple system atrophy in the USA: a prospective cohort study.

BACKGROUND: Multiple system atrophy is a rare, fatal neurodegenerative disorder with symptoms of autonomic failure plus parkinsonism, cerebellar ataxia, or both. We report results of the first prospective natural history study of multiple system atrophy in the USA, and the effects of phenotype and autonomic failure on prognosis. METHODS: We recruited participants with probable multiple system atrophy-of either the parkinsonism subtype (MSA-P) or the cerebellar ataxia subtype (MSA-C)-at 12 neurology centres in the USA specialising in movement or autonomic disorders. We followed up patients every 6 months for 5 years and assessed them with the Unified Multiple System Atrophy Rating Scale part I (UMSARS I; a functional score of symptoms and ability to undertake activities of daily living), UMSARS II (neurological motor evaluation), and the Composite Autonomic Symptoms Scale (COMPASS)-select (a measure of autonomic symptoms and autonomic functional status). We assessed potential predictors of outcome. We used Cox proportional hazards models to calculate univariate hazard ratios for shorter survival using age at disease onset as a continuous variable and sex, clinical phenotype, and early development of neurological and autonomic manifestations as categorical variables. FINDINGS: We recruited 175 participants. Mean age at study entry was 63·4 years (SD 8·6). Median survival from symptom onset was 9·8 years (95% CI 8·8-10·7) and median survival from enrolment was 1·8 years (0·9-2·7). Participants with severe symptomatic autonomic failure (symptomatic orthostatic hypotension, urinary incontinence, or both) at diagnosis (n=62) had a worse prognosis than those without severe disease (n=113; median survival 8·0 years, 95% CI 6·5-9·5 vs 10·3 years, 9·3-11·4; p=0·021). At baseline, patients with MSA-P (n=126) and MSA-C (n=49) had much the same symptoms and functional status: mean UMSARS I 25·2 (SD 8·08) versus 24·6 (8·34; p=0·835); mean UMSARS II 26·4 (8·8) versus 25·4 (10·5; p=0·764); COMPASS-select 43·5 (18·7) versus 42·8 (19·6; p=0·835). Progression over 5 years, assessed by change in UMSARS I, UMSARS II, and COMPASS-select, was modest. INTERPRETATION: Probable multiple system atrophy is a late-stage disease with short survival. The natural histories of MSA-P and MSA-C are similar and severe symptomatic autonomic failure at diagnosis is associated with worse prognosis. FUNDING: US National Institutes of Health, Mayo Clinic, and Kathy Shih Memorial Foundation.

Potential outcome measures and trial design issues for multiple system atrophy.

Multiple system atrophy (MSA) is a neurodegenerative disorder exhibiting a combination of parkinsonism, cerebellar ataxia, and autonomic failure. A disease-specific scale, the Unified Multiple System Atrophy Rating Scale (UMSARS), has been developed and validated to measure progression of MSA, but its use as an outcome measure for therapeutic trials has not been evaluated. On the basis of twelve months of follow-up from an observational study of 67 patients with probable MSA, we evaluated three disease-specific scores: Activities of Daily Living, Motor Examination, and a combined score from the UMSARS and two general health scores, the Physical Health and Mental Health scores of the SF-36 health survey, for their use as outcome measures in a therapeutic trial. We discuss related design issues and provide sample size estimates. Scores based on the disease-specific UMSARS seemed to be equal or superior to scores based on the SF-36 health survey. They appeared to capture disease progression, were well correlated and required the smallest sample size. The UMSARS Motor Examination score exhibited the most favorable characteristics as an outcome measure for a therapeutic trial in MSA with 1 year of follow-up.

Pramipexole vs levodopa as initial treatment for Parkinson disease: a 4-year randomized controlled trial.

BACKGROUND: The best way to initiate dopaminergic therapy for early Parkinson disease remains unclear. OBJECTIVE: To compare initial treatment with pramipexole vs levodopa in early Parkinson disease, followed by levodopa supplementation, with respect to the development of dopaminergic motor complications, other adverse events, and functional and quality-of-life outcomes. DESIGN: Multicenter, parallel-group, double-blind, randomized controlled trial. SETTING: Academic movement disorders clinics at 22 sites in the United States and Canada. PATIENTS: Patients with early Parkinson disease (N = 301) who required dopaminergic therapy to treat emerging disability, enrolled between October 1996 and August 1997 and observed until August 2001. INTERVENTION: Subjects were randomly assigned to receive 0.5 mg of pramipexole 3 times per day with levodopa placebo (n = 151) or 25/100 mg of carbidopa/levodopa 3 times per day with pramipexole placebo (n = 150). Dosage was escalated during the first 10 weeks for patients with ongoing disability. Thereafter, investigators were permitted to add open-label levodopa or other antiparkinsonian medications to treat ongoing or emerging disability. MAIN OUTCOME MEASURES: Time to the first occurrence of dopaminergic complications: wearing off, dyskinesias, on-off fluctuations, and freezing; changes in the Unified Parkinson's Disease Rating Scale and quality-of-life scales; and adverse events. RESULTS: Initial pramipexole treatment resulted in a significant reduction in the risk of developing dyskinesias (24.5% vs 54%; hazard ratio, 0.37; 95% confidence interval [CI], 0.25-0.56; P<.001) and wearing off (47% vs 62.7%; hazard ratio, 0.68; 95% CI, 0.49-0.63; P =.02). Initial levodopa treatment resulted in a significant reduction in the risk of freezing (25.3% vs 37.1%; hazard ratio, 1.7; 95% CI, 1.11-2.59; P =.01). By 48 months, the occurrence of disabling dyskinesias was uncommon and did not significantly differ between the 2 groups. The mean improvement in the total Unified Parkinson's Disease Rating Scale score from baseline to 48 months was greater in the levodopa group than in the pramipexole group (2 +/- 15.4 points vs -3.2 +/- 17.3 points, P =.003). Somnolence (36% vs 21%, P =.005) and edema (42% vs 15%, P<.001) were more common in pramipexole-treated subjects than in levodopa-treated subjects. Mean changes in quality-of-life scores did not differ between the groups. CONCLUSIONS: Initial treatment with pramipexole resulted in lower incidences of dyskinesias and wearing off compared with initial treatment with levodopa. Initial treatment with levodopa resulted in lower incidences of freezing, somnolence, and edema and provided for better symptomatic control, as measured by the Unified Parkinson's Disease Rating Scale, compared with initial treatment with pramipexole. Both options resulted in similar quality of life. Levodopa and pramipexole both appear to be reasonable options as initial dopaminergic therapy for Parkinson disease, but they are associated with different efficacy and adverse-effect profiles.

Structure, odd lines and topological entropy of disorder of amorphous silicon.

A continuous random network model of amorphous silicon, subject to periodic boundary conditions, is partitioned into cells bounded by irreducible rings. An algorithm has been developed to find the cells and the rings that bound them. A thread can be imagined to pass through odd rings (rings containing an odd number of atoms) without passing through even rings. Such a thread is an algorithmic realization of an odd line, which is the only topological defect in glass or amorphous condensed matter. The topological entropy of disorder associated with these odd lines is found to be approximately 80% of the value for an ideal tetrahedrally bonded random network of atoms for which the rings that bound the cells are statistically independent.