Elsevier

The Lancet

Volume 354, Issue 9192, 20 November 1999, Pages 1771-1775
The Lancet

Articles
Prevalence of progressive supranuclear palsy and multiple system atrophy: a cross-sectional study

https://doi.org/10.1016/S0140-6736(99)04137-9Get rights and content

Summary

Background

The prevalence of progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) in the general population is unknown. Clinicopathological studies of patients diagnosed as having Parkinson's disease suggest that the two disorders may be underdiagnosed. We investigated the population prevalence of these disorders.

Methods

We screened computerised records of 15 general practices in London, UK, for patients with specific diagnostic labels suggestive of Parkinson's disease or parkinsonism and all patients who had ever received antiparkinsonian medication. We assessed eligible patients by review of records, interview, physical examination, and video recordings of neurological signs for independent diagnostic confirmation. We diagnosed parkinsonian disorders according to published criteria and further reviewed patients with atypical features after 1 year.

Findings

The participation rate was 84%. The age-adjusted prevalence for PSP was 6·4 per 100000 (five probable and one possible case [95% Cl 2·3–10·6]) and for MSA 4·4 per 100000 (two probable and two possible cases [1·2–7·6]). An additional four atypical patients were identified at 1 year but did not fulfil criteria for PSP or MSA.

Interpretation

Our results suggest that the true prevalence of PSP and MSA has been underestimated, since many patients in the community remain undiagnosed or misdiagnosed.

Introduction

Progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) are two distinct and well described neurodegenerative disorders, but little is known about their prevalence in the general population. They are frequently misdiagnosed, especially as Parkinson's disease. Diagnosis of PSP and MSA may be especially difficult in the early stages of these diseases before atypical features have clearly emerged. Patients should ideally, therefore, be regularly reassessed by movement-disorder specialists.1 In the UK Parkinson's Disease Society Brain Bank, neuropathological assessment of 100 patients who died with a diagnosis of Parkinson's disease showed that around 6% actually had PSP and 5% MSA.2 Among 35 patients who had pathologically proven MSA, 55% of the 22 patients from institutions other than our own died with erroneous diagnoses of Parkinson's disease.3 From 1989 to 1994, 7·9% and 9·9% of 303 brains donated to the brain bank showed PSP and MSA, respectively (S Daniel, personal communication). However, patients with PSP and MSA are probably over-represented in studies of Parkinson's disease brain banks,4 and, therefore, estimates of prevalence made through extrapolation from these results may be misleading. Moreover, because survival in PSP and MSA is much shorter than that in Parkinson's disease, such data are better indicators of incidence than prevalence.

Prevalence studies of Parkinson's disease generally exclude atypical parkinsonian patients or include them under the diagnosis of parkinsonism.5, 6 We undertook a population-based study on the prevalence of parkinsonism and its different subtypes to estimate the prevalence of PSP and MSA.

Section snippets

Patients and methods

We obtained ethics approval from the National Hospital for Neurology and Neurosurgery and the Institute of Neurology Joint Medical Ethics Committee.

Results

The total screened population was 121 608 people, of whom 23 859 were older than 55 years, and 14 272 older than 65 years. 679 patients were selected by screening, but 438 patients were excluded after review of records. Therefore, we studied 241 eligible patients. Patients were excluded because of: use of antiparkinsonian drugs for other indications (334 [76%] patients, 286 of whom had been receiving an anticholinergic in association with a dopamine antagonist for a psychiatric disorder); a

Discussion

With use of strict clinical diagnostic criteria, we assessed the population prevalence of PSP and MSA. Our results illustrate the importance of community-based studies, since none of the patients with PSP and only one with MSA were previously diagnosed. Initially, we used wide inclusion criteria so that as many patients as possible with potential parkinsonism could be identified. All patients were assessed by a neurologist with specialist experience in movement disorders, and almost all had a

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