Vascular parkinsonism: a review of the precision and frequency of the diagnosis.

Over the past century vascular parkinsonism (VP) has been established, dismissed and recently re-established as a possible clinical entity. We review the clinical features that have been proposed to suggest the diagnosis and explore how precisely VP has been defined on the basis of clinical, as well as radiological and pathological grounds. Estimates of the frequency of this condition have been based on population-based incidence and prevalence studies and also using case series of all types or parkinsonism. We performed a systematic search for all of these published studies and present their estimates of frequency. We conclude that the wide variations in these estimates may be largely explicable by variation in case definition. When studies are limited to those with either imaging or pathological support for the diagnosis, all but one estimate that 3-6% of all cases of parkinsonism have a vascular cause. In addition, features of parkinsonism have been seen in up to 38% of lacunar stroke patients at 1 year. On the basis of this appreciably high frequency, and with consideration of the implications for clinician and scientist, we suggest that VP needs to be recognised as an important clinical diagnosis, and includes a spectrum of distinct pathophysiological entities.