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Can the early presence of autonomic dysfunction aid diagnosis in parkinsonism?
  1. CHRISTOPHER J MATHIAS
  1. Neurovascular Medicine Unit, Division of Neuroscience and Psychological Medicine, Imperial College School of Medicine at St Mary’s Hospital, Praed Street, London W2 1NY, UK and Autonomic Unit, National Hospital for Neurology and Neurosurgery, Queen Square and University Department of Clinical Neurology, Institute of Neurology, University College London, London WC1, UK.

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    Clinical, laboratory, and in particular neuropathological studies, indicate that parkinsonism is the presenting feature of a range of disorders. Although most are likely to have classic Parkinson’s disease (PD), a substantial number have disorders that include multiple system atrophy (MSA; about 10–15%), progressive supranuclear palsy (PSP), and relatively rare disorders such as dementia with Lewy bodies (DLB) and corticobasal degeneration (CBD). The natural history of these disorders varies widely. Laboratory tests have been used to help differentiate these disorders, but some are not readily accessible, most have been based on patients with established disease, and their sensitivity and specificity, especially in the early stages, are unknown. Clinical pointers therefore, can be particularly valuable, as a probable diagnosis is important for discussions on prognosis, for devising investigational and therapeutic strategies, for anticipation of complications, and for forward planning of multidisciplinary support services that often are the mainstay of management. In the paper by Wenning et al (this volume pp 620−3),1 the frequency and latency of two symptoms of autonomic dysfunction (orthostatic hypotension and urinary incontinence), were determined in neuropathologically established parkinsonism. Symptomatic orthostatic hypotension was present in the majority with MSA (87%) and PD (78%), and in 45% of PSP; it was minimal in DLB (15%) and not found in CBD (0%). Urinary incontinence was present in a similar proportion of MSA (87%), PD (82%) and PSP (75%), and also in DLB (64%) and CBD (62%). In MSA, orthostatic hypotension occurred more often within a year, unlike PD. The diagnostic sensitivity and positive predictive value was higher for orthostatic hypotension than for urinary incontinence, especially in MSA.

    A particular strength of the study was the large number with non-PD syndromes, although the number with PD was relatively small. There also were weaknesses, as may be expected in a retrospective study from multiple centres, especially as relevant cardiovascular autonomic and uroneurological testing2 3 was not performed. In a previous study in PD,4 the prevalence of symptomatic orthostatic hypotension was 20%, although asymptomatic orthostatic hypotension occurred in a further 38%; these figures are considerably lower than those reported by Wenning et al. Both orthostatic hypotension and urinary incontinence may result from various autonomic and non-autonomic factors that are unrelated to the neuropathological processes in parkinsonism3 5; examples include orthostatic hypotension due to drug treatment and urinary incontinence caused by pelvic floor weakness in multiparous women.

    In recent years the range of symptoms resulting from orthostatic hypotension has been defined further, along with factors in daily life that influence both symptoms and orthostatic blood pressure fall5; this applies also to urinary symptoms. These symptoms should be enquired after in the clinic; furthermore, orthostatic hypotension can be readily checked. Ideally, the presence of postural hypotensive and urological symptoms (especially if accompanied in the male by erectile dysfunction), warrants appropriate laboratory evaluation. Although these may not always conclusively point to the precise diagnosis, they determine the functional deficit and contribute positively to management, as autonomic dysfunction can result in substantial morbidity.

    This paper therefore, emphasises the value of detailed and relevant clinical evaluation in parkinsonism. It reinforces the view that autonomic dysfunction needs to be actively enquired after and investigated, as it may provide clues to diagnosis, and additionally aid management.

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