Parkinson's disease: clinical features.

Idiopathic Parkinson's disease (IPD) is a common and universal condition. Although its cause is still unknown, we now have some insights into pathogenetic mechanisms and genetic factors that may be important in causing the selective neuronal loss and presence of Lewy bodies that characterize its pathology. Clinically, as well as the classic features of akinesia, rigidity and often rest tremor, patients may present a wide range of other symptoms including pain, other sensory symptoms, impaired olfaction, personality change, mild executive cognitive deficits, dementia and depression, an extraordinary richness of symptoms and signs rendered even more extraordinary by the long-term effects of drug treatment. While there may be little difficulty recognizing typical cases of IPD, there has been, at least until recently, a considerable misdiagnosis rate in both atremulous (confusion with ageing, vascular disease, multiple system atrophy (MSA) or progressive supranuclear palsy (PSP)) and tremulous (confusion with essential tremor (ET), dystonic tremor, and MSA) forms. However, increasing awareness of the clinical features of all these conditions, together with adherence to exacting diagnostic criteria, is leading to improved diagnosis, which is crucial for patients (who want to know what the future holds for them), for their treatment (giving them the right drug and not the wrong one) and for research (since all the different diseases above have different aetiologies and pathology).