[The problem of accurate diagnosis of Parkinson disease]

A definite diagnosis of Parkinson's disease cannot be made solely on clinical grounds. None of the cardinal signs (tremor, rigidity, or bradykinesia) is entirely specific, including asymmetric presentation. A favourable response to levodopa may be found in different degenerative parkinsonisms or there may be drug-induced dyskinesias and fluctuations. "Probable" or "possible" as diagnostic categories depend on the presence or one or more cardinal signs, absence of potential etiologic factors (exposure to antidopaminergic drugs, among others), and atypical clinical manifestations early in disease course as dementia, falls and instability, erectile and micturition disturbances and unilateral neglect. Preclinical detection (positron emission tomography and molecular genetics in some familial forms) is a desirable goal with a view to neuroprotection. We emphasise some prodromal and early complaints as well as clinical skills to detect cardinal signs during early.