ABSTRACT
Parkinsonism is a clinical syndrome with three cardinal features: akinesia, rigidity and tremor. Akinesia is a requisite sign for diagnosis and is usually accompanied by rigidity: tremor is a variable finding. The causes of parkinsonism can be classified into three major groups: idiopathic Parkinson's Disease (IPD), atypical parkinsonian syndromes and other neurodegenerative disorders, and secondary or symptomatic causes. This chapter discusses the diagnosis of IPD and briefly reviews the conditions that most commonly mimic IPD with particular emphasis on the atypical or 'parkinsonism plus' syndromes. The diagnosis of IPD remains entirely clinical at present since there are no specific biological markers. Some investigations are useful in recognising other causes of parkinsonism. Akinesia is the core feature of parkinsonism and must be present if the diagnosis is to be sustained. Rigidity is recognised as an increase in resistance to passive movements around a joint. Pathological changes and cell loss develop gradually in IPD during an unknown period of time.
