The clinical syndrome of asymmetric parkinsonism associated with cortical abnormalities along with peculiar pathology has come to be known as corticobasal ganglionic degeneration (CBGD), actually defined simply as corticobasal degeneration (CBD). The definition of the clinical syndrome of CBD is still evolving. Ideally, the complete and accurate characterisation of the clinical syndrome is contingent on diagnosing all subjects who have the disease and excluding subjects who do not. The apparent rarity of the disease makes it a formidable task to accumulate a sufficient number of cases to analyse and obtain meaningful results, as well as making it difficult for physicians to gain familiarity with and to recognise the syndrome. The aim of this work will be to determine the nature of CBD, its clinical impact and its cortical involvement, by evaluating functional imaging and cognitive neuropsychological evaluation.