Atypical parkinsonian disorders

A number of atypical parkinsonian disorders has emerged in movement disorders clinics over the last two decades including multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and dementia with Lewy bodies (DLB). These disorders are characterized by distinctive sets of atypical features that have been partly acknowledged by recent consensus diagnostic criteria. Early severe autonomic and urological failure is the clinical hallmark of MSA whereas early falls and supranuclear downgaze palsy discriminate PSR CBD is distinguished from other atypical parkinsonian disorders by prominent cortical features including apraxia and cortical sensory loss, and the dementia of DLB is characterized by visual hallucinations and fluctuating cognition. The role of additional investigations in the diagnosis of atypical parkinsonism has been further delineated during the last decade, however, consensus regarding laboratory supported diagnostic criteria remains to be established. Early diagnosis of atypical parkinsonian disorders is important not only because of prognostic implications, but also because of variable therapeutic targets such as autonomic failure, apraxia or dementia.