SPECT Molecular Imaging in Atypical Parkinsonism.

Atypical parkinsonism is the second most common diagnosis for patients with hypokinetic movement disorders. Beside common parkinsonian symptoms (i.e. bradykinesia and muscular rigidity) patients may also present a variety of additional motor and non-motor symptoms, such as oculomotor abnormalities, postural instability, ataxia, limb apraxia, autonomic dysfunctions, etc. Clinical heterogeneity and gradual manifestation during the disease course often hamper the diagnosis and adequate treatment. This chapter provides an overview of the contribution of single photon emission computed tomography (SPECT) in the differential diagnosis of atypical parkinsonism.