The role of positron emission tomography imaging in movement disorders

The use of positron emission tomography (PET) imaging may increase the diagnostic accuracy, allow preclinical diagnosis, monitor disease progression, and evaluate the efficacy of therapeutic interventions in Parkinson's disease (PD). PET imaging has demonstrated presynaptic dopaminergic denervation. in patients who have PD or parkinsonism, whereas postsynaptic dopamine receptor studies have generally shown preserved activity in idiopathic PD but decreased activity in patients who have atypical parkinsonism. Huntington's chorea is characterized by more prominent striatal dopamine receptor loss; nigrostriatal denervation is present to a lesser degree. Patients who have Tourette syndrome may have enhanced synaptic dopamine release in the putamen. Functional imaging studies have generally failed, so far, to demonstrate nigrostriatal denervation in essential tremor or idiopathic dystonia.