Positron emission tomographic studies of the subcortical degenerations and dystonia.

Reported PET findings in subcortical and corticobasal degenerations, and in dystonia, are summarized in Table 3. It can be seen that, although PET is not a diagnostic technique, clinical examination combined with PET findings can help to distinguish between the various akinetic-rigid syndromes, with the proviso that pathologic validation of many PET studies is still awaited. More importantly, PET is now providing information about the functional effects of these various subcortical degenerations, and about dystonia. It is likely that more information will become available about the nature of the functional corrections between cortex, thalamus, and basal ganglia as increasingly sophisticated activation paradigms are designed for PET studies on movement disorders.