Imaging in Movement Disorders.

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Movement disorders, particularly parkinsonism, pose diagnostic challenges.
• Accurate diagnosis and understanding of pathophysiology are crucial for effective management.
• Current diagnostic tools for Parkinson disease (PD) rely heavily on clinical assessment due to a lack of direct biomarkers.

Approach:

• Review of commonly used and emerging neuroimaging modalities for movement disorders.
• Evaluation of diagnostic utility, differential diagnosis capabilities, and pathophysiological insights provided by various imaging techniques.
• Exploration of the limitations and future potential of neuroimaging in parkinsonism.

Key Points:

• Iron-sensitive and neuromelanin-sensitive MRI can directly assess nigral dopaminergic neuron integrity in Parkinson disease (PD).
• Current PET/SPECT tracers for presynaptic function correlate with nigral pathology only in early PD.
• Cholinergic PET targeting the vesicular acetylcholine transporter offers new insights into PD symptoms like dementia and falls.

Conclusions:

• Parkinson disease (PD) remains a clinical diagnosis due to the absence of direct biomarkers for misfolded alpha-synuclein.
• Limitations exist in the specificity and ability of current PET/SPECT striatal measures to reflect nigral pathology in moderate to severe PD.
• Multimodal imaging approaches hold significant potential for advancing the understanding and diagnosis of nigral pathology and its functional consequences in movement disorders.