Neuroimaging Detectable Differences between Parkinson's Disease Motor Subtypes: A Systematic Review

Area of Science:

• Neuroimaging and Neurology
• Neuroscience Research
• Medical Imaging Applications

Background:

• Parkinson's disease (PD) subtypes, including tremor-dominant (TD) and non-tremor-dominant (nTD), lack fully differentiated neuroanatomical substrates.
• Understanding symptom-specific pathoanatomical markers is crucial for earlier diagnosis and personalized treatment of PD.
• This review synthesizes neuroimaging literature comparing PD motor subtypes.

Purpose of the Study:

• To provide an overview of neuroimaging studies comparing Parkinson's disease motor subtypes.
• To elucidate the neuroanatomical differences between TD-PD and nTD-PD.
• To identify key neuroimaging findings related to PD motor subtypes.

Main Methods:

• A systematic literature review adhering to PRISMA guidelines was performed.
• PubMed database was searched using terms: "Parkinson's disease", "MRI", and "motor subtypes" (TD, nTD, PIGD, AR).
• Findings were analyzed from macro to micro levels (structural, functional, molecular) and by imaging methodology.

Main Results:

• Neuroimaging methods like diffusion imaging and PET show potential in distinguishing PD motor subtypes, though findings are sometimes mixed.
• Non-tremor-dominant PD patients exhibit more severe neuroalterations compared to tremor-dominant PD patients.
• nTD-PD is associated with striato-thalamo-cortical (STC) circuitry deficits, while TD-PD is linked to cerebello-thalamo-cortical (CTC) circuitry dysfunction.

Conclusions:

• Deficits in STC and CTC circuitry appear to be central to Parkinson's disease and its subtypes.
• Future research should emphasize multimodal neuroimaging.
• Higher sensitivity techniques are needed to better delineate subcortical structures in motor diseases like PD.