Motor activation in multiple system atrophy and Parkinson disease: a PET study

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Multiple system atrophy (MSA) is an atypical parkinsonian syndrome characterized by cerebellar impairment and poor levodopa response.
• Understanding motor activation differences in MSA is crucial for diagnosis and treatment.

Purpose of the Study:

• To compare right hand motor activation patterns in MSA patients versus Parkinson's disease (PD) patients and healthy volunteers (HVs).
• To assess the effect of acute levodopa challenge on motor activation in MSA patients.

Main Methods:

• Used H(2)(15)O PET scans to measure regional cerebral blood flow in 18 MSA patients, 8 PD patients, and 10 HVs.
• Analyzed motor activation (vs. rest) in OFF and ON levodopa states using statistical parametric mapping.

Main Results:

• Before levodopa, MSA patients showed less bilateral cerebellar and greater left superior parietal activation than HVs and PD patients.
• PD patients exhibited greater right cerebellar activation than HVs.
• After levodopa, MSA patients had reduced anterior cingulate activation, while PD patients showed increased right cerebellar activation.

Conclusions:

• MSA and PD patients recruit distinct motor networks, suggesting different underlying pathophysiology.
• PD patients may use cerebellar pathways to compensate for basal ganglia dysfunction.
• MSA patients, likely due to cerebellar dysfunction, recruit alternative frontoparietal cortical areas.