Dopaminergic function in patients with posttraumatic parkinsonism: an 18F-dopa PET study

Area of Science:

• Neurology
• Neuroimaging
• Nuclear Medicine

Background:

• Posttraumatic encephalopathy (PTE) encompasses diverse neurological deficits.
• A rare "striatal" variant presents with posttraumatic parkinsonism (PTP), often challenging to differentiate from idiopathic Parkinson's disease (PD).

Purpose of the Study:

• To investigate the utility of 18F-dopa Positron Emission Tomography (PET) in differentiating PTP from idiopathic PD.
• To characterize the in vivo neurochemical profile of PTP using 18F-dopa PET.

Main Methods:

• Six patients with presumed PTP underwent 18F-dopa PET scans.
• PET findings were compared with age-matched healthy controls and idiopathic PD patients.
• Quantitative analysis of 18F-dopa uptake in the caudate and putamen was performed.

Main Results:

• PTP patients exhibited a uniform 40% reduction in 18F-dopa uptake in the caudate and putamen compared to controls.
• Putamen uptake in PTP was significantly higher than in PD patients, while caudate uptake was lower.
• The caudate:putamen uptake ratio in PTP was similar to controls but significantly lower than in PD patients.

Conclusions:

• 18F-dopa PET can help distinguish PTP from idiopathic PD by revealing uniform nigrostriatal involvement in PTP.
• The findings suggest relative sparing of caudate function in PTP compared to PD.
• Delayed neurological deficits following cumulative head trauma are supported by these findings.