Drug-Induced Parkinsonism – DaTscan — SCE Neurology MCQ

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ModerateMovement DisordersDrug-Induced Parkinsonism – DaTscanSCE Neurology

A 55-year-old woman is diagnosed with probable drug-induced parkinsonism. She has been on haloperidol for 2 years for a psychiatric condition. Her psychiatrist wishes to differentiate this from idiopathic Parkinson's disease. Which investigation is most helpful?

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Correct answer: D — DaTscan (dopamine transporter SPECT)

DaTscan (ioflupane I-123 SPECT) images presynaptic dopamine transporters in the striatum. In idiopathic PD, there is reduced dopamine transporter uptake (reflecting nigrostriatal neuronal loss). In drug-induced parkinsonism, the dopaminergic neurons are intact but the post-synaptic receptors are blocked — so the DaTscan is NORMAL. A normal DaTscan strongly supports drug-induced parkinsonism over PD. NICE NG71 recommends DaTscan when there is diagnostic uncertainty between PD and other causes of parkinsonism. A: MRI brain is usually normal in both conditions. C: PET-CT is not first-line for this indication. D: Ceruloplasmin is for Wilson disease. E: LP has no role.

Reference: NICE NG71 Parkinson's Disease (2017); EAN DaTscan Guidelines