Correspondence Address:
Shakya Bhattacharjee
Flat 96, 21, Plymbridge Lane, Plymouth, PL68AX
UK

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Sir,

A 54-year-old man on valproate because of bipolar affective disorders developed extra-pyramidal symptoms suggestive of drug-induced parkinsonism. His symptoms persisted despite stopping valproate. He had a dopamine transporter (DaT) scan and single-photon emission computed tomography (SPECT) scan. The DaT scan showed abnormality (Grade 1) [Table 1] in the right putaminal tracer uptake suggestive of degenerative parkinsonism instead of drug-induced parkinsonism [Figure 1]a and [Figure 1]b.[1],[2]{Figure 1}{Table 1}

DaT is the presynaptic transmembrane protein of the dopaminergic synapses. It transports dopamine back to the presynaptic neurons from the synaptic cleft.123 I-ioflupane is a molecular imaging agent used in DaT imaging to demonstrate the location and concentration of DaTs in the synapses. Tc99m-TRODAT and F-18 FDOPA positron emission tomography scan can also assess the DaT activity and the integrity of the presynaptic nigrostriatal function.[3]

DaT SPECT brain scan is helpful to distinguish between pre- (degenerative) and post-synaptic (such as drug-induced or vascular parkinsonism) parkinsonism.[4] DaT imaging is usually normal in postsynaptic parkinsonism, but abnormal in the presynaptic variety.[1] The degenerative presynaptic parkinsonism includes sub-types such as idiopathic Parkinson's disease, progressive supranuclear palsy, multiple system atrophy, Lewy body dementia, and corticobasal degeneration. Though this SPECT scan can distinguish between pre- and post-synaptic parkinsonism, it cannot distinguish among the sub-types of degenerative parkinsonism mentioned above.[1],[4]

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