[¹²³I]-FP-CIT and [^99mTc]-HMPAO single photon emission computed tomography in a new sporadic case of rapid-onset dystonia-parkinsonism

Rapid-onset dystonia-parkinsonism (RDP) is a rare, autosomal-dominantly inherited syndrome characterized by abrupt onset, over hours to days, of dystonic and parkinsonian symptoms. To date, RDP has been described in a small number of families, and in only four sporadic cases. Methods: We here report a new sporadic case of RDP who has a novel de novo mutation in the ATP1A3 gene. Striatal dopamine transporters have been assessed quantitatively using [¹²³I]-FP-CIT SPECT. A volume of interest (VOI) was drawn within the occipital cortex to obtain non-specific activity and specific to non-specific binding ratios (BR) were calculated. A single template of predefined VOI 3D-drawn on right and left caudate nucleus and putamen was applied to the spatially normalized BR images. BR values were compared to those obtained from an age-matched control group and from a group of patients suffering from Parkinson's disease (Hoehn and Yahr score 2 or 3). A [^99mTc]-HMPAO cerebral blood flow study was also performed. Results: In the control group, BR values (mean ± Standard Deviation) were 3.5 ± 0.4 for the left striatum and 3.3 ± 0.3 for the right one. RDP patient's values were 3 and 2.7, respectively. In the Parkinson group, values were 1.6 ± 0.3 and 1.7 ± 0.4, respectively. [^99mTc]-HMPAO scan showed homogeneous cortical and sub-cortical perfusion. Conclusion: Quantification of striatal [¹²³I]-FP-CIT uptake in a new sporadic case of RDP with a novel mutation in the ATP1A3 gene showed values just within the range of normality. [^99mTc]-HMPAO scan was normal.