Reduced 123I Ioflupane Binding in Bilateral Diabetic Chorea: Findings With 18F FDG PET, 99mTc ECD SPECT, and 123I MIBG Scintigraphy.

We report a 64-year-old man with diabetic chorea whom we investigated with dopamine transporter SPECT, F FDG PET, Tc ethylcysteinate dimer (ECD) SPECT, and I metaiodobenzylguanidine (MIBG) scintigraphy. Dopamine transporter SPECT revealed reduced I ioflupane binding in the bilateral striatum. F FDG PET showed metabolic dysfunction in the bilateral striatum, as shown in earlier studies. Tc ECD SPECT revealed reduced brain perfusion in the bilateral caudate nucleus and putamen. I MIBG scintigraphy revealed no cardiac sympathetic nerve dysfunction. Our case suggests a possible nigrostriatal presynaptic dopaminergic involvement in diabetic chorea.

We present a 64-year-old man with subacute left-side dominant bilateral choreic movement (diabetic chorea) evaluated using a combination of dopamine transporter SPECT, 18F FDG PET, 99mTc ethylcysteinate dimer (99mTc ECD) SPECT, and 123I metaiodobenzylguanidine (MIBG) scintigraphy. We diagnosed him with diabetic chorea because of poorly controlled diabetes mellitus (HbA1c 13%-18%) and brain MRI showing pathognomonic hyperintensity on T1-weighted imaging in the bilateral caudate nucleus and putamen and right-side external segment of the globus pallidus (A). No significant abnormality on T2- (B) and T2*-weighted images (C) was found in the corresponding area. No significant old infarction or other differential diagnoses for chorea were identified.[1] Dopamine transporter SPECT showed bilaterally and right-side dominant reduced 123I ioflupane binding in the caudate nucleus and putamen (D). The specific binding ratio[2] was 1.22 on the right and 1.36 on the left side (ELEGP was used as a collimator, and no scatter correction or attenuation correction was applied). The asymmetry dopamine transporter SPECT in diabetic chorea index (AI) of ioflupane binding was 10.7%, revealing a decline predominantly on the right side. This was consistent with the contralateral dominance of the chorea. No confounding medication for the evaluation with dopamine transporter SPECT was identified.[3] Brain 18F FDG PET revealed decreased glucose metabolism (E) in the corresponding area, similar to the dopamine transporter SPECT, suggesting regional dysfunction in the bilateral striatum. There was no significant left-to-right difference in striatal 18F FDG PET uptake, with an AI of 2.7%. 99mTc ECD SPECT revealed reduced brain perfusion in the bilateral caudate nucleus, putamen, and thalamus (F). 123I MIBG scintigraphy showed no reduction in the H/M ratio, with 4.95 in the early phase and 5.03 in the late phase (G, late phase). We assumed that a low accumulation in the mediastinum caused this high H/M ratio. Treatment with dopamine antagonist and blood glucose control relieved most choreic symptoms within 4 weeks, and we are now successfully reducing his dopamine antagonist dose. Reduced glucose metabolism was found in the bilateral putamen and caudate nucleus in the 18F FDG PET in our patient, suggesting regional striatal dysfunction. This was consistent with earlier studies on diabetic chorea.[4-7] Several theories regarding the underlying pathology of diabetic chorea have been proposed, including petechial hemorrhage,[7] metabolic abnormality because of hyperglycemia,[5,7] patchy striatal necrosis associated with vasculopathy,[6] and transient ischemia.[7] No conclusion has been reached to date. The only earlier report using dopamine transporter SPECT with hyperglycemic hemichorea-hemiballismus[8] revealed decreased 123I ioflupane binding in the striatum as was observed in our case. Cardiac imaging with 123I MIBG scintigraphy in our case revealed normal 123I MIBG uptake by the cardiac sympathetic nerve, suggesting that coexisting Parkinson’s disease, Lewy body disease, diabetic sympathetic nerve dysfunction, or heart failure were unlikely. This suggests nigrostriatal dopaminergic involvement: presynaptic neuronal terminal dysfunction, reduced density of nerve terminals, or reduced density of dopamine transporter is conceivable.[8,9]