Dopamine D2 receptor SPECT in corticobasal syndrome and autopsy-confirmed corticobasal degeneration.

Abstract Background Corticobasal degeneration (CBD) is a rare neurodegenerative disorder characterized by tau-positive neuronal and glial lesions in the cortex and striatum with neuronal loss in cortical regions and in the substantia nigra. Striatal dopamine D2 receptor binding in autopsy-confirmed CBD has not been studied before. Methods We performed D2 receptor single photon emission computerized tomography using 123 I-IBZM in nine patients with a clinically diagnosed corticobasal syndrome (CBS) and on ten healthy controls. Two of the patients subsequently came to autopsy and were diagnosed with CBD. Results Overall striatal D2 receptor binding was preserved in 8/9 patients, but more asymmetric than in controls. Overall striatal binding in pathologically confirmed CBD was reduced in one case and normal in the other, and was lower contralateral to the clinically more affected side in both. Conclusion This first study on D2 receptor imaging in autopsy-confirmed CBD demonstrates that loss of postsynaptic striatal neurons in CBD is a variable finding. Given the heterogeneity of our findings in pathology-confirmed cases, D2 receptor imaging seems to be of little practical value in the diagnostic workup of patients with CBS.