Decreased striatal monoaminergic terminals in multiple system atrophy detected with positron emission tomography

We examined the density of striatal presynaptic monoaminergic terminals, us ing a ligand for the type 2 vesicular monoamine transporter, (+)-[C-11] dih ydrotetrabenazine, with positron emission tomography in 7 normal control su bjects, 8 multiple system atrophy (MSA) patients with predominantly parkins onian features (MSA-P), 8 MSA patients with principally cerebellar dysfunct ion (MSA-C), and 6 sporadic olivopontocerebellar atrophy (sOPCA) patients. The findings were correlated with the results of neurological evaluations a nd magnetic resonance imaging studies. Specific binding was significantly r educed in the putamen of all patient groups in the order MSA-P < MSA-C < sO PCA, compared with controls, Mean blood-to-brain ligand transport (K-1) was significantly decreased in the putamen of all patient groups and in the ce rebellar hemispheres of MSA-C and sOPCA but not MSA-P groups, compared with controls. Significant negative correlations were found between striatal bi nding and the intensity of parkinsonian features and between cerebellar K-1 and the intensity of cerebellar dysfunction. The results suggest fundament al differences between MSA-P and MSA-C groups reflecting differential sever ity of degeneration of nigrostriatal and cerebellar systems in these two fo rms of MSA, The findings also show that some sOPCA patients have subclinica l nigrostriatal dysfunction and are at risk of developing MSA with disease progression.