Two distinct degenerative types of nigrostriatal dopaminergic neuron in the early stage of parkinsonian disorders

Highlights

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  Integrative neuroimaging analysis characterized nigrostriatal neuron degeneration.

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  Correlation of NRC _SN with SBR clearly differed from that of PSP with CBS.

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  In MSA-P, interhemispheric laterality of SBR coincided with putamen atrophy.

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  No significant correlation occurred between NRC _SN and SBR in MSA-P.

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  Parkinsonian disorders are divisible into two groups based on NRC _SN-SBR correlation.

Abstract

Introduction

The present study characterized the degeneration of nigrostriatal dopaminergic neurons in the early stages of parkinsonian disorders using integrative neuroimaging analysis with neuromelanin-sensitive MRI and ¹²³I-FP-CIT dopamine transporter (DAT) SPECT.

Methods

Thirty-one, 30, and 29 patients with progressive supranuclear palsy (PSP), corticobasal syndrome (CBS) with abnormal specific binding ratio (SBR) in either hemisphere (mean ± 2SD), and parkinsonism-predominant multiple system atrophy (MSA-P), respectively, were enrolled. Neuromelanin-related contrast (NRC) in the substantia nigra (NRC _SN) and locus coeruleus (NRC _LC) and the SBR of DAT SPECT were measured. All the patients underwent both examinations simultaneously within five years after symptom onset. After adjusting for interhemispheric asymmetry on neuromelanin-related MRI contrast using the Z-score, linear regression analysis of the NRC _SN and SBR was performed for the most- and least-affected hemispheres, as defined by the interhemispheric differences per variable (SBR, NRC _SN, standardized [SBR + NRC _SN]) in each patient.

Results

Although the variables did not differ significantly between PSP and CBS, a significant correlation was found for CBS in the most-affected hemisphere for all the definitions, including the clinically defined, most-affected hemisphere. No significant correlation was found between the NRC _SN and SBR for any of the definitions in either PSP or MSA-P.

Conclusion

Together with the findings of our previous study of dementia with Lewy bodies (DLB) and Parkinson’s disease (PD), the present findings indicated that neural degeneration in the disorders examined may be categorized by the significance of the NRC _SN-SBR correlation in PD and CBS and its non-significance in DLB, PSP, and MSA-P.