Objective: The aim of this study was to investigate whether non-motor manifestations of Parkinson’s disease (PD) differ between patients with normal and abnormal myocardial metaiodobenzylguanidine (MIBG) uptake.

Background: Reduction of MIBG uptake has been observed in almost all patients with PD and it was associated with hyposmia, orthostatic hypotension and rapid eye movement sleep behavioral disorders (RBD). In contrast, a subgroup of patients with PD who have normal MIBG uptake have been reported to have milder disease and preserved cognition compared to that of those with lower MIBG. 

Methods: Among 160 de novo cases of PD, 44 had normal MIBG uptake. Twelve candidate non-motor features were evaluated using questionnaires and laboratory tests. 

Results: Patients with decreased MIBG uptake had more constipation, RBD, cognitive impairment, hyposmia and orthostatic hypotension than did those with normal MIBG uptake. On linear regression analysis, orthostatic hypotension, olfactory function and probable RBD were significantly associated with MIBG uptake in PD. The principal component analysis showed that the group with normal MIBG was not associated with non-motor impairments.

Conclusions: These results suggest that PD patients with normal MIBG scans have a relatively low disease burden compared to those with abnormal MIBG. Fewer synuclein pathologies in the myocardia and sympathetic ganglia in PD with preserved MIBG uptake might be associated with lower threshold patterns of Braak synuclein pathology for non-motor manifestations compared to those with decreased MIBG. 

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MDS Abstracts - https://www.mdsabstracts.org/abstract/normal-heart-in-parkinsons-disease-is-this-a-distinct-clinical-phenotype/