Onset age and severity of motor impairment are associated with reduction of myocardial ¹²³I-MIBG uptake in Parkinson's disease

Objectives: To elucidate the factors associated with severity of cardiac sympathetic nerve involvement in idiopathic Parkinson's disease (PD). Methods: ¹²³I-metaiodobenzylguanidine uptake was examined in 88 patients with PD. The ratio of the uptake in the heart (H) to that in the mediastinum (M) (the H/M ratio) was calculated and correlated with age at onset, age at examination, and disease severity and duration. Twenty five healthy people were also examined as a control. Results: There was a mild but significant negative correlation between H/M ratio and age at onset (early, r = -0.33, p = 0.002; delayed, r = -0.34, p = 0.001) and between Hoehn and Yahr (H-Y) stage (early, r = -0.30, p = 0.006; delayed, r = -0.32, p = 0.003). There was no significant correlation between disease duration and H/M ratio. When patients with PD were classified into four subgroups on the basis of age at onset (> 62 or < 62 years) and disease severity (H-Y > III or H-Y < II), the median H/M ratio of the older and more severe group was significantly lower than that of the younger and less severe group (p = 0.005). Conclusion: This study suggests that late onset, high severity PD is associated with myocardial sympathetic dysfunction.