Cardiac Sympathetic Denervation Can Predict the Wearing-off Phenomenon in Patients with Parkinson Disease

Recent studies have suggested that preserved cardiac sympathetic denervation may be associated with a small motor burden in Parkinson disease (PD) and serve as a good marker, which is not associated with other nonmotor symptoms. We sought to investigate whether cardiac sympathetic denervation increases the risk of the early wearing-off phenomenon in PD. Methods: This hospitalbased prospective study enrolled 266 de novo patients with PD who underwent 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy on initial evaluation. The patients visited the outpatient clinic every 2-6 mo and were followed for a minimum of 18 mo from the time they began taking dopaminergic medication. Each patient was assessed for the wearing-off phenomenon on the basis of the clinical assessments and symptom diaries. Clinical events were analyzed from the date of evaluation by 123I-MIBG scintigraphy until the date of the first occurrence of the wearing-off phenomenon, or until the last follow-up date without wearing-off. Results: During a mean follow-up period of 30.4 +/- 14.8 mo, 71 patients developed wearingoff. The wearing-off phenomenon occurred more in patients with decreased 123I-MIBG uptake. A Cox regression analysis revealed that both low 123I-MIBG uptake and early onset age significantly predicted the development of wearing-off. Conclusion: Our study suggests that a reduction in myocardial 123I-MIBG uptake in PD patients may be associated with a subsequent increased risk for the wearing-off phenomenon. Findings strongly support that PD patients with normal cardiac sympathetic innervation might have less involvement of the midbrain dopaminergic circuitry and a concomitant reduced risk for motor complications, such as wearing-off.