Follow-up study of cardiac ¹²³I-MIBG scintigraphy in idiopathic REM sleep behavior disorder.

BACKGROUND

Cardiac (123) I-metaiodobenzylguanidine ((123) I-MIBG) uptake in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is markedly reduced, as in Parkinson's disease (PD).

METHODS

We performed (123) I-MIBG scintigrams on patients with iRBD and PD. After the initial (123) I-MIBG scintigram, we retested subjects after a mean of 2.8 years.

RESULTS

The delayed heart-to-mediastinum (H/M) ratio of cardiac (123) I-MIBG uptake was not significantly reduced between the first and second study in either group (P = 0.050, P = 0.091, respectively). Follow-up imaging revealed a mean decline of 4.21 ± 9.06% or 6.40 ± 19.02% in the delayed H/M ratio in those with iRBD or PD, respectively.

CONCLUSIONS

The (123) I-MIBG uptake findings might indicate progression early in the course of iRBD or PD, but the progression is heterogeneous and independent of development of motor symptoms.