Cardiac 123I-MIBG scintigraphy as an outcome-predicting tool for subthalamic nucleus stimulation in Parkinson's disease

I-123-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy is a useful tool for differentiating idiopathic Parkinson's disease (PD) from other parkinsonian syndromes, but its prognostic value in PD has not been established. The objective of this study was to clarify the correlation between cardiac MIBG uptake parameters and the outcome in PD patients subjected to the subthalamic nucleus stimulation. We enrolled 31 consecutive PD patients and calculated the heart-to-mediastinum ratio (H/M) and washout rate (WR) based on the activity measured at 15 min (early phase) and 3 h (delayed phase) after the intravenous injection of MIBG (111 MBq). Cardinal motor symptoms and activity of daily living (ADL) were assessed on the Unified Parkinson's Disease Rating Scale (UPDRS) and Schwab and England (S-E) ADL scale, before and 3 months after surgery. Neither early nor delayed H/M correlated with any of the preoperative subscores on the UPDRS or S-E, nor with postoperative outcome. On the other hand, increased WR was a positive predictor for postoperative improvement rate on S-E in medication-off state (p = 0.00003). Also, WR showed a more faint but significant correlation with preoperative levodopa responsiveness on S-E (p = 0.008). Our findings suggest that I-123-MIBG scintigraphy in combination with levodopa-responsiveness evaluation may represent a useful tool for prediction of outcomes in patients subjected to STN stimulation.