The potential role of the cardiac MIBG scan in differentiating the drug-induced Parkinsonism from Parkinson’s disease

INTRODUCTION: Considering the difficulties of differentiating Parkinson’s disease (PD) from drug-induced Parkinsonism (DIP) in patients receiving antipsychotics, developing robust diagnostic tools is essential. Herein, we used the metaiodobenzylguanidine (MIBG) scan to assess its diagnostic accuracy for this purpose. METHODS: 44 DIP patients and 32 patients with PD as controls were enrolled. All the participants underwent a cardiac (131)I-MIBG scan. Statistical analysis was conducted to determine the significance of the results, and accuracy analyses were conducted to calculate the related sensitivity and specificity of the MIBG scan. RESULTS: The mean age of PD and DIP groups were 62.6 ± 5.9 and 51.5 ± 10.8 years, respectively. The mean duration of drug consumption in the DIP group was 52.2 ± 29.4 days (the mean interval between drug initiation and DIP onset was 28.5 ± 20.5). Symptoms relief occurred 40 ± 24.2 days after drug discontinuation. In the PD group, 15.6% showed negative and 84.4% positive results on the MIBG scan. In the DIP group, 86.4% were negative, and the remaining were positive. The difference in MIBG uptake between the two groups was statistically significant (P-value < 0.001). The sensitivity and specificity of the MIBG scan were 84.4% (CI: 84.0–84.8) and 86.36% (CI: 86.0–86.7) for the diagnosis of PD, respectively. CONCLUSION: Our results indicated more positive MIBG scans in the PD group than the DIP. Also, the MIBG scan’s sensitivity and specificity in differentiating the PD are acceptable. Future works should assess these findings and the role of the MIBG scan in prognosis assessment of DIP and better allocation of the patients to related disciplines.