Objective When patients take
neuroleptics, the distinction between
Parkinson's disease (PD) and drug-induced
parkinsonism (DIP) based solely on clinical features can become difficult. At present,
123I-FP-CIT SPECT (DAT-SPECT) and 123I-metaiodobenzylguanidine (
MIBG) myocardial scintigraphy are widely used to supplement the differential diagnosis of
parkinsonism. This study assessed the clinical symptoms and neurological findings in the patients suspected of having DIP based on DAT-SPECT findings. Methods Twenty-three patients (11 men, 12 women, age: 52-81 years old) presenting with DIP were recruited. All patients underwent neurological examinations, including brain magnetic resonance imaging and DAT-SPECT. Patients who showed abnormal DAT-SPECT results underwent
MIBG myocardial scintigraphy. Results Eleven patients showed a reduction in the
ligand uptake on DAT-SPECT (DAT-positive group), and nine of these patients showed a low delayed heart-to-mediastinum (H/M) ratio on
MIBG myocardial scintigraphy. The remaining 12 patients showed normal results on DAT-SPECT (DAT-negative group). All patients in the DAT-positive group had asymmetric motor symptoms, whereas only 4 in the DAT-negative group exhibited this clinical feature (p=0.001). A detailed medical history showed that 7 of the 11 patients in the DAT-positive group had
prodromal symptoms for PD. However, only 1 patient in the DAT-negative group exhibited these symptoms (p= 0.009). Although two patients in the DAT-negative group showed poor improvement, they showed a normal H/M ratio on
MIBG and no response to
levodopa. Conclusion The patients in the DAT-positive group might have
prodromal symptoms that were worsened by
neuroleptic drugs. The results of detailed history-taking and neurological findings seem to indicate cases of compromised dopaminergic transmission before the administration of
neuroleptic drugs.