The importance of this study can be expressed by the high incidence of Parkinsonism and the need for accurate and rapid diagnosis and the growing interest in non motor signs. The differential diagnosis of Parkinsonism mainly considers clinical findings, however, imaging tests and other markers may be essential tools for a quick diagnosis.

We evaluated 350 medical records of patients from a tertiary neurology service. We included patients examined by the same neurologist, and complete records, including detailed neurological examination and completed investigation scales. After a thorough review, 153 medical records were included. We used visual or qualitative evaluation; with normal or abnormal, symmetrical or asymmetrical results, with discrete, moderate, marked, and severe degrees of impairment. 

A direct relationship was found between severity in reduced SPECT-TRODAT in the group of patients with synucleinopathies (rho = 0.258, p = 0.005). Changes in SPECT-TRODAT had high correspondence with clinical changes (symmetry) in all types of parkinsonism. Regarding the correspondence of the exam with predominantly bilateral or unilateral impairment, there was a difference between patients with synucleinopathies (p= 0.041) and between this group and patients with secondary parkinsonism (p< 0.0001), which showed higher correspondences when the cases had a bilateral clinical presentation. The exam was instrumental in differentiating secondary parkinsonism from synucleinopathies. In the group of drug-induced parkinsonism, younger people were the ones who showed the greatest reductions in radiotracer binding. In this group, the presence of non-motor signs resulted in examinations with greater reductions in radiotracer binding.