We sought to examine the practical utility of radiologic markers of progressive supranuclear palsy (PSP) by investigating whether these markers could distinguish between patients with PSP and those with Parkinson's disease based on imaging obtained in a typical clinical setting, not in a prospective research environment. Furthermore, we provide a simple protocol that non-research neurologists can follow to obtain markers of PSP. 

Early diagnosis of PSP can be difficult. In the early stages of this disease, patients often present to the clinic with nonspecific cognitive complaints that may be confused with Alzheimer’s disease or other dementias. Additionally, as preliminary motor symptoms arise, distinguishing between PSP and other parkinsonian disorders can be a challenge. In patients with these disorders, imaging has shown promise as a method to augment accurate diagnosis.

This retrospective study included 13 patients with progressive supranuclear palsy and 13 patients with Parkinson's disease who were followed for either condition at our institution at the time of the study and who had MRI records available. Patients were selected without regard to type of imaging obtained. All diagnoses were confirmed by a trained movement disorders specialist using validated diagnostic criteria. Groups were matched for age and disease duration at the time of scanning. MRI records were retrospectively obtained, and image analysis was performed by investigators blinded to disease classification. Midbrain area, midbrain to pons area ratio, midbrain anterior-posterior diameter, and MR parkinsonism index were calculated for each patient.

All established measures of identifying progressive supranuclear palsy (midbrain area, midbrain to pons area ratio, midbrain anterior-posterior diameter, and MR parkinsonism index) were significantly different between patients with progressive supranuclear palsy and those with Parkinson's disease.