Reconsidering brain MRI in apparently classical Parkinson's disease: one-time structural imaging for every patient?

Expert opinion, based on a careful medical history and detailed neurological examination, remains the gold standard to diagnose Parkinson's disease (PD). Neuroimaging is deemed unnecessary in those presenting with a characteristic phenotype. We encountered two patients in whom our expert clinical opinion, namely not to scan, was 'overruled' because structural brain imaging had been performed elsewhere. The MR scans unexpectedly showed an underlying cause for the parkinsonian symptoms, with unequivocal therapeutic implications. Neither patient had any unambiguous non-motor symptoms. Stimulated by these two cases, we present a nuanced view on the possible indications for brain MRI in people with apparently classical motor PD. We propose to count the absence of any unambiguous non-motor symptoms as a double (rather than single) red flag, thus requiring this to be countered by two supportive signs, and suggest lowering the threshold for brain scanning in such patients.