Neurofilament light

Neurodegenerative parkinsonian disorders were historically divided into 2 major groups based on their clinical picture, treatment response, and prognosis. One group encompassed Parkinson disease (PD), characterized at onset by usually asymmetrical extrapyramidal motor symptoms showing a marked and sustained response to levodopa, and subsequent slow motor decline over time. The other group included the much rarer atypical parkinsonian disorders (APDs), including multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), with features signaling early autonomous, pyramidal, or cortical involvement, poor motor response to levodopa, and a much more rapid functional decline and higher mortality than usually seen in PD.1