NEFL and Parkinson disease: However, clinical observations have shown that NfL levels are significantly higher in patients with atypical parkinsonism such as progressive supranuclear palsy, multiple system atrophy and corticobasal degeneration with neurodegeneration and significant involvement of myelin axons than in patients with PD.[34] At present, blood NfL detection has been widely used in the study of various neurological diseases.