@article {Wijburg44, author = {Martijn T Wijburg and Clemens Warnke and Frederik Barkhof and Bernard M J Uitdehaag and Joep Killestein and Mike P Wattjes}, title = {Performance of PML diagnostic criteria in natalizumab-associated PML: data from the Dutch-Belgian cohort}, volume = {90}, number = {1}, pages = {44--46}, year = {2019}, doi = {10.1136/jnnp-2018-318261}, publisher = {BMJ Publishing Group Ltd}, abstract = {Objective To test the current progressive multifocal leukoencephalopathy (PML) diagnostic criteria by applying them to patients previously diagnosed with natalizumab~(NTZ)-associated~PML in a real-world clinical setting.Methods Patients from the Dutch-Belgian NTZ-PML cohort (n=28) were reviewed at the time of first diagnostic work-up and during follow-up, using the PML diagnostic criteria as proposed in a consensus statement from the American Academy of Neurology.Results At first diagnostic work-up, 18 patients (64.3\%) met the criteria for high diagnostic certainty for PML ({\textquoteleft}definite PML{\textquoteright} or {\textquoteleft}probable PML{\textquoteright}). During follow-up, this increased to 20 patients (71.4\%) as JC~virus~DNA was detected in cerebrospinal fluid~of two additional patients. Nonetheless, 28.6\% of patients were still classified as {\textquoteleft}possible PML{\textquoteright} or {\textquoteleft}not PML{\textquoteright} (6~(21.5\%) and 2~(7.1\%)~patients, respectively) despite a very high suspicion for PML based on lesion evolution and signs of PML-immune reconstitution inflammatory syndrome on MRI, and development of compatible symptoms.Conclusions The current case definition of PML has low sensitivity for diagnosis of NTZ-PML in a real-world clinical setting in which MRI is frequently used for PML screening. This may delay diagnosis and appropriate management of PML, and may complicate a valid estimation of PML incidence during NTZ therapy.}, issn = {0022-3050}, URL = {https://jnnp.bmj.com/content/90/1/44}, eprint = {https://jnnp.bmj.com/content/90/1/44.full.pdf}, journal = {Journal of Neurology, Neurosurgery \& Psychiatry} }