“In keeping with the theme of natalizumab-associated PML this case study demonstrates a complication of washing-out natalizumab and letting a competent immune system access to the brain in someone with PML. The anti-viral lymphocytes that were being kept out of the brain by natalizumab flood back in and set-up a severe viral encephalitis. The resulting inflammation and swelling can be fatal, particularly if the PML load is large or is an area that can compromise vital brain functions, i.e. the brain stem. This is why this case needed to be treated with steroids. A confounding factor in PML IRIS could be MS rebound. The latter is the recurrence of MS disease activity that occurs 3-4 months after stopping natalizumab. In someone with PML we assume all the inflammation is due to PML-IRIS, but a substantial amount of it could be MS-related.”
“IRIS TO ANOTHER VIRUS; rolls off the tongue like a line in a limerick.”
Calvi et al. Partial recovery after severe immune reconstitution inflammatory syndrome in a multiple sclerosispatient with progressive multifocal leukoencephalopathy. Immunotherapy. 20146(1):23-8. doi: 10.2217/imt.13.155.
Progressive multifocal leukoencephalopathy (PML) is a rare and severe complication of natalizumab therapy in MSers and it may be accompanied by immune reconstitution inflammatory syndrome (IRIS). Here, we describe a case of abnormally severe IRIS, which occurred 2 months after natalizumab-associated PML in a 38-year-old woman affected by multiple sclerosis. The patient was John Cunningham virus-positive and was treated for 21 months when she developed PML. The subsequent IRIS diffusely afflicted the brain, producing edema and signs of intracranial hypertension (increased pressure within the skull), with a clinically severe form compromising the state of consciousness, requiring intensive care and high-dosage steroid treatment. Nevertheless, she survived and partially recovered. There is still difficulty in differentiating PML progression from IRIS onset and there is not a clear description in the literature about different clinical forms of IRIS, prognostic factors and guidelines to properly treat this complication in order to reduce the residual disability of the patient surviving this treatment complication.