59 yo with weakness and mild dysarthria who is currently an inpt at a rehab hospital and had imaging requested prior to discharge as the sx’s were getting worse.
Slide #1: Axial FLAIR sequence.
Slide #2: Lesion as seen in a diffusion weighted sequence.
Slide #3: Same lesion seen in a T1 weighted post contrast axial sequence.
Slide #4: Axial FLAIR sequence. Some additional hx: Prior to discharge, MS exacerbation was to be excluded. Imaging of this pt’s MS lesions are shown here.
Slide #5: FLAIR axial image of the same pt in April 2012. He was on Tysabri at the time. Tysabri is a humanized monoclonal antibody directed against the cellular adhesion molecule alpha4-integrin. This reduces egress of lymphocytes into the CNS reducing inflammation associated with MS plaques. Notice the lack of a right frontal lobe lesion.
Slide #6: October head CT with new weakness and dysarthria. This scan is 6 wks prior to the brain MRI in Slide #1. Tysabri was d/c’d at this time as clinically it was ineffective. Plasmapheresis (PLEX) was not performed as the head CT was read out as MS with a new right frontal plaque.
Not bx proven, but this is likely a combination of PML/IRIS (immune reconstitution inflammatory syndrome) at this time point and considering the tx hx or lack thereof.
Here is a 2 article review that discusses HIV pt’s and PML with a short segment on the topic of PML in tx’d MS pt’s. By imaging PML and IRIS are indistinguishable, but the time line usu helps (IRIS occurs ~2-3 wks after d/c of natalizumab with PLEX tx or 2-3 mo’s without tx as the drug clears from the pt’s blood stream). PML will usu occur 2-3 yrs after being tx’d with natalizumab (70% of the population carries the JC virus suppressed by an intact immune system). In addition, IRIS usually will enhance and PML usu doesn’t enhance or minimally so along the periphery. There is overlap in their enhancement characteristics and they can coexist simultaneously. Read the first article by clicking here.
MS pt’s with PML often respond to PLEX therapy. IRIS can respond to high dose steroids. It is important to tx IRIS quickly as the rebound immune response can be fatal. This article mentions that MR spectroscopy may be helpful to distinguish between the two.