Sunday, June 12, 2011

Outcomes among natalizumab patients acquiring PML

Vermesch P et al.  Clinical outcomes of natalizumab - associated progressive multifocal leukoencephalopathy.  Neurology 2011; 76:1696-1704

Authors analyzed 35 patients with PML related to natalizumab.  25 survived.  Survivors had lower age and EDSS on mean, and shorter time to diagnosis of PML.  86 % had unilobar or multilobar disease on initial PML brain MRI, whereas 70 percent of fatal cases has widespread disease on MRI.  Disability scores (Karnofsky scale) among survivors was highly variable.  16/36/48 % respectively had mild, moderate or severe disability.

Almost all patients withdrawn from natalizumab got IRIS and were treated with i-c corticosteroids, in addition to plasma pheresis to removed natalizumab.  They also received mirtazepine or mefloquine due to in vitro studies showing an effect on replication. 

Tables show much less nonfatal PML in US v. Europe.  Rate of nonfatal to fatal PML was, US: 3:8 in Europe 22:2.  This is not discussed but I wonder if more nonfatal PML slips through cracks in US  and is either not diagnosed or reported. 

Posterior fossa PML was rare.  Most patients had enhancing lesions.

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