An elderly male,case of Hep c (genotype 1) presented with very high viral load. He was started with triple regimen of IFN, Rofosbuvir and Ribavirin. On day2, pt had severe GI intolerence, especially after taking Sofosbuvir and he has stopped the medicine. But gradually he started having severe dysarthria and headache, CT brain was showing white matter cerebral edema/post reversible encephalopathy. Presently, he is still on IFN plus Ribavirin (week 4), but his neurological symptoms are still there, although GI symptoms are much better. An MRI brain was advised, possibly will get report by tomorrow.....Now, what may be the cause of his neurological symptoms????