CSTB and progressive myoclonus epilepsy: However, indirect evidence has been found from two types of studies: (i) the attempt to determine the biological mechanism that underlie the ketogenic diet (an alternative therapy for refractory epilepsy); and (ii) the analysis of the effect of Cystatin B in regulating redox in a model of progressive myoclonus epilepsy (a form of epilepsy with a high frequency of refractoriness).