“…Intrathecal enzyme replacement therapy (ERT) holds promise as a treatment for the central nervous system manifestations of lysosomal storage diseases, since treatment via the cerebrospinal fluid represents a potential method of delivering recombinant enzyme across the blood-brain barrier. All intra-cerebrospinal fluid ERT studies in mice have reported improved function, and reduced neuropathology has also been described in the brain of dog models (MPS I Dickson et al, 2007), MPS IIIA (Hemsley et al, , 2008(Hemsley et al, , 2009). However, several questions remain regarding this approach, in particular which route of injection (ventricular, cisternal or lumbar) provides the most widespread distribution of enzyme in brain parenchyma; is bolus or sustained delivery of enzyme via an osmotic pump device preferable; and, finally, what is the optimal frequency of administration for each condition?…”