#$%^&*AU2017202216A120170427.pdf#####ABSTRACT The present invention provides, among other things, compositions and methods for CNS delivery of lysosomal enzymes for effective treatment of lysosomal storage diseases. In some embodiments, the present invention includes a stable formulation for direct CNS intrathecal administration comprising a heparan N-sulfatase (HNS) protein, salt, and a polysorbate surfactant for the treatment of Sanfilippo Syndrome Type A.