Abstract: A method is disclosed for treating a neurodegenerative disorder comprising the steps of surgically implanting a catheter so that a discharge portion of the catheter lies adjacent a predetermined infusion site in a brain, and discharging through the discharge portion of the catheter a predetermined dosage of at least one substance to the infusion site of the brain, the at least one substance capable of altering a nucleotide in a DNA sequence of a gene to convert a codon in a protein-coding region of the gene into a stop codon in the brain, whereby neurodegeneration in the brain is reduced. In a preferred embodiment, the at least one substance is a mutational vector, for example, a RNA/DNA chimeric mutational vector. The disclosed invention provides a method for treating neurodegenerative disorders such as Huntington's disease, spinocerebellar ataxia type 1, type 2, type 3, type 6, and/or type 7, spinobulbar muscular atrophy (Kennedy's disease), and/or dentatorubral-pallidoluysian atrophy (DRPLA).