At 3 months , the reduction in dystonia severity was significantly greater with neurostimulation ( -51 points [ SD 51 ] , 95 % CI -70 to -35 ) than with sham stimulation ( -13 [ 24 ] , -22 to -04 , p = 00024 ; mean between-group difference 38 points , 18 to 58 ) in the intention-to-treat population .