An instrument set for the microinvasive treatment of stenoses of the spinal canal and/or other constrictions of the spinal canal, comprisinga microinvasive access tube (1) having a distal end insertable into the bodyan ablation device (2) having an ablation head (21) which can be accommodated in the access tube (1) and which can be directed out of the access tube (1) at the distal end and brought into at least one working positiona screening element (31) for screening the ablation head (21) in relation to the dura which can be accommodated in the access tube (1) and which can be directed out of the access tube (1) at the distal end and brought into at least one working position in which the screening element (31) laterally protrudes above the access tube (1).
