An electrosurgical system preferably used for denervation procedures of nerve tissue has a control unit and a pluggable electrode assembly. The electrode assembly has a preferably disposable cannula and a preservable supply electrode assembly. The cannula has a tubular body that projects axially from a preferably pointed distal end for piercing tissue to a proximal end engaged to a first coupling assembly of the cannula. The body carries a first contact exposed directly to the nerve tissue and connected electrically to a terminal of the first coupling assembly. The supply electrode assembly has a second coupling assembly and a supply electrode that projects axially and removably into a through-bore of the body when the tool is in an operating state. The second coupling assembly carries a terminal that abuts the first coupling assembly when the coupling assemblies are mated. Preferably the supply electrode carries a temperature sensor for temperature measurement of the targeted tissue and processing by the control unit. Preferably, the electrode assembly also includes a stylet having a rod that fits into the through-bore of the body when the supply electrode assembly is removed and the tool is in a tissue penetrating state.