Abstract: An electrosurgical instrument is provided for the treatment of tissue, the instrument (3) comprising an instrument shaft (14) having a longitudinal axis, a suction lumen (24) extending at least partially along the instrument shaft, and an electrode assembly at one end of the shaft. The electrode assembly comprises at least one tissue treatment electrode (16), the tissue treatment electrode having an end face (17) and at least one side face (18). The tissue treatment electrode includes a plurality of apertures in communication with the suction lumen, at least one aperture (19) being present in the end face and at least one aperture (20) being present in the side face.

Abstract: An electrosurgical instrument is provided for the treatment of tissue in the presence of an electrically-conductive fluid medium. The instrument comprises an instrument shaft (10), and a tissue treatment electrode (12) at the distal end of the shaft for electrosurgically excising tissue pieces at an operation site. The tissue treatment electrode (12) is cyclically movable relative to the distal end of the shaft (10). Threshold control means are provided for controlling the power threshold for vaporisation of the electrically-conductive fluid medium at the tissue treatment electrode (12).