A cutting operation is performed with an apparatus having an elongated sleeve with a port in its distal section. The sleeve is connected to a vacuum source and a rotating shaft is disposed in the lumen of the sleeve. The shaft has a cutting blade at its distal end opposite the port. The blade has two cutting edges, a gear assembly operative to alternately rotate the shaft in a first direction and a second direction about the axis of symmetry of the shaft, and a motor for powering the gear assembly.