A surgical instrument for treating body tissues through narrow body passages employs an elongated cantilevered beam having a proximal end supported in a rigid block and a narrower distal end extendable through the narrow passages. One or more piezoelectric actuators are fixed to the beam surface and energized from an AC source provided by an electrical excitation system through electrodes interspersed with the piezoelectric actuators to produce oscillatory motion of the beam distal end in multiple modes of movement.