Various types of pneumatically driven devices have been used in craniotomy procedures for opening the skull. By contrast, except for some limited cases where a rotating cutter has been used to remove tumors from the central nervous system, only hand tools are commonly used for tumor or tissue removal. A pneumatically-activated probe cutter has been designed for the neurosurgical removal of nervous-system tumors and diseased tissue. The handheld probe-cutter utilizes concentric needles, one reciprocating inside the other. A scalpel-sharp edge on the tip of the inner needle moves in a shearing motion past a stationary port on one side near the distal end of the outer needle. The driving force for the reciprocating motion of the inner needle is provided by a pneumatic power source.