Abstract: Device and method for monitoring evoked potentials and/or electroencephalograms including a novel unipolar spiral coil electrode. The unipolar electrode includes a user holder member formed of non-conductive material and having an outside surface adapted to be grasped by the physician's fingers. A spiral coil formed of a conductive material and having a pointed or beveled tip extends forward from the user holder member. The coil is directly attached to the user holder member such that when the user holder member is grasped by the physician's fingers, pressed against the patient's skin and rotated, the tip pierces the patient's skin and the spiral coil is twisted through the epidermis to a distance sufficient to secure the user holder member to the patient but not great enough to pierce the underlying bone. To assist in manipulating the user holder member, the user holder member on its outer surface includes a friction increasing device such as a pair of projecting ears, a knurled surface, or a knob.

Abstract: A spinal stabilization device positionable between separated but neighboring vertebral bodies to stabilize a spinal column which has been rendered unstable by disease. The device includes a vertebral body prosthesis containing at least one pair of oppositely disposed anchoring pins which are advanced out of the prosthesis into the abutting vertebral bodies to secure the prosthesis to and between them. On its anterior side the prosthesis has an opening communicating with the pins inside the prosthesis. A wrench is inserted into the opening until it engages the pair of pins, and then the wrench is rotated to advance the pins into the abutting vertebral bodies. Detent pins bias the anchoring pins against the wrench and lock the anchoring pins in place when in their fully extended anchoring positions. Spacer members can be attached to the ends of the prosthesis thereby elongating it to accommodate separations between neighboring vertebral bodies of varying dimensions.