Abstract: An improved stereotactic instrument for precise insertion of an electrode or a biopsy needle into the brain is designed for use with a computed tomographic (CT) scanner and does not require scanner software modification or complicated calculations to transfer the scanner coordinates of a desired brain location to the instrument. The instrument is based on a modified rectangular Gouda frame which can be temporarily attached to the CT scanner table by mounting plates that can be adjusted relative to one another until the frame is precisely aligned to the CT scanner zero reference plane. The frame is then affixed to the patient and after a plurality of CT scans are taken to establish the coordinates of the desired brain location, the patient and frame are detached from the CT table and moved to the operation room where coordinate arms and a electrode/needle holding arc are placed on the frame. The target coordinates obtained from the CT scanner can then be set directly on the coordinate arms of the frame.

Abstract: A stereotactic instrument for precise insertion of an electrode in the brain for treatment of certain nervous system disorders, such as Parkinson's disease. A rectangular frame surrounds the head and is supported by four pins pressed against the skull. The front and back segments of the frame support radio-opaque vertical markers for alignment with the midline of the brain. The left and right segments each support a pair of adjustable radio-opaque markers for alignment with the anterior and posterior commissures of the brain. Adjustment is by turning knobs connected to a rod and gear system. Bridges between anterior and posterior markers parallel a reference line between the commissures of the brain's third ventricle. Adjustable brackets on the bridge support an arc bearing an electrode carrier.