A microdrive apparatus useful in human stereotactic surgery is disclosed. Such apparatus permits safe and accurate placement of a surgical instrument, such as a cannula, into a portion of the central nervous system, e.g. the brain and spinal cord, of a patient by simple mechanical operation....http://www.google.se/patents/US5871487?utm_source=gb-gplus-sharePatent US5871487 - Microdrive for use in stereotactic surgery
