Tissue interface detector for ventriculography and other applications

Claim 1

A DETECTOR FOR NEUROSURGICAL PROCEDURES COMPRISING A CANNULA ASSEMBLY HAVING A SUBSTANTIALLY CYLINDRICAL BODY MEMBER WITH AN ENLARGED INTERNAL BORE TERMINATING IN A SUBSTANTIALLY FRUSTO-CONICAL BORE, A HOLLOW VENTRICULAR NEEDLE MEMBER SECURED TO AND PROTRUDING INTO THE FRUSTOCONICAL SECTION OF THE BORE IN COMMUNICATING RELATIONSHIP THEREWITH, A CAP MEMBER ADAPTED TO ENCLOSE THE CYLINDRICAL END OF THE CANNULA AND TO BE SECURED THERETO, AN INSULATING MEMBER SUPPORTED WITHIN THE CLOSED END PORTION OF THE SAID CAP, MEANS TO ESTABLISH AN ELECTRICAL CONNECTION THROUGH THE INSULATING MEMBER AND THE CAP TO AN EXTERNAL CIRCUIT, MEANS TO CONNECT THE CAP MEMBER ALSO TO AN EXTERNAL CIRCUIT, A SECOND INSULATING MEMBER ADAPTED TO BE REMOVABLY POSITIONED WITHIN THE CYLINDRICAL PORTION OF THE CANNULA AND TELESCOPICALLY RECEIVED WIT''IN THE SAID CAP MEMBER, AN ELECTRODE ELEMENT SUPPORTED WITHIN THE LASTNAMED INSULATING MEMBER AND EXTENDING OUTWARDLY THEREFROM IN A DIRECTION INTERNALLY OF THE HOLLOW VENTRICULAR NEEDLE AN INSULATING MEMBER SURROUNDING SAID ELECTRODE FOR THAT PORTION THEREOF WHICH IS ADAPTED TO EXTEND THROUGH THE VENTRICULAR NEEDLE TO ELECTRICALLY INSULATE IT FROM THE NEEDLE THE CYLINDRICAL BODY AND THE CAP, MEANS PROVIDED BY THE CYLINDRICAL CANNULA MEMBER FOR SUPPORTING THE LASTNAMED INSULATING ELEMENT AND THE ELECTRODE MEMBER SUPPORTED THEREBY WITHIN THE CYLINDRICAL PORTION OF THE CANNULA SO AS TO BE TIGHTLY FITTED THEREIN AND YET REMOVABLE THEREFROM, AND MEANS FOR ESTABLISHING AN ELECTRICAL CONNECTION BETWEEN THE ELECTRODE MEMBER SUPPORTED BY THE SECOND-NAMED INSULATING MEMBER AND THE ELECTRICAL CONNECTION THROUGH THE FIRST INSULATING MEMBER SUPPORTED BY THE CAP MEMBER, WHEREBY THE CANNULA AND VENTRICULAR NEEDLE ARE ADAPTED TO PROVIDE ELECTRODE ELEMENTS FOR DETERMINING PENETRATION OF THE INSTRUMENT THROUGH AN INTERFACE BETWEEN TWO TYPES OF TISSUE AND WHEREBY THE VENTRICULAR NEEDLE, WITH THE CAP AND ELECTRODE ASSEMBLY REMOVED, IS ADAPTED TO PROVIDE A PASSAGEWAY FOR BI-DIRECTIONAL PASSAGE FROM AND TO THE PENETRATED REGION OF THE INTERFACE.