Electrically insulated surgical needle assembly

A surgical tool for penetrating tissue and monitoring the proximity of neural elements, comprising:

• a needle assembly extending along a longitudinal axis, said needle assembly comprising:
• a stylet including an electrically conductive portion near a pointed distal end, a shaft extending proximally from said distal end providing a conductive path to a proximal extension of said stylet;
• a cannula including an electrically conductive portion and an insulated outer surface area around said electrically conductive portion extending along a length of said cannula wherein said pointed distal end of said stylet projects distally from said insulated surface area when said stylet is positioned in said cannula;
• a handle assembly attachable near said proximal end of said needle assembly comprising:
• an electrically insulated outer surface area;
• an electrically conductive area internal to said electrically insulated surface area and engageable with said proximal extension of said stylet;
• said handle assembly including a gripping portion having a major dimension at least 50% greater than a minor dimension, said major and minor dimensions being measured orthogonally to said longitudinal axis and to one another;
• and
• an electrical lead extending from said electrically conductive area through said handle assembly along said major dimension, wherein said handle assembly includes a handle body having a bore extending along said major dimension from a lateral outer surface of said handle body to a receptacle aligned along said longitudinal axis of said needle assembly when said handle assembly is engaged to said needle assembly, said lead extending through said bore, and the handle assembly further comprising a housing positioned in said bore, said housing defining a trough extending along a length of said housing with said trough opening along one side of said length of said housing, said housing further including opposite lateral protrusions projecting into said trough to secure a cable portion of said lead to said housing in said trough and an axial protrusion extending into said trough that secures said cable through said opening along said one side of said housing against an inner surface of said handle body that defines said bore, wherein said cable portion includes an electrical contact extending from the cable portion into said receptacle within said handle assembly and said proximal extension of said stylet fits inside said receptacle in said handle assembly and is electrically coupled to said electrical contact.