Apparatus for dilating bodily tissue and for monitoring neural activity in the dilated bodily tissue

Abstract

An apparatus is provided herein for dilating bodily tissue and for monitoring neural activity in the distracted bodily tissue. In one aspect of the invention, the apparatus includes a first dilator having a tubular body with a distal end, a proximal end, and at least one electrode mounted about a circumference thereof; and, a second dilator having a tubular body of electrically-insulative material, the tubular body having a distal end, a proximal end, and a lumen extending therebetween sized to permit the second dilator to subsequently telescopically slide over the first dilator and come into overlapping coaxial alignment with the first dilator. A discrete window is formed through the tubular body, at or near the distal end, in communication with the lumen. With the second dilator being in overlapping coaxial alignment with the first dilator, the window is located to come into registration with at least one electrode such that, upon rotation of the second dilator relative to the first dilator, the window is positionally adjustable about the circumference of the first dilator. Advantageously, in addition to detecting the proximity of a nerve to the first dilator, the apparatus permits determination of the direction of the nerve from the first dilator. This facilitates more efficient re-positioning of the apparatus for avoidance of nerves, if a new path is necessary.

What is claimed is: 
     
         1 . An apparatus for dilating bodily tissue and for monitoring neural activity in the distracted bodily tissue, said apparatus comprising:
 a first dilator having a tubular body with a distal end, a proximal end, and at least one electrode mounted about a circumference thereof; and,   a second dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end, and a lumen extending therebetween sized to permit said second dilator to telescopically slide over said first dilator and come into overlapping coaxial alignment with said first dilator, a discrete window being formed through said tubular body in communication with said lumen,   wherein, with said second dilator being in overlapping coaxial alignment with said first dilator, said window being located to come into registration with said at least one electrode such that, upon rotation of said second dilator relative to said first dilator, said window is positionally adjustable about the circumference of said first dilator.   
     
     
         2 . An apparatus as in  claim 1 , wherein said at least one electrode is annular. 
     
     
         3 . An apparatus as in  claim 1 , wherein said at least one electrode includes a plurality of electrodes. 
     
     
         4 . An apparatus as in  claim 3 , wherein said electrodes are evenly spaced about the circumference of said first dilator. 
     
     
         5 . An apparatus as in  claim 1  further comprising a third dilator having a tubular body with a distal end, a proximal end, and a lumen extending therebetween sized to permit said third dilator to telescopically slide over said second dilator and come into overlapping coaxial alignment with said second dilator. 
     
     
         6 . An apparatus as in  claim 5 , wherein, at least one channel extends along an outer surface of said tubular body of said third dilator. 
     
     
         7 . An apparatus as in  claim 6 , wherein said at least one channel extends from said proximal end of said tubular body. 
     
     
         8 . An apparatus for monitoring neural activity in bodily tissue and for dilating the monitored tissue, said apparatus comprising:
 a first dilator having a tubular body with a distal end, a proximal end, and a plurality of electrodes mounted at equal intervals about a circumference thereof; and,   means for separately monitoring electrical activity of each of said electrodes.   
     
     
         9 . An apparatus as in  claim 8  further comprising a second dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end, and a lumen extending therebetween sized to permit said second dilator to telescopically slide over said first dilator and come into overlapping coaxial alignment with said first dilator. 
     
     
         10 . An apparatus as in  claim 9 , wherein said second dilator includes a plurality of windows corresponding to said plurality of electrodes. 
     
     
         11 . A system for monitoring neural activity in bodily tissue and for dilating the monitored tissue, said system comprising:
 a first dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end, and a plurality of axially extending channels formed about a circumference thereof extending from said proximal end towards said distal end; and,   a probe formed to be sequentially introduced in said channels.   
     
     
         12 . A system as in  claim 11 , wherein said tubular body further having at least one transverse channel in communication with a distal terminus of at least one said channel, said transverse channel being transversely disposed relative to said channel in communication therewith. 
     
     
         13 . A system as in  claim 12 , wherein said transverse channel having a radial expanse greater than a radial expanse of said channel and extending a limited extent of said circumference of said tubular body so as to not circumscribe said tubular body. 
     
     
         14 . A system as in  claim 11 , wherein said channels are disposed at four substantially equally spaced locations about the circumference of said tubular body. 
     
     
         15 . A system as in  claim 11 , further comprising a second dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end and a lumen extending therebetween sized to permit said second dilator to telescopically slide over said first dilator, a plurality of channels being formed about a circumference of said tubular body of said second dilator formed each to accommodate said probe. 
     
     
         16 . A method of monitoring neural activity in bodily tissue, comprising the steps of:
 introducing a first dilator into bodily tissue having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end, and at least one electrode mounted adjacent the distal end around a circumference thereof;   introducing a second dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end, and a lumen extending therebetween sized to permit said second dilator to telescopically slide over said first dilator, a discrete window being formed through said tubular body of said second dilator adjacent the distal end thereof in communication with said lumen, said window being placed during introduction of said second dilator in coaxial alignment with said electrode;   electrifying said electrode to cause current to flow through said window;   rotating said second dilator circumferentially about said first dilator; and   monitoring nerve activity radially as said window is rotated about the electrode on said first dilator.   
     
     
         17 . A method as in  claim 16 , wherein prior to introducing said first dilator an initial probe is introduced through said bodily tissue to said target site and nerve activity is monitored during said introduction. 
     
     
         18 . A method as in  claim 17 , wherein said first dilator comprises a lumen extending axially therethrough for receipt therethrough of said initial probe, and with said initial probe being in position in said bodily tissue and serving as a guide wire, said first dilator is telescopically placed over said initial probe with said initial probe extending through said lumen. 
     
     
         19 . A method of monitoring neural activity in bodily tissue, comprising the steps of:
 introducing a first dilator into bodily tissue, said first dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end, and a plurality of axially extending channels formed about a circumference thereof extending from said proximal end towards said distal end, each channel being formed to accommodate said probe, said distal end of said first dilator being placed adjacent a target site;   attaching a probe to a neuromonitoring device capable of electrifying said probe and monitoring nerve proximity;   introducing said probe sequentially into each of said channels with a tip of said probe being placed adjacent and exposed to said target site, electrifying the tip of said probe and monitoring nerve activity at each channel, and removing said probe from each channel thereafter;   providing a second dilator having a tubular body of electrically-insulative material, said tubular body having a distal end, a proximal end and a lumen extending therebetween sized to permit said second dilator to telescopically slide over said first dilator, a plurality of axially extending channels being formed about a circumference of said tubular body of said second dilator extending from said proximal end towards said distal end, each channel being formed each to accommodate said probe;   telescopically sliding said second dilator axially over said first dilator with the distal end of said second dilator being placed adjacent said target site; and   introducing said probe sequentially into each of said channels of said second dilator with a tip of said probe being placed adjacent and exposed to said target site, electrifying the tip of said probe and monitoring nerve activity at each channel of said second dilator, and removing said probe from each channel thereafter.   
     
     
         20 . The method as in  claim 19 , wherein prior to introducing said first dilator an initial probe is introduced through said bodily tissue to said target site and nerve activity is monitored during said introduction. 
     
     
         21 . The method as in  claim 19 , wherein said first dilator comprises a lumen extending axially therethrough for receipt therethrough of said initial probe, and with said initial probe in position and said bodily tissue and serving as a guide wire, said first dilator is telescopically placed over said initial probe with said initial probe extending through said lumen.