Devices and methods for accessing the epidural space

Abstract

An apparatus for accessing the epidural space in a mammal has a cutting sheath with a distal end adapted to transition from a closed cutting configuration to an open configuration. A tissue engagement device is in a hollow portion of the sheath. The tissue engagement device has a blunt distal end and an engagement feature. A method of accessing an epidural space includes the step of forming an opening to a position at or near the ligamentum flavum using the cutting sheath. Another step of the method is positioning a tissue engagement device within the hollow portion of the cutting sheath. Another step of the method is transitioning the cutting sheath from the closed cutting configuration to the open configuration. Another step of the method is manipulating the tissue engagement device to controllably advance the tissue engagement device at least partially through the ligamentum flavum.

1 - 15 . (canceled) 
     
     
         16 . A method of accessing an epidural space in a mammal, comprising:
 forming an opening in the mammal at or near the ligamentum flavum using a cutting sheath having an open proximal end, a distal end adapted to transition from a closed cutting configuration to an open configuration, and a hollow portion within the sheath extending from the open proximal end;   positioning within the hollow portion of the cutting sheath a tissue engagement device having an elongate body with a proximal end, a blunt distal end, and an engagement feature on an exterior surface of the elongate body;   transitioning the distal end of the cutting sheath from the closed cutting configuration to the open configuration; and   using the engagement feature to controllably advance the blunt distal end of the elongate body at least partially through the ligamentum flavum.   
     
     
         17 . The method according to  claim 16 , the act of transitioning comprising moving the tissue engagement device relative to the cutting sheath. 
     
     
         18 . The method according to  claim 17 , wherein the act of moving the tissue engagement device relative to the cutting sheath comprises pulling the cutting sheath proximally relative to the tissue engagement device. 
     
     
         19 . The method according to  claim 17 , wherein the act of moving the tissue engagement device relative to the cutting sheath comprises rotating the tissue engagement device within the hollow portion of the cutting sheath. 
     
     
         20 . The method according to  claim 16 , the act of transitioning comprising moving a portion of the distal end of the cutting sheath about a hinge. 
     
     
         21 . The method according to  claim 16 , wherein one or both of the act of transitioning and the act of using are performed by rotating the tissue engagement device. 
     
     
         22 . The method according to  claim 16 , wherein one or both of the act of transitioning and the act of using are performed by longitudinal movement between the tissue engagement device and the cutting sheath. 
     
     
         23 . The method according to  claim 16 , further comprising ceasing the advancement of the blunt distal end when a pressure drop within the tissue engagement device is detected. 
     
     
         24 . The method according to  claim 16 , wherein at least one section on the distal end of the cutting sheath moves in a predetermined manner. 
     
     
         25 . The method according to  claim 16 , further comprising:
 advancing a substance, therapeutic instrument or diagnostic instrument through a conduit within the tissue engagement device.   
     
     
         26 . (canceled) 
     
     
         27 . The method according to  claim 16 , wherein the act of transitioning exposes the blunt distal end of the tissue engagement device to the ligamentum flavum. 
     
     
         28 . The method according to  claim 16 , wherein the act of transitioning comprises removing a stylet from within the hollow portion. 
     
     
         29 . (canceled) 
     
     
         30 . A method of accessing an epidural space in a mammal, comprising:
 percutaneously accessing a ligamentum flavum in the mammal;   placing a device into the ligamentum flavum, wherein the device has a portion that includes an opening;   using the ligamentum flavum to controllably advance the device relative to the ligamentum flavum until the portion of the device that has the opening exits from the ligamentum flavum.   
     
     
         31 . The method of  claim 30 , wherein the act of accessing the ligamentum flavum comprises inserting a tubular member through a skin of the mammal until a distal end of the tubular member reaches the ligamentum flavum. 
     
     
         32 . The method of  claim 31 , wherein when the tubular member is being inserted through the skin, tissue is prevented from entering into a lumen in the tubular member through the distal end of the tubular member. 
     
     
         33 . The method of  claim 32 , wherein after the distal end of the tubular member has reached the ligamentum flavum, the device is advanced distally so that at least a part of the device is out of the distal end of the tubular member. 
     
     
         34 . The method of  claim 30 , further comprising:
 after the portion of device with the opening exits from the ligamentum flavum, advancing a tube inside the device relative to the device until a distal end of the tube is outside the opening of the device; and   delivering fluid into the mammal using the tube.   
     
     
         35 . The method of  claim 30 , wherein the device has a channel that is in fluid communication with the opening, and wherein the method further comprises applying fluid pressure to fluid in the channel while the device is being rotated relative to the ligamentum flavum. 
     
     
         36 . The method of  claim 35 , further comprising sensing a drop in the fluid pressure. 
     
     
         37 . The method of  claim 30 , wherein the ligamentum flavum is used to prevent the device from being pushed distally while allowing the device to turn relative to the ligamentum flavum. 
     
     
         38 . An apparatus for accessing the epidural space in a mammal, comprising:
 a sheath having a distal end, a proximal end, and a lumen extending between the distal end and the proximal end;   a tissue engagement device disposed within the lumen of the sheath, the tissue engagement device having an elongate body with a proximal end and a blunt distal end;   an engagement feature at the elongate body;   an aperture at the elongate body; and   a conduit within the elongate body in communication with the aperture.   
     
     
         39 . The apparatus of  claim 38 , wherein the engagement feature comprises a screw thread. 
     
     
         40 . The apparatus of  claim 39 , wherein the aperture is at the screw thread. 
     
     
         41 . The apparatus of  claim 38 , wherein the distal end of the sheath has an open configuration in a first mode of operation, and a closed configuration in a second mode of operation. 
     
     
         42 . The apparatus of  claim 38 , wherein the aperture is at a side of the elongate body proximal to the blunt distal end. 
     
     
         43 . The apparatus of  claim 38 , wherein the aperture is at the blunt distal end. 
     
     
         44 . The apparatus of  claim 38 , wherein the engagement feature is configured to engage with a ligamentum flavum, and to translate relative to the ligamentum flavum in a controllable manner. 
     
     
         45 . The apparatus of  claim 38 , wherein the aperture faces towards a direction that forms an angle with a longitudinal axis of the elongate body. 
     
     
         46 . A method of accessing an epidural space in a mammal, comprising:
 percutaneously accessing a ligamentum flavum in the mammal;   placing a device into the ligamentum flavum, wherein the device has a portion that includes an opening;   controllably moving the portion of the device from a first position inside the ligamentum flavum to a second position inside the ligamentum, the second position being closer to a spinal cord than the first position.   
     
     
         47 . The method of  claim 46 , wherein the act of controllably moving the portion of the device comprises using the ligamentum flavum. 
     
     
         48 . The method of  claim 46 , wherein the act of controllably moving the portion of the device comprises turning the device relative to the ligamentum flavum. 
     
     
         49 . The method of  claim 46 , further comprising controllably moving the portion of the device from the second position inside the ligamentum flavum to a third position outside the ligamentum flavum.