Systems and methods for tissue ablation

Abstract

Systems and methods for tissue ablation. Systems include needles with deployable filaments capable of producing asymmetrical offset lesions at target volumes, which may include a target nerve. Ablation of at least a portion of the target nerve may inhibit the ability of the nerve to transmit signals, such as pain signals, to the central nervous system. The offset lesion may facilitate procedures by directing energy towards the target nerve and away from collateral structures. Example anatomical structures include lumbar, thoracic, and cervical medial branch nerves and rami and the sacroiliac joint.

1 . A needle comprising:
 an elongate member having a distal end;   a tip coupled to the distal end of the elongate member, the tip comprising a bevel portion comprising a point on a side of the elongate member; and   a plurality of filaments movable between a first position at least partially in the elongate member and a second position at least partially out and to the side of the elongate member, the plurality of filaments and the tip configured to transmit radio frequency energy from a probe to operate as a monopolar electrode.   
     
     
         2 . The needle of  claim 1 , wherein the elongate member has a proximal end and wherein the needle further comprises a filament deployment mechanism coupled to the proximal end of the elongate member, the filament deployment mechanism comprising:
 an advancing hub including a stem coupled to the plurality of filaments;   a spin collar including a helical track, the stem of the advancing hub at least partially inside the spin collar; and   a main hub comprising a stem comprising a helical thread configured to cooperate with the helical track, the stem of the main hub at least partially inside the spin collar, the stem of the advancing hub at least partially inside the main hub,   wherein, upon rotation of the spin collar, the filaments are configured to move between the first position and the second position.   
     
     
         3 . The needle of  claim 2 , wherein a single wire comprises the plurality of filaments and wherein a proximal end of the wire is coupled to the stem of the advancing hub. 
     
     
         4 . The needle of  claim 2 , wherein at least one of the helical track and the helical thread includes a plurality of detents configured to indicate partial deployment or retraction of the plurality of filaments. 
     
     
         5 . The needle of  claim 4 , wherein the first position is a fully retracted position and the second position is a fully deployed position, and wherein the detents are configured to provide an audible or tactile feedback to a user when the filaments are at a third position between the first position and the second position, a fourth position between the third position and the second position, and a fifth position between the fourth position and the second position. 
     
     
         6 . The needle of  claim 5 , wherein the plurality of filaments are proximal to the point in the third position, the plurality of filaments are substantially longitudinally aligned with the point in the fourth position, and the plurality of filaments are distal to the point in the fifth position. 
     
     
         7 . The needle of  claim 1 , wherein the bevel portion has a bevel angle between about 20° and about 30°. 
     
     
         8 . The needle of  claim 1 , wherein each of the plurality of filaments has a distal end including a bevel facing away from the tip. 
     
     
         9 . The needle of  claim 8 , wherein the bevels of the plurality of filaments are at an angle between about 25° and about 35°. 
     
     
         10 . The needle of  claim 1 , wherein a single wire comprises the plurality of filaments. 
     
     
         11 . The needle of  claim 1 , further comprising an insulating coating at least partially covering the point. 
     
     
         12 . The needle of  claim 1 , wherein the tip comprises a stem at least partially in the elongate member, the stem including a first filament lumen and a second filament lumen. 
     
     
         13 . The needle of  claim 12 , wherein stem includes a third lumen and wherein the bevel portion comprises a fluid port in communication with the third lumen. 
     
     
         14 . The needle of  claim 1 , wherein the elongate member has a proximal end, and wherein the needle further comprises a rotational deployment mechanism coupled to the proximal end of the elongate member, the deployment mechanism comprising indicia of fractional deployment of the plurality of filaments relative to the tip. 
     
     
         15 . The needle of  claim 15 , wherein the indicia include at least one of audible and tactile detents. 
     
     
         16 . A needle comprising:
 an elongate member having a distal end;   a tip comprising
 a first body portion including a tapered portion and a point, the tapered portion including a plurality of filament ports; and 
 a second body portion coupled to the distal end of the elongate member, the second body portion at an angle with respect to the first body portion; and 
   a plurality of filaments movable between a first position at least partially in at least one of the tip and the elongate member and a second position at least partially out of the filament ports, the plurality of filaments and the tip configured to transmit radio frequency energy from a probe to operate as a monopolar electrode.   
     
     
         17 . The needle of  claim 16 , wherein the angle is between about 20° and about 30°. 
     
     
         18 . The needle of  claim 16 , wherein each of the plurality of filaments has a distal end including a pencil-point tip. 
     
     
         19 . The needle of  claim 16 , wherein the tapered portion includes a pencil-point tip. 
     
     
         20 . A method of heating a vertebral disc, the method comprising:
 positioning a distal end of a needle in a posterior annulus;   deploying a filament out of the needle;   traversing the posterior annulus from lateral to medial;   applying radio frequency energy to the tip and to the filament; and   ablating pain fibers in the posterior annulus.