Devices and methods for radiofrequency neurotomy

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.

What is claimed is: 
     
         1 . 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.   
     
     
         2 . The needle of  claim 1 , wherein the angle is between about 20° and about 30°. 
     
     
         3 . The needle of  claim 1 , wherein each of the plurality of filaments has a distal end including a pencil-point tip. 
     
     
         4 . The needle of  claim 1 , wherein the tapered portion includes a pencil-point tip. 
     
     
         5 . 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.