Flexible surgical sheath and multi-part insertion cannula

Abstract

A flexible surgical sheath and multi-part insertion cannula for inserting the flexible sheath in a cranial surgical tunnel for gaining access to a ventricle or other surgical target. An obturator or other elongated insertion member drives a sheath assembly into a surgical recess, typically a hole drilled through the skull and brain of the surgical patient. The inserted sheath assembly includes two or more rigid sheath portions disposed around the obturator. The obturator has a tapered or angled tip for guiding the sheath assembly through the surgical tunnel to a target region such as a ventricle or other brain structure for which surgical intervention is sought. Following insertion, the obturator is withdrawn and a flexible sheath inserted in an insertion tunnel defined by the rigid sheath portions.

1 - 14 . (canceled) 
     
     
         15 . A flexible sheath for providing surgical access, comprising:
 a tubular member having a resilient tubular shape for insertion into a surgical tunnel, the surgical tunnel adapted to provide simultaneous access by a plurality of surgical instruments;   the tubular member deformably responsive to the surgical instruments for resiliently expanding in response to periodic biasing force for mitigating prolonged forces disposing the surgical tissue; and   the tubular member returning to an unbiased, unexpanded shape upon relaxation of the surgical instruments.   
     
     
         16 . The flexible sheath of  claim 15 , wherein the tubular member is responsive to a plurality of rigid sheath portions for insertion therebetween, the rigid sheath portions adapted for ordered withdrawal prior to application of the periodic biasing force. 
     
     
         17 . The flexible sheath of  claim 16 , wherein the rigid sheath portions are elongated and tapered for defining a depth and size of the surgical passageway, the depth corresponding to a surgical site and the size tapered from a distal end adjacent the surgical site and a proximate end adapted for insertion of the surgical instruments. 
     
     
         18 . The flexible sheath of  claim 15 , wherein the tubular member is expandable in response to the biasing forces and adapted to return to an unexpanded shape. 
     
     
         19 . The flexible sheath of  claim 16 , wherein the expandable tubular shape has an unexpanded diameter less than an inside diameter of the inserted rigid sheath portions. 
     
     
         20 . The flexible sheath of  claim 19 , wherein each rigid sheath portion has a handle defined by an extension normal to an outer surface of the sheath at a proximate end, the distal end inserted into the surgical passageway. 
     
     
         21 . The flexible sheath of  claim 16 , being constructed as ribbed with alternating folds.