Stepped cannula

Abstract

Described herein are cannulas having a stepped exterior. Also described are methods of making and using these cannulas, for example to deliver one or more materials to the central nervous system of an animal.

1 . A stepped cannula having an exterior diameter, a distal end, a proximal end and a lumen extending between the proximal and distal ends, the stepped cannula comprising
 two or more co-axially disposed segments, each segment having an exterior diameter that defines the exterior diameter of the cannula,   wherein the exterior diameter of the segments is different.   
     
     
         2 . The stepped cannula of  claim 1  comprising two, three, four, five or six co-axially disposed segments. 
     
     
         3 . The stepped cannula of  claim 1 , wherein the exterior diameter of the segments decreases from the proximal end to the distal end of the cannula. 
     
     
         4 . The stepped cannula of  claim 1 , wherein the interior diameter of the cannula is constant. 
     
     
         5 . The stepped cannula of  claim 1 , further comprising one or more tubular components extending through the lumen of the cannula. 
     
     
         6 . The stepped cannula of  claim 5 , wherein at least one tubular component comprises fused silica tubing. 
     
     
         7 . The stepped cannula of  claim 6 , further comprising FEP tubing disposed around the fused silica tubing. 
     
     
         8 . The stepped cannula of any  claim 1 , wherein one or more segments comprise stainless steel. 
     
     
         9 . The stepped cannula of  claim 8 , wherein the lumen of one or more of the stainless steel segments is coated with one or more polymers. 
     
     
         10 . The stepped cannula of  claim 1 , comprising five stainless steel segments. 
     
     
         11 . A cannula assembly comprising:
 a cannula according to  claim 1 ; and   a reservoir comprising the one or more materials to be delivered through the cannula, the reservoir operably connected to the lumen of the cannula.   
     
     
         12 . The cannula assembly of  claim 11 , wherein the reservoir comprises a syringe. 
     
     
         13 . The cannula assembly of  claim 11 , further comprising a pump operably linked to the syringe. 
     
     
         14 . The cannula assembly of  claim 13 , wherein the pump is programmable. 
     
     
         15 . The cannula assembly of  claim 11 , wherein the reservoir is operably linked to the tubing extending through the lumen of the cannula. 
     
     
         16 . A method of delivering one or more materials to a target area in a subject, the method comprising the steps of
 positioning a cannula according to  claim 1  at the target area of the subject; and   delivering the one or more materials to the target area through the cannula.   
     
     
         17 . The method of  claim 16 , wherein the target area is in the central nervous system. 
     
     
         18 . The method of  claim 17 , wherein the target area is in the brain. 
     
     
         19 . The method of  claim 16 , wherein the material is selected from the group consisting of biologically active agents, dyes, tracers, markers, contrast agents or combinations thereof. 
     
     
         20 . The method of  claim 19 , wherein the biologically active agent is an AAV vector. 
     
     
         21 . A stepped cannula having an exterior diameter, a distal end, a proximal end and a lumen extending between the proximal and distal ends, the stepped cannula comprising
 two or more co-axially disposed segments, each segment having an exterior diameter that defines the exterior diameter of the cannula, wherein the exterior diameter of the segments is different; and   one or more tubular components extending through the lumen of the cannula.   
     
     
         22 . A stepped cannula having an exterior diameter, a distal end, a proximal end and a lumen extending between the proximal and distal ends, the stepped cannula comprising
 two or more co-axially disposed segments, each segment having an exterior diameter that defines the exterior diameter of the cannula, wherein the exterior diameter of the segments is different; and   one or more tubular components extending through the lumen of the cannula, wherein at least one tubular component comprises fused silica.   
     
     
         23 . The stepped cannula of  claim 1 , further comprising:
 means, positioned in said lumen, for reducing loss of material delivered to a target area through said cannula.   
     
     
         24 . The stepped cannula of  claim 23 , wherein said means comprises fused silica.