title: Strategies for the delivery of multiple collinear infusion clouds in convection-enhanced delivery in the treatment of Parkinson's disease.
abstract: BACKGROUND
  Delivery of multiple collinear payloads utilizing convection-enhanced delivery (CED) has historically been performed by retraction of a needle or catheter from the most distal delivery site. Few studies have addressed end-infusion morphology and associated payload reflux in stacked and collinear infusions, and studies comparing the advancement with the retraction mode are lacking.
  
  
  OBJECTIVE
  To compare advancement versus retraction mode infusion results.
  
  
  METHODS
  Infusion cloud pairs were created with the advancement and retraction technique in agarose gel using both open end-port SmartFlow (SF) and valve tip (VT) catheter infusion systems. Backflow, radius of infusion, and morphology were assessed.
  
  
  RESULTS
  Infusions with the SF catheter, in contrast to the VT catheter, exhibited significantly more backflow in retraction mode at the shallow infusion site. Infusion morphology differed with the second infusion after retraction: the infusate at the proximal site first filling the channel left by the retraction and then being convected into gel in a pronouncedly non-spherical shape during the second infusion.
  
  
  CONCLUSIONS
  Significant differences in cloud morphology were noted with respect to external catheter geometry with retraction versus penetration between infusions in an agarose gel model of the brain. Further study is warranted to determine optimal protocols for human clinical trials employing CED with multiple collinear payloads.
authors: Department of Neurological Surgery, University of Wisconsin, Madison, Wisconsin, USA. sillay@neurosurgery.wisc.edu
authors: Karl
authors: K
authors: Sillay
authors: Angelica
authors: A
authors: Hinchman
authors: Lauren
authors: L
authors: Kumbier
authors: Dominic
authors: D
authors: Schomberg
authors: Chris
authors: C
authors: Ross
authors: Ken
authors: K
authors: Kubota
authors: Martin
authors: M
authors: Brady
authors: Ethan
authors: E
authors: Brodsky
authors: Gurwattan
authors: G
authors: Miranpuri
authors: Raghu
authors: R
authors: Raghavan
mesh_terms: D001921:Brain; D057785:Catheters; D018481:Convection; D016503:Drug Delivery Systems / Q000379:methods*; D005782:Gels; D006801:Humans; D010300:Parkinson Disease / Q000188:drug therapy*
chemical_list: D005782:Gels