Maximising coverage of brain structures using controlled reflux, convection-enhanced delivery and the recessed step catheter

Owen Lewis, Max Woolley, David E Johnson, Julia Fletcher, Johnathan Fenech, Mariusz W Pietrzyk, Neil U Barua, Alison S Bienemann, Will Singleton, Sam L Evans, Steven S Gill

Research output: Contribution to journalArticle (Academic Journal)peer-review

24 Citations (Scopus)
321 Downloads (Pure)



The design and use of convection-enhanced delivery catheters remains an active field as clinical trials have highlighted suboptimal distribution as a contributory factor to the failure of those studies. Recent studies indicate limitations and challenges in achieving target coverage using conventional point source delivery.


The recessed step catheter(RSC), developed by this group, does not function as a point source delivery device, but instead uses 'controlled reflux' of the infusate to a flow inhibiting recess feature. Here we investigate a range of clinically useful step lengths in agarose gel and investigate proof-of-principle in vivo(n = 5). Infusion morphology was characterised in terms of length, width and distribution volume over a range of flow rates.


For a fixed infusion volume, increases in catheter step length strongly correlated with increases in the length and volume of distribution (r>0.90, p < 0.001) whilst there were small reductions in the width of distribution (r<-0.62, p < 0.001). Step lengths below 6 mm produced spherical distributions while steps above 12 mm produced elongated distributions. Increasing peak flow rates resulted in significant reductions in distribution volume at each step length, and an increased risk of reflux beyond the step. Modifications to the infusion morphology using changes in step length were confirmed in vivo.


The combination of the recessed step and the ability to adjust the step length with this catheter design make it highly suitable for tailoring the distribution volume of the infusate to meet specific morphological target volumes in the brain.

Original languageEnglish
Pages (from-to)337-345
Number of pages9
JournalJournal of Neuroscience Methods
Early online date1 Sept 2018
Publication statusPublished - 1 Oct 2018


  • Controlled reflux
  • Parkinson’s disease
  • Recessed-step-catheter
  • Convection-Enhanced Delivery


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