Surgical methodology and protocols for preventing implanted cerebral catheters from becoming obstructed during and after neurosurgery

Abstract

BACKGROUND\nConvection Enhanced Delivery (CED) into targeted brain areas has been tested in animal models and clinical trials for the treatment of various neurological diseases.\n\n\nNEW METHOD\nWe used a series of techniques, to in effect, maintain positive pressure inside the catheter relative to the outside, that included a hollow stylet, a high volume bolus of solution to clear the line, a low andslow continuous flow rate during implantation, and heat sealing the catheter at the time of implantation.\n\n\nRESULTS\n120 catheters implanted into brain parenchyma of 89 adult female rhesus monkeys across four sets of experiments. After experiencing a high delivery failure rate - non patent catheters - (19%) because of tissue entrapment and debris and/or blood clots in the catheter tip, we developed modifications, including increasing the bolus infusion volume from 10 to 20\u2009µl such that by the third experiment, the failure rate was 8% (1 of 12 implants). Increasing the bolus volume to 100\u2009µl and maintaining positive pressure in the catheter during preparation and implantation yielded a failure rate of 0% (0/12 implants) by the fourth experiment.\n\n\nCOMPARISON WITH EXISTING METHODS\nWe provide a retrospective analysis to reveal how several different manipulations affect catheter patency and how post-op MRI examination is essential for assessing catheter patency in situ.\n\n\nCONCLUSIONS\nThe results of the present study identified that the main cause of the catheter blockages were clots that rendered the catheter non-patent. We resolved this by modifying the surgical procedures that prevented these clots from forming.