Towards a ventriculo-venous shunt that works
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1
University Hospital Ghent, Neurosurgery, Belgium
The clinical problem
At present, hydrocephalus is being treated by ventriculo-peritoneal or ventriculo-atrial shunts. These shunts possess an essential disadvantage: they do not establish physiological intracranial pressures. In a sitting or standing position of the patient, the cerebrospinal fluid column within the catheter – through gravity – exerts suction (siphoning), leading to shunt-related intracranial hypotension.This siphon effect is only imperfectly counteracted by the resistance of the valve.
Ventriculo-venous shunts
In healthy individuals, the cerebrospinal fluid (CSF) is resorbed to the superior sagittal sinus, an intradural venous canal. Shunting to this natural resorption site reduces the risk of shuntfailure in several ways. First,overdrainage is prevented by preservation of the natural, self-regulating anti-siphon effect of the internal jugular vein. This vein constantly adapts its diameter and thus the resistance against drainage of blood and cerebrospinal fluid out of the skull in function of the patient´s position. Secondly, the shunt system is shorter, less complex and confined to the skull, whichminimizes the risk of mechanical failure and infection. Ventriculo-sinus shunts have been used in both pediatric and adult patients (more than 150 patients in total) to treat high- and normal-pressure hydrocephalus. No complications and shunt responses similar to those of conventional shuntswere reported. One author reported an excellent long-term efficacy. However, in a small prospective trial at our hospital 80% of the sinus shunts occluded within 4 months after implantation, although we respected all technical recommendations of the literature. Furthermore it was striking to us that no new information was released concerning this technology despite the very promising results reported in the literature.
Material and methods
The authors developed a dural venous sinus access device (DVSAD) that has significant advantages compared to the currently used silicone catheter. First, the tip is secured in the center of the superior sagittal sinus and secondly the endovascular volume is minimized. In the center of the sinus the risk of clotformation is minimal because blood velocity is maximal, there is no contact with the endothelial vessel wall, and the concentration of platelets and clotting factors is lowest. The DVSAD is designed in such a way that the tip is always in the center of the sinus. Stabilization with an epidural baseplate and intravascular barb minimizes the risk of dislocation. A foreign volume in a blood vessel disturbs the blood flow. It creates zones of low, non laminar flow in which the risk of clot formation is high. The DVSAD has a volume of only 40mm³, which is significant less than the conventional shunt (600mm³).
Results and Conclusion
Prototypes were designed with computer-aided design software and manufactured by injection molding. The prototypes were then evaluated in a cadaver study and in an in-vivo animal trial (goat model).The prototypes were correctly implanted in all animals. None of the animals developed venous sinus thrombosis, air embolism, or excessive intra-operative sinus bleeding. The application of a small prospective clinical trial on ten adult patients was recently approved by the local Ethics Committee of Ghent University Hospital.
Summary
We present a new prototype of the ventriculo-venous shunt that minimizes the risk of shuntobstruction by clot formation in the venous vessel. If this prototype proves to be efficacious in humans, ventriculo-venous shunting will finally be possible. This might be a revelation in the treatment of hydrocephalus. Ventriculo-venous shunts, in contrast to the currently used ventriculoperitoneal shunts restore the physiological intracranial pressure. By consequence the risk of shunt failure, which is as high as 50% over two years in ventriculo-peritoneal shunts will be drastically reduced.
Sammentvatting in het Nederlands
We stellen een nieuw prototype hersenvocht-shunt tussen hersenkamer en sinusader voor, dat het risico op shuntverstopping door bloedklonters moet minimaliseren. Indien dit prototype bij mensen goed zou blijken te werken, wordt het eindelijk mogelijk ventriculo-veneuze shunts aan te leggen. Dit zou een omwenteling kunnen betekenen in de behandeling van hydrocefalie. Ventriculo-veneuze shunts herstellen namelijk de fysiologische druk binnen de schedel. Bijgevolg kan ook het risico op shuntfalen drastisch verminderd worden, dat bij ventriculo-peritoneale shunts tot 50% over verloop van twee jaar kan bedragen.
Résumé en français :
Nous proposons un nouveau prototype de dérivation du liquide cérébrospinal entre ventricule et sinus veineux afin de réduire au minimum l’obturation de la dérivation par des caillots de sang. Si ce prototype devait également fonctionner correctement chez l’homme, il serait enfin possible de réaliser des dérivations ventriculo-veineuses, ce qui serait un progrès révolutionnaire pour le traitement de l’hydrocéphalie. De fait, les dérivations ventriculo-veineuses rétablissent la pression physiologique dans le crâne. Par conséquent, il est possible de réduire radicalement le risque d’un shunt ventriculo-péritonéal défectueux, lequel risque peut s’élever à 50% sur une période de deux ans.
Keywords:
Hydrocephalus;,
Ventriculo-venous shunt,
overdrainage,
Prototype,
Animal Experimentation
Conference:
6th Belgian Brain Congress, MONS, Belgium, 8 Oct - 8 Oct, 2016.
Presentation Type:
Poster Presentation
Topic:
Brain and brain diseases: between heredity and environment
Citation:
Vandersteene
J,
Baert
E,
Dewaele
F and
Van Roost
D
(2016). Towards a ventriculo-venous shunt that works.
Conference Abstract:
6th Belgian Brain Congress.
doi: 10.3389/conf.fnagi.2016.03.00060
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Received:
11 Jul 2016;
Published Online:
11 Jul 2016.
*
Correspondence:
Dr. Jelle Vandersteene, University Hospital Ghent, Neurosurgery, Ghent, Oost-Vlaanderen, 9000, Belgium, jellevdsteene@gmail.com