Shunt infusion studies: impact on patient outcome, including health economics

Abstract

Objectives The diagnosis of shunt malfunction is often not straightforward. We have explored, in symptomatic shunted patients with hydrocephalus or pseudotumour cerebri syndrome (PTCS), the accuracy of CSF infusion tests in differentiating a functioning shunt from one with possible problems, and the health economic consequences. Methods Participants: hydrocephalus/PTCS patients with infusion tests performed from January 2013 until December 2015. We followed patients up after 6 and 12 months from the test to determine whether they had improved, had persisting symptoms or had required urgent revision. We calculated the total cost savings of revision versus infusion tests and standard protocol of revision and ICP monitoring versus infusion tests. Results Three hundred sixty-five shunt infusion tests had been performed where a shunt prechamber/reservoir was present. For hydrocephalus patients, more than half of the tests (~55%, 155 out of 280) showed no shunt malfunction versus 125 with possible malfunction (ages 4 months to 90 years old). For PTCS patients aged 10 to 77 years old, 47 had possible problems and 38 no indication for shunt malfunction. Overall, > 290 unnecessary revisions were avoided over 3 years' time. Two hundred fiftyeight (> 85%) of those non-surgically managed, remained well, did not deteriorate and did not require surgery. No infections were associated with infusion studies. For Cambridge, the overall savings from avoiding revisions was £945,415 annually. Conclusions Our results provide evidence of the importance of shunt testing in vivo to confirm shunt malfunction. Avoiding unnecessary shunt revisions carries a strong health benefit for patients that also translates to a significant financial benefit for the National Health Service and potentially for other healthcare systems worldwide.

Shunt Testing In Vivo: Illustration of Partially Obstructed Ventricular Catheter by In-Growing Choroid Plexus

“…Appropriate management will then depend on the specifics of each case but may include a change in the shunt setting, implantation of an anti-siphon device or treatment of symptoms that are due to another condition. As well as avoiding the risks associated with revision, the average financial gain by unnecessary revisions in our hospital is around one million pounds per year [4]. Infusion tests are safe.…”

“…Finally, shunt testing in vivo can also prevent unnecessary revisions, if the shunt is found to work well during infusion test. Our recent study suggests that in approximately 50% of the tests in patients with a shunt in situ, the shunt system is patent [4]. Appropriate management will then depend on the specifics of each case but may include a change in the shunt setting, implantation of an anti-siphon device or treatment of symptoms that are due to another condition.…”

“…Infusion tests to assess shunt function allow quick, objective assessment of shunt function with forced accelerated flow of fluid through the shunt. Two 25 G needles are inserted transcutaneously into the shunt pre-chamber using sterile preparation and careful skin cleaning [4]. Through one needle Hartmann's fluid is infused and pressure recording is performed through the second needle.…”

Phase‐Contrast MRI Detection of Ventricular Shunt CSF Flow: Proof of Principle

“…The reliable verification of proper shunt functioning is currently only possible with the use of invasive methods, which primarily consist of radionuclide studies or infusion tests using shunt puncture and surgical revision. [22][23][24] A majority of revision surgeries are able to confirm a malfunction of the shunt system with suspension of the CSF flow. Nonetheless, shunt systems that do work properly are frequently assessed by surgery, 20 and regular flow rates in properly working shunt systems have been shown to range between 3 and 30 mL/hour.…”

“…In patients with low tolerance limits for ICP, even a reduced flow rate due to partial shunt obstruction can lead to neurological deterioration. The reliable verification of proper shunt functioning is currently only possible with the use of invasive methods, which primarily consist of radionuclide studies or infusion tests using shunt puncture and surgical revision 22‐24 . A majority of revision surgeries are able to confirm a malfunction of the shunt system with suspension of the CSF flow.…”