Shunt malfunction and endoscopy
Authors: Iskandar Bermans , Gepp Ricardo de Amoreira 
Published: February 2021

Objective:
Hydrocephalus is the most common neurological disease in pediatric neurosurgery.(1) The CSF shunts remains as the most common treatment choice for nonobstructive hydrocephalus worldwide, but shunt complications still the most common neurosurgical problem, especially in pediatric neurosurgery. Endoscopy and shunts are the way to treat hydrocephalus. Especially third ventriculostomy is the most effective treatment to obstructive hydrocephalus but shunt still the most important way to treat.(2, 3) Shunt malfunction is frequent and after so many years this is very important problem to the patients. Ventricular problem due to obstruction is responsible up to 72% of shunt problems.(4) The Shunt Trial Study showed that the overall shunt survival was 62% at 1 year, 52% at 2 years, 46% at 3 years, 41% at 4 years. The survival curves for the 3 differents valves were similar to those from the original trial and did not show a survival advantage for any particular valve.(5, 6) We still don´t have one perfect solution to hydrocephalus and shunt malfunction.
The major author described his experience in use endoscopy to evaluate and treat shunt malfunction and one new approach and way to evaluate this problem.

Results/Discussion:
The literature review was performed, and we found 84 articles when we used the keywords. Endoscopy has been one important way to treat and solve shunt problems. In obstructive hydrocephalus third ventriculostomy is the best way to treat these patients.(1-3)
The major author first described goals of endoscopy. First goal is safe catheter removal in surgical review, avoiding bleeding when removing catheter addressing all the adhesions on catheter. Second goal is put in optimal position the new catheter with pure endoscopy view or using neuronavigation systems that could help the endoscope system.(7, 8)
Optimal new catheter placement and optimal long-term catheter survival are especially important because most of the problems are due to ventricular problems. These good placements could avoid loculations and ventricular collapse with ependymal problems. Avoid new catheter malpositiitioning, you can use the endoscope to follow the old tract to insert the new catheter in one good position avoiding choroid plexus. Another situation is when you have small ventricles especially in slit ventricle syndrome.

The major author has been studied some causes to ventricular catheter obstruction. He noticed after some surgical reviews some ventricular ependymal inside catheter. Ventricular ependymal protrusions inside the catheter could cause intermittent occlusion.(8) Some endoscope views showed these protrusion and ependymal changes after intermittent increase and decrease of ventricular pressure. These protrusions correspond to catheter holes a secondary to suction. These protrusions could stuck in the holes in chronicle suction.(8) The major author reported one endoscopic evidence of overdrainage-related ventricular tissue protrusions that cause partial or complete obstruction of the ventricular catheter. He did a retrospective review in fifty patients underwent 83 endoscopic shunt revision procedures that revealed in-growth of ventricular wall tissue into the catheter tip orifices (ependymal bands), producing partial, complete, or intermittent shunt obstructions. Endoscopic ventricular explorations revealed ependymal bands at various stages of development, which appear to form secondarily to siphoning.(8)
How to minimize this overshunting? Anti siphon systems could help and decrease proximal shunt malfunction in some complex patients. The other problem is ventricular bleeding. The use of endoscope has been important tool to remove ventricular catheters, when you could see the adhesions.(9)
The use the endoscope could be particularly important to open loculations and cysts avoiding ventricular entrapment. Patients with ventricular cysts could need more than one catheter. The use of endoscopy to fenestrate the cyst could keep the patient with one catheter or without any shunt system.(10, 11)

Conclusion:
Shunt malfunction has a lot of possible causes, but a probably ventricular catheter problem is the most common situation. Choose appropriate endoscope rigid or flexible for each case could help to treat and avoid some of ventricular. Endoscopy could be one important tool to help the surgeon to understand and solve this dangerous situation to the patient. Ventricular wall protrusions are a significant cause of proximal shunt obstruction, and they appear to be caused by siphoning of surrounding tissue into the ventricular catheter orifices.