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Mark R. Kraemer, Carolina Sandoval-Garcia, Taryn Bragg and Bermans J. Iskandar

OBJECTIVE

The authors conducted a survey to evaluate differences in the understanding and management of shunt-dependent hydrocephalus among members of the American Society of Pediatric Neurosurgeons (ASPN).

METHODS

Surveys were sent to all 204 active ASPN members in September 2014. One hundred thirty responses were received, representing a 64% response rate. Respondents were asked 13 multiple-choice and free-response questions regarding 4 fundamental problems encountered in shunted-hydrocephalus management: shunt malfunction, chronic cerebrospinal fluid (CSF) overdrainage, chronic headaches, and slit ventricle syndrome (SVS).

RESULTS

Respondents agreed that shunt malfunction occurs most often as the result of ventricular catheter obstruction. Despite contrary evidence in the literature, most respondents (66%) also believed that choroid plexus is the tissue most often found in obstructed proximal catheters. However, free-text responses revealed that the respondents’ understanding of the underlying pathophysiology of shunt obstruction was highly variable and included growth, migration, or adherence of choroid plexus, CSF debris, catheter position, inflammatory processes, and CSF overdrainage. Most respondents considered chronic CSF overdrainage to be a rare complication of shunting in their practice and reported wide variation in treatment protocols. Moreover, despite a lack of evidence in the literature, most respondents attributed chronic headaches in shunt patients to medical reasons (for example, migraines, tension). Accordingly, most respondents managed headaches with reassurance and/or referral to pain clinics. Lastly, there were variable opinions on the etiology of slit ventricle syndrome (SVS), which included early shunting, chronic overdrainage, and/or loss of brain compliance. Beyond shunt revision, respondents reported divergent SVS treatment preferences.

CONCLUSIONS

The survey shows that there is wide variability in the understanding and management of shunt-dependent hydrocephalus and its complications. Such discrepancies appear to be derived partly from inconsistent familiarity with existing literature but especially from a paucity of high-quality publications.

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Joyce Koueik, Mark R. Kraemer, David Hsu, Elias Rizk, Ryan Zea, Clayton Haldeman and Bermans J. Iskandar

OBJECTIVE

Recent evidence points to gravity-dependent chronic shunt overdrainage as a significant, if not leading, cause of proximal shunt failure. Yet, shunt overdrainage or siphoning persists despite innovations in valve technology. The authors examined the effectiveness of adding resistance to flow in shunt systems via antisiphon devices (ASDs) in preventing proximal shunt obstruction.

METHODS

A retrospective observational cohort study was completed on patients who had an ASD (or additional valve) added to their shunt system between 2004 and 2016. Detailed clinical, radiographic, and surgical findings were examined. Shunt failure rates were compared before and after ASD addition.

RESULTS

Seventy-eight patients with shunted hydrocephalus were treated with placement of an ASD several centimeters distal to the primary valve. The records of 12 of these patients were analyzed separately due to a complex shunt revision history (i.e., > 10 lifetime shunt revisions). The authors found that adding an ASD decreased the 1-year ventricular catheter obstruction rates in the “simple” and “complex” groups by 67.3% and 75.8%, respectively, and the 5-year rates by 43.3% and 65.6%, respectively. The main long-term ASD complication was ASD removal for presumed valve pressure intolerance in 5 patients.

CONCLUSIONS

Using an ASD may result in significant reductions in ventricular catheter shunt obstruction rates. If confirmed with prospective studies, this observation would lend further evidence that chronic shunt overdrainage is a central cause of shunt malfunction, and provide pilot data to establish clinical and laboratory studies that assess optimal ASD type, number, and position, and eventually develop shunt valve systems that are altogether resistant to siphoning.

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Mark R. Kraemer, Joyce Koueik, Susan Rebsamen, David A. Hsu, M. Shahriar Salamat, Susan Luo, Sara Saleh, Taryn M. Bragg and Bermans J. Iskandar

OBJECTIVE

Ventricular shunts have an unacceptably high failure rate, which approaches 50% of patients at 2 years. Most shunt failures are related to ventricular catheter obstruction. The literature suggests that obstructions are caused by in-growth of choroid plexus and/or reactive cellular aggregation. The authors report endoscopic evidence of overdrainage-related ventricular tissue protrusions (“ependymal bands”) that cause partial or complete obstruction of the ventricular catheter.

METHODS

A retrospective review was completed on patients undergoing shunt revision surgery between 2008 and 2015, identifying all cases in which the senior author reported endoscopic evidence of ependymal tissue in-growth into ventricular catheters. Detailed clinical, radiological, and surgical findings are described.

RESULTS

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. Ependymal bands are associated with small ventricles when the shunt is functional, but may dilate at the time of obstruction.

CONCLUSIONS

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.