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Joyce Koueik, Brandon G. Rocque, Jordan Henry, Taryn Bragg, Jennifer Paul and Bermans J. Iskandar

Continuous irrigation is an important adjunct for successful intraventricular endoscopy, particularly for complex cases. It allows better visualization by washing out blood and debris, improves navigation by expanding the ventricles, and assists with tissue dissection. A method of irrigation delivery using a centrifugal pump designed originally for cardiac surgery is presented.

The BioMedicus centrifugal pump has the desirable ability to deliver a continuous laminar flow of fluid that excludes air from the system. A series of modifications to the pump tubing was performed to adapt it to neuroendoscopy. Equipment testing determined flow and pressure responses at various settings and simulated clinical conditions. The pump was then studied clinically in 11 endoscopy cases and eventually used in 310 surgical cases.

Modifications of the pump tubing allowed for integration with different endoscopy systems. Constant flow rates were achieved with and without surgical instruments through the working ports. Optimal flow rates ranged between 30 and 100 ml/min depending on endoscope size. Intraoperative use was well tolerated with no permanent morbidity and showed consistent flow rates, minimal air accumulation, and seamless irrigation bag replacement during prolonged surgery. Although the pump is equipped with an internal safety mechanism to protect against pressure buildup when outflow obstructions occur, equipment testing revealed that flow cessation is not instantaneous enough to protect against sudden intracranial pressure elevation.

A commonly available cardiac pump system was modified to provide continuous irrigation for intraventricular endoscopy. The system alleviates the problems of inconsistent flow rates, air in the irrigation lines, and delays in changing irrigation bags, thereby optimizing patient safety and surgical efficiency. Safe use of the pump requires good ventricular outflow and, clearly, sound surgical judgment.

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Tarek Y. El Ahmadieh, Cody B. Wolfe, Joyce Koueik, Bradley E. Weprin, Bermans J. Iskandar and Angela V. Price

Neuroendoscopy has demonstrated safety and efficacy in the treatment of a host of pediatric neurosurgical pathologies. With the increase in its applicability, several associated complications have been described in the literature. A common practice in pediatric neurosurgery is the use of Gelfoam sponge pledget in the burr hole, followed by bone fragments and dust (obtained from the created burr hole), to cover the dural defect. This technique is used to enhance burr hole sealing and potentially prevent CSF leakage from the surgical site. Reports on intracranial bone dust migration associated with this technique are scarce. The authors report 2 cases of intracranial migration of bone fragments after an endoscopic third ventriculostomy and an endoscopic colloid cyst resection. The bone fragment migration was thought to be caused by negative pressure from a lumbar puncture in one case and external trauma to the head in the other. As endoscopy becomes more widely used, it is important to be aware of this potential complication that may in some cases require an intervention. A review of the cases reported in the literature is provided and a technique is suggested to help prevent this complication.

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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.

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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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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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Joyce Koueik, Carolina Sandoval-Garcia, John R. W. Kestle, Brandon G. Rocque, David M. Frim, Gerald A. Grant, Robert F. Keating, Carrie R. Muh, W. Jerry Oakes, Ian F. Pollack, Nathan R. Selden, R. Shane Tubbs, Gerald F. Tuite, Benjamin Warf, Victoria Rajamanickam, Aimee Teo Broman, Victor Haughton, Susan Rebsamen, Timothy M. George and Bermans J. Iskandar

OBJECTIVE

Despite significant advances in diagnostic and surgical techniques, the surgical management of Chiari malformation type I (CM-I) with associated syringomyelia remains controversial, and the type of surgery performed is surgeon dependent. This study’s goal was to determine the feasibility of a prospective, multicenter, cohort study for CM-I/syringomyelia patients and to provide pilot data that compare posterior fossa decompression and duraplasty (PFDD) with and without tonsillar reduction.

METHODS

Participating centers prospectively enrolled children suffering from both CM-I and syringomyelia who were scheduled to undergo surgical decompression. Clinical data were entered into a database preoperatively and at 1–2 weeks, 3–6 months, and 1 year postoperatively. MR images were evaluated by 3 independent, blinded teams of neurosurgeons and neuroradiologists. The primary endpoint was improvement or resolution of the syrinx.

RESULTS

Eight clinical sites were chosen based on the results of a published questionnaire intended to remove geographic and surgeon bias. Data from 68 patients were analyzed after exclusions, and complete clinical and imaging records were obtained for 55 and 58 individuals, respectively. There was strong agreement among the 3 radiology teams, and there was no difference in patient demographics among sites, surgeons, or surgery types. Tonsillar reduction was not associated with > 50% syrinx improvement (RR = 1.22, p = 0.39) or any syrinx improvement (RR = 1.00, p = 0.99). There were no surgical complications.

CONCLUSIONS

This study demonstrated the feasibility of a prospective, multicenter surgical trial in CM-I/syringomyelia and provides pilot data indicating no discernible difference in 1-year outcomes between PFDD with and without tonsillar reduction, with power calculations for larger future studies. In addition, the study revealed important technical factors to consider when setting up future trials. The long-term sequelae of tonsillar reduction have not been addressed and would be an important consideration in future investigations.