Case Series on Removal of Subdural to Peritoneal Shunt After Resolution of Subdural Collection in the First 2 Years of Life.

BACKGROUND: Subdural to peritoneal shunt (SPS) placement is an established treatment option for chronic subdural hematoma (SDH) in the pediatric population. Practice patterns vary between institutions, with some advocating shunt removal while others leave the SPS in place after SDH resolution. There remain a paucity of data to document the safety and outcomes after removal of SPS. OBJECTIVE: To support the safety and efficacy of SPS placement and subsequent removal for chronic SDH in children younger than 2 years. METHODS: A total of 26 patients younger than 2 years underwent SPS removal procedures over a 5-year period from 2015 to 2019 at a single institution. Patient characteristics, hospital course, and outcomes were prospectively recorded in the hospital electronic medical record. Attention was given to change in head circumference, size of subdural collection, need for reoperation, or complications because of shunt removal. RESULTS: Patients who underwent SPS placement presented with macrocephaly, signs and symptoms of increased intracranial pressure, and radiographical evidence of subdural collections. The most common etiology of chronic SDH was nonaccidental head trauma (18 of 26 patients). SDS was kept in place for an average of 10 months. Resolution of SDH was demonstrated on imaging for all 26 patients. One patient did require reinsertion of SPS 2 weeks after SPS removal. CONCLUSION: Removal of SPS remains controversial, and careful consideration of patient, family, and provider preferences and potential risks associated with SPS removal must be taken into consideration.

Unexpected Decrease in Shunt Surgeries Performed during the Shelter-in-Place Period of the COVID-19 Pandemic.

BACKGROUND: It is expected that the incidence of cerebrospinal fluid (CSF) shunt malfunctions would remain unchanged during the shelter-in-place period related to the COVID-19 pandemic. OBJECTIVE: To examine the number of shunt surgeries performed in a single institution during this time interval in comparison to equivalent periods in past years. METHODS: The numbers of elective and emergent/urgent shunt surgeries performed at a single institution were queried for a 28-d period starting on the third Monday of March, between years 2015 and 2020. These were further stratified by how they presented as well as the type of surgery performed. RESULTS: During the 28-d period of interest, in the years between 2015 and 2020, there was a steady increase in the number of shunt surgeries performed, with a maximum of 64 shunt surgeries performed in 2019. Of these, approximately 50% presented in urgent fashion in any given year. In the 4-wk period starting March 16, 2020, a total of 32 shunt surgeries were performed, with 15 of those cases presenting from the outpatient setting in emergent/urgent fashion. For the surgeries performed, there was a statistically significant decrease in the number of revision shunt surgeries performed. CONCLUSION: During the 2020 COVID-19 pandemic, there was an unexpected decrease in the number of shunt surgeries performed, and particularly in the number of revision surgeries performed. This suggests that an environmental factor related to the pandemic is altering the presentation rate of shunt malfunctions.

Survival and failure trends of cerebrospinal fluid shunts with distal slit valves: comparative study and literature review.

OBJECTIVE: The malfunction rates of and trends in various cerebrospinal fluid (CSF) shunt designs have been widely studied, but one area that has received little attention is the comparison of the peritoneal distal slit valve (DSV) shunt to other conventional valve (CV) type shunts. The literature that does exist comes from older case series that provide only indirect comparisons, and the conclusions are mixed. Here, the authors provide a direct comparison of the overall survival and failure trends of DSV shunts to those of other valve type shunts. METHODS: Three hundred seventy-two new CSF shunts were placed in pediatric patients at the authors' institution between January 2011 and December 2015. Only ventriculoperitoneal (VP) shunts were eligible for study inclusion. Ventriculoatrial, lumboperitoneal, cystoperitoneal, subdural-peritoneal, and spinal shunts were all excluded. Rates and patterns of shunt malfunction were compared, and survival curves were generated. Patterns of failure were categorized as proximal failure, distal failure, simultaneous proximal and distal (proximal+distal) failure, removal for infection, externalization for abdominal pseudocyst, and addition of a ventricular catheter for loculated hydrocephalus. RESULTS: A total of 232 VP shunts were included in the final analysis, 115 DSV shunts and 117 CV shunts. There was no difference in the overall failure rate or time to failure between the two groups, and the follow-up period was statistically similar between the groups. The DSV group had a failure rate of 54% and a mean time to failure of 17.8 months. The CV group had a failure rate of 50% (p = 0.50) and a mean time to failure of 18.5 months (p = 0.56). The overall shunt survival curves for these two groups were similar; however, the location of failure was significantly different between the two groups. Shunts with DSVs had proportionately more distal failures than the CV group (34% vs 14%, respectively, p = 0.009). DSV shunts were also found to have proximal+distal catheter occlusions more frequently than CV shunts (23% vs 5%, respectively, p = 0.005). CV shunts were found to have significantly more proximal failures than the DSV shunts (53% vs 27%, p = 0.028). However, the only failure type that carried a statistically significant adjusted hazard ratio in a multivariate analysis was proximal+distal catheter obstruction (CV vs DSV shunt: HR 0.21, 95% CI 0.05-0.81). CONCLUSIONS: There appears to be a difference in the location of catheter obstruction leading to the malfunction of shunts with DSVs compared to shunts with CVs; however, overall shunt survival is similar between the two. These failure types are also affected by other factors such etiology of hydrocephalus and endoscope use. The implications of these findings are unclear, and this topic warrants further investigation.

The Preventable Shunt Revision Rate: A Multicenter Evaluation.

BACKGROUND: The Preventable Shunt Revision Rate (PSRR) was recently introduced as a novel quality metric. OBJECTIVE: To evaluate the PSRR across multiple centers and determine associated variables. METHODS: Nine participating centers in North America provided at least 2 years of consecutive shunt operations. Index surgery was defined as new shunt implantation, or revision of an existing shunt. For any index surgery that resulted in a reoperation within 90-days, index surgery information (demographic, clinical, and procedural) was collected and a decision made whether the failure was potentially preventable. The 90-day shunt failure rate and PSRR were calculated per institution and combined. Bivariate analyses were performed to evaluate individual effects of each independent variable on preventable shunt failure followed by a final multivariable model using a backward model selection approach. RESULTS: A total of 5092 shunt operations were performed; 861 failed within 90 days of index operation, resulting in a 16.9% combined 90-day shunt failure rate and 17.6% median failure rate (range, 8.7%-26.9%). Of the failures, 307 were potentially preventable (overall and median 90-day PSRR, 35.7% and 33.9%, respectively; range, 16.1%-55.4%). The most common etiologies of avoidable failure were infection (n = 134, 44%) and proximal catheter malposition (n = 83, 27%). Independent predictors of preventable failure (P < .05) were lack of endoscopy (odds ratio [OR] = 2.26), recent shunt infection (OR = 3.65), shunt type (OR = 2.06) and center. CONCLUSION: PSRR is variable across institutions, but can be 50% or higher. While the PSRR may never reach zero, this study demonstrates that overall about a third of early failures are potentially preventable.

Movable shark scales act as a passive dynamic micro-roughness to control flow separation.

Shark scales on fast-swimming sharks have been shown to be movable to angles in excess of 50°, and we hypothesize that this characteristic gives this shark skin a preferred flow direction. During the onset of separation, flow reversal is initiated close to the surface. However, the movable scales would be actuated by the reversed flow thereby causing a greater resistance to any further flow reversal and this mechanism would disrupt the process leading to eventual flow separation. Here we report for the first time experimental evidence of the separation control capability of real shark skin through water tunnel testing. Using skin samples from a shortfin mako Isurus oxyrinchus, we tested a pectoral fin and flank skin attached to a NACA 4412 hydrofoil and separation control was observed in the presence of movable shark scales under certain conditions in both cases. We hypothesize that the scales provide a passive, flow-actuated mechanism acting as a dynamic micro-roughness to control flow separation.

Low Reynolds number Couette flow facility for drag measurements.

For this study a new low Reynolds number Couette facility was constructed to investigate surface drag. In this facility, mineral oil was used as the working fluid to increase the shear stress across the surface of the experimental models. A mounted conveyor inside a tank creates a flow above which an experimental model of a flat plate was suspended. The experimental plate was attached to linear bearings on a slide system that connects to a force gauge used to measure the drag. Within the gap between the model and moving belt a Couette flow with a linear velocity profile was created. Digital particle image velocimetry was used to confirm the velocity profile. The drag measurements agreed within 5% of the theoretically predicted Couette flow value.