Jeremy S. Wetzel, David P. Heaner, Brandon C. Gabel, R. Shane Tubbs and Joshua J. Chern
The majority of children with myelomeningocele undergo implantation of CSF shunts. The efficacy of adding surveillance imaging to clinical evaluation during routine follow-up as a means to minimize the hazard associated with future shunt failure has not been thoroughly studied.
A total of 300 spina bifida clinic visits during the calendar years between 2012 and 2016 were selected for this study (defined as the index clinic visit). Each index visit was preceded by a 6-month period during which no shunt evaluation of any kind was performed. At the index clinic visit, all patients were evaluated by a neurosurgeon. Seventy-four patients underwent previously scheduled surveillance CT or shunt series scans in addition to clinical evaluation (surveillance imaging group), and 226 patients did not undergo surveillance imaging (clinical evaluation group). Subsequent unexpected events, defined as emergency department visits, caregiver-requested clinic visits, and shunt revision surgeries were reviewed. The timing and likelihood of an unexpected event in each of the 2 groups were compared using Cox proportional hazard survival analysis. The rate of shunt revision surgery in the follow-up period as well as the associated outcomes and rate of complications were analyzed.
The clinical characteristics of the 2 groups were similar. In the clinical evaluation group, 4 of 226 (1.8%) patients underwent shunt revision based on clinical findings during the index visit, compared to 8 of 74 (10.8%) patients in the surveillance imaging group who underwent shunt revision based on clinical and imaging findings at that visit (p < 0.05). In the subsequent follow-up period, there were 74 unexpected events resulting in 10 shunt revisions in the clinical evaluation group, for an event rate of 33% and operation rate of 13.5%. In the surveillance imaging group there were 23 unexpected events resulting in 2 shunt revisions, for an event rate of 34.8% and an operation rate of 8.7%; neither difference was statistically significant. The complication rate for shunt revision surgery was also not different between the groups.
Obtaining predecided, routine surveillance imaging in children with myelomeningocele and shunted hydrocephalus resulted in more shunt revisions in asymptomatic patients. For patients who had negative results on surveillance imaging, the rate of shunt revision in the follow-up period was not significantly decreased compared to patients who underwent clinical examination only at the index visit.
Jeremy S. Wetzel, Alex D. Waldman, Pavlos Texakalidis, Bryan Buster, Sheila R. Eshraghi, Jennifer Wheelus, Andrew Reisner and Joshua J. Chern
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.
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.
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).
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.