New Research Clarifies Rates of Shunt Infection, Malfunctions, and Long-Term Outcomes in Cases of Myelomeningocele

August 16, 2021

A new study on shunt infection and malfunctions in cases of myelomeningocele with symptomatic hydrocephalus provides new findings on long-term outcomes. Stephanie Greene, MD, director of vascular neurosurgery at the Brain Care Institute at UPMC Children’s Hospital of Pittsburgh, was the senior author of the study1 published in May in the Journal of Neurosurgery Pediatrics. The study was selected as the Editor's Choice for this edition of the journal for its potential impact on clinical practice with shunt use in myelomeningocele. This study is the second of Dr. Greene's investigations published in the past year to have been selected as an Editor's Choice feature in the journal.

Study Overview

Hydrocephalus occurs in a high percentage of cases of myelomeningocele, necessitating correspondingly high placement rates of ventriculoperitoneal shunt. However, long-term outcomes data in these cases related to shunt infection rates, malfunctions, and revision procedures has been lacking. Shunt infection rates in patients with myelomeningocele are significantly higher than in other indications or causes of symptomatic hydrocephalus. Infections and shunt malfunctions lead to revision procedures and other patient morbidities.

This single-institution study retrospectively examined 170 cases of myelomeningocele closure performed at UPMC Children's Hospital of Pittsburgh over 22 years, from 1995 to 2017. The team’s analysis examined rates of shunt insertion, revision rates, and shunt infection rates

It is important to note that in this study, Dr. Greene and colleagues’ analysis accounted for and compared outcomes in patient cohorts after 2011 when the hospital instituted the Hydrocephalus Clinical Research Network (HCRN) protocol for shunt cases as a means to avoiding or reducing rates of shunt infection. This protocol was responsible for significant changes in managing patients post-implementation.

Key Findings

In the 170 cases of myelomeningocele closure at UPMC Children’s examined during the study period, 137 or 87% required a ventriculoperitoneal shunt for symptomatic hydrocephalus. Furthermore, the rate of shunt insertion patients who required at least one revision procedure was 21.1% per person-year. This translates to a median revision rate of 0.14 per year, and a mean number of revisions per patient of 2.28 over the entire follow-up period. These rates are comparable to other findings in the literature.

It should be emphasized that while the overall percentage of revision procedures appears high for the study (72%), the follow-up period for this study is more than 20 years, an extraordinarily long period for such a study, making comparisons with studies of much shorter duration that exhibit lower rates incomparable. It should also be noted that shunt placements, in general, decreased over time.

Concerning infection rates, Dr. Greene's study found that patients with shunts experienced an infection rate of 2.1% per person-year across the study. Of the 137 cases of shunt placements analyzed in the study, 15.3% of patients had at least 1 infection, but this was over a mean follow-up period of 10.8 years. More than half (52%) of the infections occurred during the first year of life, and patients experienced a mean of 3.4 surgeries (both initial shunt insertion or revisions) before having their initial infection.

Of note, the rate of subsequent shunt infections was found to be higher in cases where shunt externalization, in which the distal shunt is removed from the peritoneum and attached to a drainage collection bag, leaving the remainder of the shunt in place, was used during an active infection compared to cases where there was immediate removal of the shunt and temporary transition to external drainage.

When comparing cohorts of patients from 1995 to 2011, and after 2011 when the HCRN protocol was implemented at UPMC Children's, Dr. Greene's study team found no significant differences in outcomes between the two groups in either the rate of shunt infections or the number of revisions required and in several other metrics. 

“As the HCRN protocol was implemented in order to standardize shunt surgery across institutions in the United States, theoretically reducing complications associated with the procedure, it was a surprising finding that our research uncovered no statistically significant differences in outcomes after we began using the HCRN measures," says Dr. Greene.

Clinical Implications

The most important finding from the new study is that neurosurgeons should be cognizant of the high rates of shunt malfunction and infections in patients with myelomeningocele.

Furthermore, the data from Dr. Greene’s analysis show that in cases of shunt infections, shunt externalization is likely not the optimal approach to adopt to clear the infection. 

Neurosurgeons should first consider removing the shunt and transitioning to temporary external drainage while the infection is treated and cleared before replacing the ventriculoperitoneal shunt.

Full details of the study can be found at the reference below.

Reference

1. White MD, McDowell MM, Agarwal N, Greene S. Shunt Infection and Malfunction in Patients With Myelomeningocele. J Neurosurg Pediatr. 2021; 27: 518-524.

More About Dr. Greene

Stephanie Greene, MD, associate professor of neurological surgery, is the director of vascular neurosurgery and director of perinatal neurosurgery in the Brain Care Institute at UPMC Children's Hospital of Pittsburgh. Dr. Greene earned her medical degree from Albany Medical College in New York, followed by residency at the Harvard Medical School/Children's Hospital of Boston/Brigham & Women's Hospital program, and a pediatric neurological surgery fellowship at Seattle Children's Hospital through the University of Washington School of Medicine. Dr. Greene's clinical and research interests are focused on vascular neurosurgery with an emphasis on arteriovenous malformations, fetal neurosurgery, myelomeningocele, and MoyaMoya syndrome. Dr. Greene joined the Brain Care Institute at UPMC Children's in 2009.