Commentary: Converting Pediatric Patients and Young Adults From a Shunt to a Third Ventriculostomy: A Multicenter Evaluation

Given the clinical burden of shunt failure and infection over a lifetime, the potential to convert patients to shunt independence is highly valuable. One such strategy for patients when in shunt failure or undergoing shunt revision is to consider performing an endoscopic third ventriculostomy (ETV). In the published article by Hersh et al³ and colleagues, the authors evaluated the success of converting from shunt to ETV in patients with existing ventricular shunts over a 10-yr period. In their cohort of 80 patients, 64% of patients achieved shunt-independence at a median follow-up of 2.0 yr. Four patients required a repeat ETV procedure. The authors identified that age was the only factor significantly predictive of ETV failure with older patients having a more favorable diagnosis.

The published study provides valuable evidence that patients requiring a shunt revision may be excellent candidates for ETV. Rather than primarily focus on the etiology of the hydrocephalus, the authors recognize that careful radiographic review by magnetic resonance or computed tomography to identify the area of cerebrospinal fluid (CSF) obstruction serves as a valuable piece of information in assessing candidacy for ETV. The most common site of blockage involved the cerebral aqueduct and fourth ventricle. This focus on identifying the site of CSF flow obstruction is applicable even in patients with prior intraventricular hemorrhage or tumor resection. In these cases, debris or scarring impacting CSF dynamics may mature with time, which may impact surgical candidacy.

This study complements published studies, such as prospective studies by Kulkarni et al 2016, which included a subset of patients that had previous shunt.¹ The ETV Success Score (ETVSS) is a definition of success that was estimating the chance of success of the procedure at 6 mo. The ETVSS calculates a score based on 3 factors: patient age, cause of hydrocephalus, and the presence or absence of a previous shunt. While highly valuable in the pediatric patient population, the findings of this study also have substantial implications for adult neurosurgeons evaluating patients in shunt failure or with an infection. Generally, after obtaining necessary imaging and performing a shunt tap, patients are taken to the operating room for shunt interrogation and revision. This presents an opportunity for neurosurgeons to consider if ETV would be helpful to relieve CSF flow obstruction and achieve shunt independence. Although a proportion of patients will certainly fail ETV, the authors recognize that placement of an Ommaya reservoir following ETV as may serve as safety measure in the event of ultimate ETV failure.

While the data was provided at a minimum follow up of 6 mo, it will be of significant interest to determine the durability of benefit for patients in shunt failure treated with an ETV. In addition, while a large cohort of patients analyzed retrospectively across 3 centers, it is unclear to what degree ETV in patients with an existing shunt could be successful across a broader range of etiologies and whether these results are generalizable across other centers. ETV has known complications including CSF leak, hemorrhage, and infection.² Thus, the neurosurgical community would benefit from a multicenter prospective randomized control trial investigating ETV in patients with an existing shunt.

Disclosures

The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.