A New Optimal Marker to Evaluate the Effectiveness of Endoscopic Third Ventriculostomy During Operation: “Folding Sign”

Abstract

Endoscopic third ventriculostomy (ETV) remains the mainstay of treatment for noncommunicating hydrocephalus these days. However, there has been no adequate clue for the intraoperative assessment of ETV efficacy until now. This time, we propose a newly defined finding, "folding sign," which is visible and enables us to confirm penetration of both the third ventricle floor and the Liliequist membrane (LM) during operation. In this report, we describe consecutive ETV cases and discuss the mechanism of folding sign and its clinical meanings. A folding sign is a formation of a sequence of folds at the tectal region, which is easily detectable. A total of 30 patients with newly diagnosed hydrocephalus between October 2014 and February 2018 at Tokyo Women's Medical University were enrolled in our case series (age range, 3 months to 74 years). The difference between proportions was analyzed by the χ2 method. In all, 12 patients (40%) showed a folding sign: congenital hydrocephalus including aqueductal stenosis (AS) and isolated fourth ventricle in 4 patients, and brain tumor-associated noncommunicating hydrocephalus in 8 patients. Statistical analysis showed that the emergence of a folding sign was related to successful ETV, indicating it as an optimal intraoperative sign to assess the effectiveness of this procedure (P= 0.0298). The folding sign is a newly defined sign to predict the success of ETV during operation. This optimal finding appears only when the LM is sufficiently opened; therefore, it could be a good candidate for an intraoperative assessment tool.