Hindbrain Herniation and Banana and Lemon Sign After Open Fetal Myelomeningocele Repair – When Do These Signs Disappear and is Shunting Predictable?

Abstract

Purpose The aim was to describe the sonographic follow-up of hindbrain herniation (HH), the banana and lemon sign after fetal myelomeningocele (fMMC) repair, and the time of disappearance of these signs after the intervention, and to investigate any predictive value for the necessity of shunting during the infant’s first year of life. Additionally, the sonographic evolution of the transcerebellar diameter (TCD) before and after fetal intervention was assessed.

Patients and Methods The first 50 patients that underwent fMMC repair at Zurich Center for Fetal Diagnosis and Therapy (www.swissfetus.ch) were included in this study. Sonographic scans performed weekly after fMMC repair focusing on HH and banana and lemon signs were analyzed and compared between the shunted and the non-shunted group. ROC curves were generated for the time intervals of resolution of the signs in order to show their predictive accuracy for the need for shunting until 1 year of age.

Results HH resolved in 48 fetuses (96 %) before delivery. The sonographic disappearance of HH within the first two weeks after fMMC repair was associated with a significantly lower incidence of shunt placement (OR 0.19; 95 % CI 0.4–0.9) during the first year of life (p = 0.03). All fetuses with persistent HH before delivery received a shunt. TCD growth was observed in all fetuses.

Conclusion The reversibility of HH within two weeks after fMMC repair is associated with an 80 % lower incidence of shunt placement during the infant’s first year of life. Moreover, it allows the cerebellum to grow and to normalize its configuration.

Zusammenfassung

Ziel Ziele dieser Studie waren, die sonografische Entwicklung der Kleinhirnherniation (KH) sowie des Bananen- und Zitronenzeichens nach fetalem Myelomeningozelen (fMMC)-Verschluss sowie das Zeitintervall bis zum Verschwinden dieser Zeichen nach der Intervention zu beschreiben und herauszufinden, ob diese Messungen zur Vorhersage der Shunt-Bedürftigkeit im ersten Lebensjahr dieser Kinder verwendet werden können. Zusätzlich wurde der transzerebelläre Durchmesser (TCD) vor und nach der Intervention sonografisch erhoben.

Patienten und Methode Die ersten 50 der am Zürcher Zentrum für Fetale Diagnostik und Therapie (www.swissfetus.ch) operierten Kinder wurden eingeschlossen. Die nach dem fMMC-Verschluss wöchentlich erfassten sonografischen Bilder wurden analysiert und zwischen der geshunteten und nicht geshunteten Gruppe verglichen. Um den Vorhersagewert der Shunt-Bedürftigkeit im ersten Lebensjahr vorherzusagen, wurden ROC-Kurven für die Zeitintervalle bis zum Verschwinden der Zeichen generiert.

Ergebnisse Die KH löste sich bei 48 der Föten (96 %) auf. Die sonografische Reversibilität der KH in den ersten 2 Wochen nach fMMC-Verschluss war mit einer signifikant tieferen Inzidenz der Shunt-Bedürftigkeit im ersten Lebensjahr vergesellschaftet (OR 0,19; 95 %-KI 0,4–0,9; p = 0,03). Alle Föten mit persistierender KH haben einen Shunt bekommen. Ein Wachstum des TCD konnte bei allen Föten beobachtet werden.

Schlussfolgerung Die Reversibilität der KH interhalb der ersten 2 Wochen nach fMMC-Verschluss geht mit einer 80 % niedrigeren Inzidenz der Shunt-Bedürftigkeit im ersten Lebensjahr dieser Kinder einher. Zudem erlaubt sie die Normalisierung des Kleinhirnwachstums und dessen Konfiguration.

Key words

myelomeningozele - fetal surgery - hindbrain herniation - banana sign - lemon sign

Publication History

Received: 23 May 2019

Accepted: 29 January 2020

Article published online:
24 April 2020

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