Elsevier

World Neurosurgery

Volume 109, January 2018, Pages 162-164
World Neurosurgery

Case Report
Agenesis of Anterior Falx Cerebri in Patient with Planned Interhemispheric Approach to Third Ventricle Mass

https://doi.org/10.1016/j.wneu.2017.09.166Get rights and content

Background

Complete or partial agenesis of the falx cerebri may occur in pediatric patients with developmental anomalies. However, isolated agenesis of the falx in a developmentally normal adult is exceptionally rare. We describe the first reported case of a patient with a third ventricular mass associated with partial agenesis of the anterior falx cerebri, a circumstance that influenced surgical access to a third ventricular epidermoid cyst.

Case Description

A 60-year-old developmentally normal woman presented with progressively worsening aphasia and altered mental status. Brain magnetic resonance imaging showed obstructive hydrocephalus from a third ventricular mass. An anterior interhemispheric transcallosal approach was planned to remove the tumor. However, upon dural opening there was no evidence of a falx cerebri, an anomaly visible but not reported on the prior imaging studies. An interhemispheric fissure was present, but the medial frontal lobes were densely adherent, with multiple traversing veins within the superficial arachnoid of the fissure. Therefore, a left frontal transcortical approach was performed for microsurgical resection of the tumor. Histopathologic analysis identified the lesion to be an epidermoid cyst.

Conclusions

Partial agenesis of the falx cerebri is exceedingly rare in a developmentally normal adult, particularly in the presence of an anatomically normal superior sagittal sinus. If present, however, it is important to note this association preoperatively because partial agenesis of the falx cerebri precludes an interhemispheric transcallosal approach to the lateral and third ventricles.

Introduction

Complete or partial agenesis of the falx cerebri rarely occurs in pediatric patients with developmental anomalies. However, isolated agenesis of the falx cerebri in a developmentally normal adult without concomitant agenesis of the superior sagittal sinus or corpus callosum is exceptionally uncommon. We report an adult patient with agenesis of the anterior part of the falx cerebri with obstructive hydrocephalus from a third ventricular epidermoid cyst and discuss the neurosurgical implications.

Section snippets

Case Report

A 60-year-old developmentally normal female with a 3-year history of a conservatively managed third ventricular mass (Figure 1) presented with headache, altered mental status, and aphasia. Brain computed tomography and magnetic resonance imaging demonstrated interval enlargement of the mass, which originated at and extended superiorly from the inferior recesses of the third ventricle and partially through the left foramen of Monro (Figure 2). The lateral ventricles were dilated, and there was

Discussion

The falx cerebri represents the interhemispheric dural reflection separating the left and right cerebral hemispheres. Agenesis of the falx cerebri is extremely rare and most commonly associated with the alobar and semilobar forms of the holoprosencephaly spectrum as a secondary consequence of hemispheric fusion and other associated midline abnormalities.1, 2 Absence, fenestration, or hypoplasia of the dural reflections are also uncommon but well-documented sequelae of the Chiari II malformation3

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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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