Abstract
IntroductionFourth ventricle outlet obstruction (FVOO) is a rare cause of obstructive hydrocephalus. We describe a case of idiopathic FVOO that was successfully treated with endoscopic third ventriculostomy (ETV).Case reportA 3-year old boy without any remarkable medical history presented with a headache and vomiting. Computed tomography (CT) images, which had incidentally been taken 2 years previously due to a minor head injury, showed no abnormality. Magnetic resonance imaging on admission showed tetra-ventricular hydrocephalus associated with the dilatation of the fourth ventricle outlets, without any obstructive lesions. However, CT ventriculography, involving contrast medium injection through a ventricular catheter, suggested mechanical obstruction of the cerebrospinal fluid (CSF) at the fourth ventricle outlets. Thus, the patient was diagnosed with FVOO and ETV was performed; the hydrocephalus was subsequently resolved. Although hydrocephalus recurred 1 year postoperatively, re-ETV for the highly stenosed fenestration successfully resolved this condition.ConclusionsETV should be considered for FVOO treatment, particularly in idiopathic cases without CSF malabsorption.
Highlights
Fourth ventricle outlet obstruction (FVOO) is a rare cause of obstructive hydrocephalus
endoscopic third ventriculostomy (ETV) should be considered for FVOO treatment, in idiopathic cases without cerebrospinal fluid (CSF) malabsorption
We describe the case of childhood idiopathic FVOO without any remarkable medical history that was successfully treated by endoscopic third ventriculostomy (ETV), and provide a review of the relevant literature
Summary
Fourth ventricle outlet obstruction (FVOO) is an uncommon clinical condition that causes obstructive hydrocephalus. Magnetic resonance imaging (MRI) showed enlargement of all ventricular systems associated with the dilatation of the foramina of Magendie and Luschka, with no obstructive organic lesions (such as brain tumors) on contrast enhanced MRI (Fig. 1b–f ). On serial CT images, contrast medium was accumulated in the foramina of Magendie and Luschka 1 h after injection, with limited diffusion to the adjacent cisterns at 3 h after injection. These findings suggested a mechanical obstruction at the outlets of the fourth ventricle. The endoscope was inserted into the fourth ventricle through the dilated cerebral aqueduct and encountered the suspected cause of obstructive hydrocephalus—a thickened, arachnoid, membranous structure that enveloped the foramina of Magendie and Luschka (Fig. 3). The patient has remained in good condition without recurrence of hydrocephalus, as identified by MRI, since undergoing the second ETV for 20 months
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