PMC7398264_01
Preoperative MR image. a and b The T2-weighted axial image: multiple arachnoid cysts. c and d Preoperative Cine phase-contrast MR image: Arrow directs that the aqueduct of sylvius and the exit of fourth ventricle are blocked. e The T2-weighted coronal MR image: Arrow shows that the left anterior cranial fossa is likely communicated with the left ethmoid sinus. f A coronal high-resolution bone window noncontrast CT image: Arrow indicates that left ethmoid is discontinuous
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Fig1
The prepontine cistern, interpeduncular cistern, suprasellar cistern, quadrigeminal cistern, cavum septum pellucidum and third and lateral ventricles were markedly dilated (Fig. 1a and b). Cine phase-contrast MRI showed the aqueduct of sylvius was blocked by cyst originated from quadrigeminal cistern (Fig. 1c and d). A high-resolution bone window noncontrast CT image indicates that left ethmoid is discontinuous (Fig. 1f).
Intraoperative neuroendoscopic views. a Two cysts (c1 and c2) bulging into the right lateral ventricle. b Along the choroid plexus we find no trace of the foramen of Monro. c: Fenestration of the apical membrane in front of the midline (f1). d and e Anatomical landmarks seen after the endoscope is advanced into the first cyst (c1). f Fenestration of the apical membrane behind the midline (f2). g and h Two fenestrations of the basal cyst membrane behind the midline (f3 and f4). p = plexus choroideus; 1 = septal vein; 2 = thalamostriate vein; 3 = choroidal vein; A1 = the horizontal segment of the anterior cerebral artery; A2 = the ascending part of the anterior cerebral artery; AC = anterior communicating artery;  Indicates the optic chiasma
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Fig2
In the right lateral ventricle, we found the walls of two cysts (Fig. 2a). Then, the cyst wall was resected as much as possible by using scissors to make a large fenestration (f1) in its apical membrane (Fig. 2b and c). Behind the fenestration, some anatomical landmarks such as chiasmatic cisterns, anterior cerebral artery, optic chiasma were clearly visualized (Fig. 2d and e). Then, we make a fenestration in avascular portions of the apical cyst membrane behind the midline by using scissors (Fig. 2f). Finally, we make two fenestrations in the basal cyst membrane, which would allow communication between the cyst and quadrigeminal cistern (Fig. 2g and h).
Images obtained a week after the operation. a T2-weighted axial MR image. b and c Cine phase-contrast MR image. b Arrow indicates that satisfactory CSF flow through aqueduct of Sylvius is detected.  Indicates the fenestrations of the apical membrane (f1 and f2). c  Indicates two fenestrations of the basal cyst membrane behind the midline (f3 and f4)
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Fig3
MRI and lumbar puncture were done after a week and 6 months respectively, and the shape of fourth ventricle was back to normal and satisfactory CSF flow through aqueduct of Sylvius was detected. MRI displayed that the volume of lateral ventricles and the cavity of septum pellucidum decreased well (Fig. 3).
Images obtained 9 months after the operation. a T2-weighted coronal MR image. Arrow shows that the left anterior cranial fossa is communicated with the left ethmoid sinus. b and c The coronal and axial high-resolution bone window noncontrast CT images: Arrow indicates that there is a poor continuity of bone in the left ethmoid
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Fig4
MRI showed that the left anterior cranial fossa was communicated with the left ethmoid sinus and the computed tomography (CT) indicated that there is a poor continuity of bone in the left ethmoid (Fig. 4).