Fig. 6

Neuroendoscopic video-captured images showing phantom III-VT in 2 different babies (= black sign). (A-H) first baby: A, B Yellowish CSF can be seen. Lower inset comparing the initial syringe containing yellow CSF “left” and final clear result “right” after endoscopic lavage and replacement with CSF substitute. No landmarks at all. Scout around for the dorsum sellae (DS) to imagine the III-VT floor (ǂ) between the DS and aqueduct of Sylvius (AS). Notice the choroid plexus (CP) of the everted III-VT roof. C A view through the AS showing the yellowish discoloration of the CP of the fourth ventricle (4th VT). D Close view to the site of expected ETV stoma: Pituitary fossa (PF), DS, floor (ǂ). E Palpation of the DS with Fogarty catheter (*), perforation with Decq forceps (#: upper inset) and enlarging the stoma with balloon (*: lower inset). F Naked basilar artery (BA) and exposed posterior cerebral artery (PCA) are not enough as the thick/dense Liliequist membrane mesencephalic layer (LM-ML) still preventing adequate CSF communication with SAS/BC (= red sign). G, H) following several attempts to open the LM-ML, the clivus (CL), brainstem (BS) and left abducent nerve (VI) are exposed. However, it was extremely difficult and hazardous. I–N showing another baby with phantom III-VT (= black sign). I Cutting the intraventricular synechiae beside veins (V) with bipolar electro-cautery (*) to face a phantom III-VT floor (ǂ) and scout around to find the DS. J stepwise stoma creation just behind the DS with Decq forceps (DF) which is used to create 2 stomas with closed DF (upper inset) then open it parallel to the clivus (lower inset) and try to put each blade of DF inside each stoma to start dissection. K Thick multilayered LM is seen beyond the phantom III-VT floor and initial exposure of the basilar artery (BA). L BA, superior cerebellar artery (SCA), brainstem (BS), DS and multilayered thin/transparent LM (white arrows) are seen. M removing on layer of LM exposing the left abducent nerve (VI). N lateral view showing the left oculomotor nerve (III) in the angle between the posterior cerebral artery (PCA/¶) and posterior communicating artery (Pcom/‡) and its relation to the created stoma within the thin/transparent LM (white arrow). Upper and lower insets demonstrating different magnifications to catch a panoramic view