PMC4533358_01
HD endoscope with a camera head (A, upper) and ICG endoscope (A, lower). The ICG endoscope is 1 cm longer and 1.8 mm larger in diameter (B). Burr = 10 mm. ICG: indocya-nine green.
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F1
To identify the fine edge of the left ICA and to confirm patency of the cavernous sinus, we injected 5 ml of ICG (25 mg dissolved in 10 ml of sterile water) into a peripheral vein after changing to the ICG endoscope system (Fig. 1A, lower).
Computed tomography (CT) scans (A) and magnetic resonance images (MRIs) before the first operation showing an intra-cavernous sinus dermoid tumor. T1-weighted axial (B) and fat suppression coronal image with Gd-enhancement (C). Intraoperative photograph demonstrating the white sebaceous contents containing hairs (pterional approach) (D). Photomicrograph of a hematoxylin-eosin-stained section (E). T1-weighted coronal image after the first operation showing no residual mass (F). Coronal CT image and T1-weighted coronal image (H) showing the recurrent dermoid cyst 4 years after the first operation.
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A computed tomography (CT) scan acquired at that time revealed a hypodense round mass lesion in the left cavernous sinus (Fig. 2A). The mass lesion was hyperintense on T1- and heterogeneously hyperintense on T2-weighted images; it was not contrast enhanced (Fig. 2B). T1-weighted images was suppressed on fat-suppression MRI images (Fig. 2C). The lesion was resected subtotally via the pterional approach. The white sebaceous cyst content containing hairs was removed (Fig. 2D). As pathological study showed squamous epithelium and hairs the final diagnosis was dermoid cyst (Fig. 2E). Postoperative T1-weighted MRI confirmed resection of the hyperintense mass lesion (Fig. 2F) and his symptoms disappeared soon after the operation. The dermoid cyst was located in the left cavernous sinus; the left carotid siphon was slightly extended by the tumor which partially faced the sphenoid sinus covered by the dura and by bone at the skull base (Fig. 2G-H).
Intraoperative photographs showing the endoscopic view of the sphenoid sinus before (A) and after partial removal of bone of the sellar floor (B). Intraoperative photographs just after cutting the dura. Outflow of the dermoid cyst content (C). T1-weighted coronal image after the second operation by ETSS revealing no residual tumor mass (D). Fluorescence signals were detected by the ICG endoscope. The signal intensity changed with the passage of time (original: E-H, traced: I-L). The ICA, traced by a dotted line (B, I-L), and then the cavernous sinus (arrowheads) were detected (F-G, J-L). The signal from the mucosa in the clival region was upregulated (G, K) and finally the pituitary gland was identified (H, L). Arrowheads: cavernous sinus, asterisks: residual septum in the sphenoid sinus, broken line: pituitary gland, Cli: clivus, DC: dermoid cyst, dotted line: internal carotid artery, ETSS: endoscopic transnasal transsphenoidal surgery, IC: internal carotid artery bone-covered (ICc) and bone-uncovered (ICu), ICA: internal carotid artery, ICG: indocyanine green, OP: optic prominence, PG: pituitary gland.
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The dura mater around the sellar floor was exposed, and the cavernous sinus predominantly on the left side was detected with the assistance of navigation (Fig. 3A-B). The fluorescence signals from flowing ICG in the left ICA were seen to pass through the dura and the bone that partially covered the ICA (Fig. 3B, E, I). A few seconds later, the patent cavernous sinus was identified (Fig. 3F, J, and G, K). The mucosa covering the clivus showed fluorescent signals (Fig. 3G, K). The normal pituitary gland became gradually visible more than 30 seconds after ICA detection (Fig. 3H, L). The low fluorescent signal from the dermoid cyst in the cavernous sinus was slightly increased through the dura (Fig. 3H, L). We next cut the dura, taking care to protect the ICA and the patent cavernous sinus, and evacuated the cystic fluid whose consistency was like that of motor oil (Fig. 3C).
Changes in the fluorescent signals. The time of first detection of ICG in the ICA was designated 0 second. CS: cavernous sinus, ICA: internal carotid artery, ICG: indocyanine green, Mucosa: mucosa in the clival region.
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Figure 4 shows the changes in the fluorescent signals.