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OPERATIVE NUANCES: STEP BY STEP (VIDEO SECTION)
Year : 2023 | Volume
: 71
| Issue : 5 | Page : 893-897
The 10 Ds of Expanded Endonasal Endoscopy for a Giant Tuberculum Sella Meningioma
Sivashanmugam Dhandapani1, Sushant Sahoo1, Rijuneeta Gupta2
1 Department of Neurosurgery, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
2 Department of ENT, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
Correspondence Address:
Sivashanmugam Dhandapani
Department of Neurosurgery, PGIMER, Chandigarh
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/0028-3886.388064
How to cite this article:Key Message: The 10 D technique, as outlined here, is highly effective in dealing with complex skull base meningiomas during endonasal endoscopy.
Objective
We have discussed the principles of endonasal endoscopic surgery for a giant tuberculum sella meningioma in steps of 10 D's.
Procedure
The patient was supine, head fixed on a four-pin head holder, in mild extension, tilted to the left and rotated to the right side, and registered to navigation based on CTA (computed tomography angiography) and contrast MRI (magnetic resonance imaging). The 10 D's of surgery include delineation of the vascularized flap, drilling of the skull base, durotomy, devascularization, decompression, detachment, dissection, delivery of tumor, disengaging tumor from the optic canal, and design of skull base reconstruction. After harvesting the vascularized nasoseptal flap on the right side, a wide sphenoidotomy and posterior ethmoidectomy were carried out. Under adequate binostril exposure, the skull base under the tumor was drilled out under navigation guidance, and the dura opened. Incremental devascularization and internal decompression were initiated along with the detachment of the tumor from the surrounding dura. Circumferential extra-arachnoidal bimanual dissection was performed with micro-rolling maneuvers. The tumor was then delivered progressively. The bilateral optic canal was cleared off the tumor. Multilayered reconstruction was achieved with fat, fascia, bone, flap, and glue.
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Video Timeline with Audio Transcript
0.8 min: Clinical Presentation
A 46-year-old woman presented with decreased vision on both sides for 1 year and a headache for 3 months. On examination of vision, there were just hand movements close to the face.
0.21 min: Neuroimaging [Figure 1]
Figure 1: (a) MRI and (b) CTA showing densely enhancing 4 cm tuberculum meningioma with anterior dural tail adherent to Acom complexContrast MRI showed a densely enhancing extra-axial mass lesion suggestive of meningioma of maximum dimension 4 cm centered on the tuberculum, with anterior dural enhancement up to the planum sphenoidale. The tumor base was narrow in the coronal section, with no lateral dural tail. In CT angiography, the tumor was intimate with the Acom complex, with no complete encasement.
0.51 min: Rationale
Surgical excision is the standard of care. The endonasal approach prevents the handling of the optic pathway. Despite being large, there is only an anterior but no lateral dural tail (narrow coronal base). Though adherent to the Acom complex, there is no complete encasement.
1.08 min: Description of the Setup
The patient was supine, with the head end elevated 30°, fixed using a skull clamp in mild neck extension. 4K endoscope system with 0° and 30° scopes, navigation, and high-speed drill were used.
1:25 min: Key Surgical Steps: The 10 D's
Delineation of vascularized flapDrilling of skull baseDurotomyDevascularizationDecompressionDetachmentDissectionDelivery of tumorDisengaging tumor from the optic canalDesign of skull base reconstruction.1.44 min: The procedure was started with a 0° scope. The nasal cavities were decongested with adrenaline-soaked sponges. The right middle turbinate is coagulated at the base and excised. The vascularized nasoseptal flap was marked using hook monopolar cautery. The superior incision was inferior to the sphenoid ostium, avoiding injury to the olfactory region. The posteroinferior incision is made along the border of the septum and the nasal floor. Both the incisions were joined vertically; the flap was dissected off the osseocartilaginous septum and placed in the oropharynx. Posterior septectomy was performed, preserving the bone graft for reconstruction. Nasoseptal mucosa along the corridor was cleared, and hemostasis was achieved using a coblator.
2.41 min: A wide sphenoidotomy and posterior ethmoidectomy incorporating superior turbinates were performed using rongeurs and a high-speed drill. The sphenoid's rostrum, keel, and septa must be removed for good instrument maneuverability and to prevent dead space under the flap. The mucosa of the sinuses was stripped off completely to avoid postoperative secondary mucocele. Under CT angiography and MRI navigation guidance [Figure 2],[5] the area of the tuberculum and planum under the tumor was drilled out, with the medial optico-carotid recess and the carotids as the lateral limit.
Figure 2: Intraoperative navigation based on MRI and CTA helps determine the extent of exposure3.24 min: After ensuring adequate binostril exposure, the dura was incised, with incremental devascularization and decompression initiated in the midline base of the tumor using a coblator, curettes, aspirator, through-cutting forceps, and knife, depending on the consistency. Henceforth, a 30° scope was kept on the floor of the right nostril, angulated upwards, and fixed on a rigid holder along with an irrigation system. At the same time, suction was positioned cranial to the scope, and other instruments were inserted through the left nostril. After coring the central portion, the lateral and anterior parts of the tumor were gently disconnected from the surrounding dura.
4.17 min: As the tumor was too fibrous to undergo extensive early internal decompression, dissection was started meticulously from the posteroinferior pole in the extra-arachnoidal plane using bimanual techniques. The dissected tumor fragments were intermittently excised piecemeal to clear the way toward exposing optic chiasm and A1 segments of the anterior cerebral artery [Figure 3] and [Figure 4]. Care was taken to protect the perforators. Only after exposing A1 segments, the dissection was extended circumferentially on either side. Aided by the optics of rotating the 30° scope, the tumor was gently rolled toward the center with angled instruments, keeping the suction tip as a counter traction to avert any neurovascular injury.
Figure 3: Right-angled view showing the interface between the tumor and pituitary stalk, right superior hypophyseal artery, ICA (internal carotid artery), optic pathway, and right A1 (anterior cerebral artery) with dissection proceeding postero-anteriorly
Figure 4: Left-angled view showing the interface between the tumor and pituitary stalk, left superior hypophyseal, ICA (internal carotid artery), optic pathway, and left A1 (anterior cerebral artery)5.20 min: The arachnoid over the pituitary stalk was preserved along with hypophyseal vessels. Dissection was the most prolonged phase of the surgery. It was carried out patiently with micro-rolling maneuvers, keeping the arachnoid layer over the vessels intact and, “bit by bit” tumor removal progressively making the tumor smaller and smaller.
5.46 min: The tumor was delivered incrementally so that further, deeper visualization could confirm any residual attachment [Figure 5]. The Acom complex was the last to come into view, as it was directly posterior to the tumor and intimately associated with the capsule [Figure 6]. Protecting the Acom complex with a long curved flat dissector, the capsule was gently peeled away.
Figure 5: Anterior angled view showing the interface between the superior surface of the tumor and both A2 (anterior cerebral arteries)
Figure 6: Acom (anterior communicating artery) adherent to the tumor capsule6.15 min: Once the capsule was confirmed to be free all around, it was gently mobilized out. The last remaining attachment to the lateral tuberculum dura was separated carefully, leaving no residue. The dural attachment was coagulated anterolaterally, and tumors in both optic canals were scooped out using angled visualization. In the end, both optic nerves, optic chiasm, anterior circulation vessels, and pituitary stalk were seen clearly [Figure 7]. ICG (indocyanine green) angiography revealed intact sub-chiasmatic and hypophyseal vessels.
Figure 7: Normal and ICG (indocyanine green) view of the operative area after tumor removal showing optic chiasm, pituitary stalk, Acom complex, and superior hypophyseal arteries7.03 min: Skull base reconstruction was performed in a multilayer. An appropriate size fat lobule and fascia lata harvested from the patient's thigh were placed one after the other in the operative cavity, with the bone graft forming a gasket seal and covered by the vascularized nasoseptal flap. Fibrin glue was applied over the top, and a piece of absorbable gelatin sponge reinforced the construct.
7.32 min: Outcome
The vision improved in the postoperative period. There was no CSF (cerebrospinal fluid) leak. MRI showed no residual or recurrence [Figure 8] till one year of follow-up.
Pearls and pitfalls
Endonasal endoscopy provides a direct approach to the skull base meningiomas. Such tumors can be de-vascularized even at the beginning of the surgery, which provides a relatively bloodless operative field. Initial tumor decompression facilitates the creation of a plane from the optic apparatus. Using an angled endoscope further helps detect residual tumors along the optic canal. Endoscopic excision of tuberculum sella meningiomas has better visual outcomes in the postoperative period.[6] Case selection is essential as tumors encasing carotids and perforators pose a significant challenge in achieving gross total excision with the risk of added complications. Also, while lateral parts of the dome can be rolled and excised, the tumor base extending laterally to the optic nerve, ICA, or lamina papyracea is a contraindication, wherein we prefer the supraorbital keyhole approach.[7],[8],[9] Further, closure of the skull base defect is an important step to prevent CSF leak.
Discussion
Tuberculum sella meningiomas are benign neoplasms growing close to the optic nerve, optic chiasm, anterior cerebral vessels, and branches. With time, they present with features of optic nerve/chiasm compression. Though they maintain a plane of arachnoid layer from these vital structures, their safe excision preserving the surrounding critical neuro-vascular structures is challenging. As the endonasal route provides a direct approach to these tumors, initial tumor decompression can be performed to safeguard the adjacent neurovascular structures. Again, an angled endoscope offers a better view of the displaced optic nerves laterally and facilitates tumor excision from the optic canal. These contribute to a better postoperative visual outcome and extent of resection. Large tumors extending lateral to the carotid artery and engulfing anterior circulation vessels are the significant contraindications for endoscopic surgery, where transcranial surgery is still considered best. A major disadvantage is the risk of CSF leak in the postoperative period.[7] However, the leak rate has reduced significantly with the use of vascularized naso septal flaps, multilayer closure, and experience.
ConclusionThe 10 D steps, as elucidated here, are safe and effective during endonasal endoscopy for tackling even a giant tuberculum sella meningioma without a lateral dural tail.
Informed consent
A full and detailed consent from the patient/guardian has been taken. The patient's identity has been adequately anonymized. If anything related to the patient's identity is shown, adequate consent has been taken from the patient/relative/guardian. The journal will not be responsible for any medico-legal issues arising out of issues related to patient's identity or any other issues arising from the public display of the video.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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