Tuberculum sellae meningiomas are challenging lesions; their critical location and often insidious growth rate enables significant distortion of the superjacent optic apparatus before the patient notices any visual impairment. This article describes the technical nuances, selection criteria and complication avoidance strategies for the endonasal resection of tuberculum sellae meningiomas. A stepwise description of the surgical technique is presented; indications, adjuvant technologies, pitfalls and the relevant anatomy are also reviewed. Tuberculum sellae meningiomas may be safely and effectively resected through the endonasal route; invasion of the optic canals does not represent a limitation.
Key points
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Nearly all tuberculum sellae meningiomas are amenable to endonasal resection; lateral extension beyond the internal carotid arteries is the major limitation to resection.
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Vascular encasement or optic canal invasion increases the complexity of the surgery but is not a limitation of the approach.
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Potential advantages of the approach include the absence of neurovascular retraction or displacement, increased visibility underneath the optic apparatus, and removal of infiltrated hyperostotic bone.
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The main disadvantages include the risk for cerebrospinal fluid leakage, need for dedicated training and equipment, and steep learning curve.
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The endonasal approach for removal of tuberculum sellae meningiomas requires a wide transnasal corridor, with removal of the right middle turbinate, posterior ethmoidectomies, resection of the posterior third of the septum for creation of a single working cavity, and elevation of a pedicled nasoseptal flap.
Introduction
Tuberculum sellae meningiomas are challenging lesions; located in the suprasellar space, they can displace and distort the superjacent optic apparatus causing visual impairment, encase critical neurovascular structures, and promote hyperostosis and optic canal invasion. These features render their safe resection a daunting task. Historically, this has been accomplished through open transcranial approaches, especially the classic pterional-transsylvian route or through more complex skull base approaches, such as the cranio-orbito-zygomatic and its variants and even the fronto-basal interhemispheric technique. More recently, less invasive methods also have been proposed, including the lateral supraorbital and the “eyebrow” subfrontal craniotomies. Regardless of which technique is chosen, all transcranial routes require a certain degree of cerebral retraction; in some instances, even some manipulation of the optic apparatus is necessary for tumor removal, especially the component located underneath the chiasm and ipsilateral optic nerve, often demanding “blind” curettage of that space. Furthermore, given the pattern of growth typical of these lesions, rising from the tuberculum arachnoid and projecting upward and posteriorly, the superior hypophyseal arteries are often displaced along with the tumor capsule and are thus directly in the surgeon’s angle of attack, demanding the dissection to take place within an even tighter window.
The past decade witnessed several technological advances in skull base surgery, the most important of which arguably is the rise of endoscopic endonasal surgery. When applied to tuberculum sellae meningiomas, expanded endoscopic endonasal approaches (EEAs) seem to present several advantages: the need for cerebral retraction is obviated, given the ventral angle through which the surgeon tackles these lesions; because the optic apparatus is displaced superiorly and posteriorly, it is involved only in dissection at the end stages of surgery, during release of the tumor capsule from the optic nerves themselves, thus lowering the amount of optic manipulation. Moreover, because the superior hypophyseal arteries are also typically dislodged toward the optic chiasm, freeing them from the tumor capsule is also facilitated and takes place only at the end of tumor removal, with minimal handling. Based on these potential features, EEAs have become the workhorse for the authors in nearly all suprasellar tumors, meningiomatous or otherwise.
Hence, herein we describe our current indications and contraindications, surgical technique and anatomy, as well as complication management and avoidance strategies for the endoscopic endonasal resection of tuberculum sellae meningiomas.
Indications/contraindications
For indications and contraindications, see Table 1 .
| Indications | Contraindications | |
|---|---|---|
| Relative | Absolute | |
|
| |
a Treat for 3 weeks (if bacterial) or 6 weeks (if fungal) before proceeding with endonasal surgery.
b Endonasal surgery may be an option if optic decompression is the goal in cases in which total resection is not feasible (ie, bilateral cavernous sinus invasion); if extension beyond the ICA is unilateral and there is no cavernous sinus invasion, consider transcranial surgery.
Introduction
Tuberculum sellae meningiomas are challenging lesions; located in the suprasellar space, they can displace and distort the superjacent optic apparatus causing visual impairment, encase critical neurovascular structures, and promote hyperostosis and optic canal invasion. These features render their safe resection a daunting task. Historically, this has been accomplished through open transcranial approaches, especially the classic pterional-transsylvian route or through more complex skull base approaches, such as the cranio-orbito-zygomatic and its variants and even the fronto-basal interhemispheric technique. More recently, less invasive methods also have been proposed, including the lateral supraorbital and the “eyebrow” subfrontal craniotomies. Regardless of which technique is chosen, all transcranial routes require a certain degree of cerebral retraction; in some instances, even some manipulation of the optic apparatus is necessary for tumor removal, especially the component located underneath the chiasm and ipsilateral optic nerve, often demanding “blind” curettage of that space. Furthermore, given the pattern of growth typical of these lesions, rising from the tuberculum arachnoid and projecting upward and posteriorly, the superior hypophyseal arteries are often displaced along with the tumor capsule and are thus directly in the surgeon’s angle of attack, demanding the dissection to take place within an even tighter window.
The past decade witnessed several technological advances in skull base surgery, the most important of which arguably is the rise of endoscopic endonasal surgery. When applied to tuberculum sellae meningiomas, expanded endoscopic endonasal approaches (EEAs) seem to present several advantages: the need for cerebral retraction is obviated, given the ventral angle through which the surgeon tackles these lesions; because the optic apparatus is displaced superiorly and posteriorly, it is involved only in dissection at the end stages of surgery, during release of the tumor capsule from the optic nerves themselves, thus lowering the amount of optic manipulation. Moreover, because the superior hypophyseal arteries are also typically dislodged toward the optic chiasm, freeing them from the tumor capsule is also facilitated and takes place only at the end of tumor removal, with minimal handling. Based on these potential features, EEAs have become the workhorse for the authors in nearly all suprasellar tumors, meningiomatous or otherwise.
Hence, herein we describe our current indications and contraindications, surgical technique and anatomy, as well as complication management and avoidance strategies for the endoscopic endonasal resection of tuberculum sellae meningiomas.
Indications/contraindications
For indications and contraindications, see Table 1 .
| Indications | Contraindications | |
|---|---|---|
| Relative | Absolute | |
|
| |
a Treat for 3 weeks (if bacterial) or 6 weeks (if fungal) before proceeding with endonasal surgery.
b Endonasal surgery may be an option if optic decompression is the goal in cases in which total resection is not feasible (ie, bilateral cavernous sinus invasion); if extension beyond the ICA is unilateral and there is no cavernous sinus invasion, consider transcranial surgery.
Surgical anatomy
The surgical anatomy and spatial relations of the ventral skull base and the suprasellar space have been described in detail ; the main pertinent structures and landmarks are depicted in Fig. 1 .
Surgical technique
Preoperative Planning
All patients submitted to endonasal resection of tuberculum sellae meningiomas undergo the following:
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Anesthesia evaluation with nasal swab and culture; if positive for methicillin-resistant Staphylococcus aureus (MRSA), the patient is treated in the morning of surgery with a single nasal application of a povidone-iodine solution at 5% (3M, St. Paul, MN).
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Magnetic resonance imaging (MRI) of the brain and computed axial tomography (CT) scan, both thinly sliced (<3 mm) and fused for intraoperative navigation. Special attention is given to the position of the pituitary stalk, the anterior cerebral arteries, and the presence of hyperostosis and/or optic canal invasion.
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Full pituitary hormone serum sampling, including growth hormone, prolactin, thyroid-stimulating hormone, cortisol, adrenocorticotrophic hormone, testosterone, follicle-stimulating hormone, and luteinizing hormone. This aims to establish preoperative endocrine dysfunction, if any.
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Ophthalmologic evaluation with visual field testing.
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Otolaryngology evaluation, to detect sinonasal abnormalities, especially signs of infection.
Preparation and Patient Positioning
Preparation
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General anesthesia with orotracheal intubation: no cerebrospinal fluid (CSF) diversion is used.
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Prophylactic antibiotics: cefepime if MRSA negative, cefepime and vancomycin if MRSA positive.
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Urinary catheter placement.
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Copious nasal irrigation with oxymetazoline hydrochloride solution and facial/nasal decontamination with iodine solution; the abdomen is also prepped in case a fat graft is necessary.
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The navigation tower and at least 2 monitors are positioned according to the otolaryngologist’s hand dominance ( Fig. 2 ).
Fig. 2
Patient and room positioning. ( A, B ) Patient positioning. The head is secured on a Mayfield 3-pin headholder and slightly turned to the right; the neck is gently extended to improve the operating angle. Note that the abdomen is prepped in case a fat graft is necessary and the extensive foaming and taping to secure the patient. ( C, D ) Monitor positioning when the otolaryngologist is left-handed; 2 monitors flank the navigation tower at the head of the bed. The otolaryngologist stands to the left of the patient to drive the endoscope while the neurosurgeon, on the patient’s right, performs the tumor dissection. ( E ) Monitor positioning when the otolaryngologist is right handed; a monitor is placed to the left of the patient and another at the patient’s feet and both the otolaryngologist and neurosurgeon stand to the patient’s right.
Positioning
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Supine position, with the head fixed on the Mayfield 3-pin headholder. The neck is slightly extended and the head turned to the right, with the whole body tilted to the left (see Fig. 2 ). The body is secured and protected with foam and tape; the navigation transmitter is attached to the headholder.
Surgical Approach
The surgical approach is composed of the following sequential steps ( Fig. 3 ):
- 1.
Right middle turbinectomy, performed with curved strong sinus scissors.
- 2.
Bilateral posterior ethmoidectomies, performed with microdebrider.
- 3.
Elevation of the nasoseptal flap and storing in the nasopharynx (side is decided based on local anatomy but preferably on the right side to avoid conflict with power instruments on the left nostril from a right-handed surgeon).
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Posterior septectomy.
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Incision and rotation of the now-exposed contralateral septal mucosa to cover the denuded septum.
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Wide bilateral opening of the sphenoid sinus with Kerrison rongeurs and high-speed drill; extreme care is taken not to damage the pedicle of the nasoseptal flap.
Surgical Procedure
The surgical procedure is composed of the following sequential steps ( Fig. 4 ):
- 1.
Drilling of the sphenoidal septae and skull base; the bone is drilled down to eggshell thickness and elevated from the dura. This starts at the sella, followed by the planum sphenoidale (a trapezoid-shaped osteotomy is performed and the planum is elevated in a single piece) and finally the tuberculum.
- 2.
Coagulation of enlarged dural vessels to promote tumor devascularization (there are often large McConnell capsular arteries associated with tuberculum sellae meningiomas).
- 3.
Dural opening starts at the midline of the suprasellar space and is carried superiorly to the SICS, which is visualized but not ligated. The dural opening is extended laterally above the SICS to expose the base of the tumor and to determine the position of the pituitary gland. This plane is followed posteriorly to encounter the pituitary stalk.
- 4.
Tumor biopsy and debulking can be achieved with microscissors and aspiration or with the use of side-cutting aspiration devices. We have decreased the use of ultrasonic aspirators in endonasal surgery because of the risk of heat damage to the nostrils.
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Extracapsular dissection: microsurgical principles are always respected and the arachnoid envelope of the tumor is used to protect critical surrounding neurovascular structures, namely the superior hypophyseal arteries, the pituitary stalk, the optic nerves, and chiasm. Once the tumor remnant has been freed from these structures, it is “delivered” into the sphenoid cavity and removed. If too adherent or too voluminous, the tumor remnant may be resected in piecemeal fashion. It is imperative to ensure that the anterior cerebral arteries are not attached to the tumor capsule before mobilizing it.
- 6.
If optic canal involvement is present, the optic sheath (now exposed after drilling during the approach) is opened with angled scissors under angled endoscopic visualization; care is taken not to damage the ophthalmic arteries during dissection of this tumor component.
- 7.
Copious irrigation with warm saline clears the surgical field of blood and debris while promoting hemostasis.
- 8.
Multilayered reconstruction concludes the procedure; although several methods have been described, the authors currently use the following sequence: inlay collagen matrix, onlay nasoseptal flap, sphenoid filling with synthetic foam.
Related posts:
Endoscopic Endonasal Skull Base Surgery
Endoscopic Endonasal Extended Approaches for the Management of Large Pituitary Adenomas
Endoscopic Endonasal Repair of Spontaneous and Traumatic Cerebrospinal Fluid Rhinorrhea
Endoscopic Endonasal Approach to Ventral Posterior Fossa Meningiomas
Endoscopic Endonasal Odontoidectomy
Chordomas
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