Surgical Management of Tuberculum Sellae Meningioma: Our Experience and Review of the Literature
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.333529
Source of Support: None, Conflict of Interest: None
Keywords: Endoscopic endonasal surgery, meningioma, tuberculum sellae
Tuberculum sellae (TS) meningiomas are a distinct subgroup of the suprasellar meningiomas that constitute approximately 5%–10% of all intracranial meningiomas. These tumors arise from the dura of the TS, and tend to grow in the prechiasmatic and/or subchiasmatic spaces by displacing the optic nerves superiorly and laterally. Although majority of patients present with headaches, nearly 67%–77% TS meningiomas invade the optic canals and cause significant visual impairment by compressing the optic nerves and chiasm.,,, The primary goal of treatment for these tumors, therefore, remains restoration of vision and gross total resection of tumor to prevent recurrence.
Resection of TS meningiomas presents a great surgical challenge because of the close anatomical proximity to vital neurovascular structures, including the optic nerves/chiasm, internal carotid artery (ICA) and its branches, pituitary gland, infundibulum, and hypothalamus. Several conventional transcranial (TCA),,,,,,,,, and endoscopic endonasal (EEA),,,,,,,, approaches have been described in the literature with successful surgical outcome and minimum complications. However, despite good surgical results, no clear consensus has yet been reached on which approach provides the best results, and controversies still exist regarding the selection criteria of the most optimal surgical approach for TS meningiomas.
In this retrospective study, we present our experience in the management of TS meningiomas in 62 consecutive patients and discuss the safety and efficacy of the available surgical approaches and evaluate the postoperative outcome with regards to total tumor removal and visual recovery. We also analyze clinical features, tumor characteristics, and anatomical factors that might influence the selection of an appropriate surgical approach and postoperative outcome.
Medical records of all patients with TS meningioma who underwent surgery at our institutions between January 2005 and December 2018 were reviewed retrospectively. Patients with meningiomas arising from the clinoid processes, medial sphenoid wing, olfactory groove, and planum sphenoidale were excluded from this study. Patient demographics, imaging findings, operative records, and postoperative clinical and radiographic outcomes were analyzed in detail. Indications of surgery included progressive headaches/raised intracranial pressure signs, and/or visual impairment. All tumors with larger attachment at the base (>3.0 cm) and/or those with lateral extensions were considered for TCA surgery. EEA surgery was offered to the patients who had purely midline tumors and/or smaller tumor attachment at the base (<3.0 cm). Pre- and postoperative clinical evaluation included a detailed neurological examination with a formal visual field (Goldman perimetry) charting and visual acuity tests (Snellen chart). Neuroimaging with contrast computed tomography and magnetic resonance (MR) imaging was used for initial preoperative evaluation and selection of the optimal approach, as well as for the assessment of postoperative outcome.
Clinical and endocrinological outcomes were evaluated at 3–4 weeks postoperatively. Radiographic evaluation with MR imaging was done at 3–4 months after surgery, and annually thereafter. The extent of tumor removal was determined on findings of the operation record and postoperative MR imaging, and was classified as gross total (100% tumor removal in the operation record and no residual tumors on MRI), near-total (>90% tumor removal in the operation record and small residual on MRI), and subtotal (<90% tumor removal in the operation record and a visible mass in the surgical field on MRI) resection.
Three standard TC approaches, including bilateral subfrontal craniotomy,, [Figure 1], pterional craniotomy,, [Figure 2], and supraorbital craniotomy,,, [Figure 3], and the extended (transplanum-transtuberculum) EEA approach,,,,,,,,,,,, [Figure 4] were used for tumor removal in this study.
There were a total of 62 patients, 46 (74%) females and 16 (26%) males, with a mean age of 41.9 years (range, 28-73 years). The most common presenting symptom was impairment of vision, which was observed in 54 (87%) patients, followed by headache in 25 (40%), cognitive decline in 2 (3.2%), and seizures and dementia in 1 (1.6%) each patient. Tumor size varied from 23 to 58 mm in diameter. Surgical approaches used in 62 patients included 38 craniotomies (TCA), [bilateral subfrontal in 10 (16%), pterional in 23 (37%), and supraorbital in 5 (8%)], and extended endonasal endoscopic (transplanum-transtuberculum) approach in 24 (38.7%) patients. Tumor characteristics in patients were different and specific in each surgical subgroup, and therefore, operative results were not truly comparable.
Gross total tumor removal was achieved in 53 (85.5%), near-total in 7 (11.3%), and subtotal in 2 (3.2%) patients. The rates of GTR varied from 84.2% in TCAs (80% in bifrontal, 87% in pterional, and 80% in supraorbital), to 87.5% in EEA [Table 1]. Of two patients with subtotal tumor removal, one patient had a large tumor with lateral extension in the adjacent cavernous sinus region. The goal of EEA surgery in this 73-year-old man was to achieve adequate decompression of the optic apparatus. The second patient, a 40-year-old woman, received bifrontal craniotomy for removal of her large tumor which was extending into the sella and optic canals and was encasing the carotid and anterior cerebral arteries. Her postoperative images revealed a residual tumor mass in the optic canal and along the vessels, which was treated with adjuvant radiotherapy 5 months later when tumor progression was diagnosed.
Overall, postoperative improvement or stabilization in vision was reported in 53 (85.5%) patients, including 79% in TCA and 96% in EEA groups [Table 2]. Nine (14.5%) patients experienced visual worsening after surgery, 8 (21%) from TCA, and 1 (4.2%) from EEA groups. Complications in the TCA group included anosmia in 8 patients, diabetes insipidus in 3, seizures in 2, CSF leak and meningitis in 1, SIADH in 1, CN III palsy in 1, vascular injury and altered sensorium in 1, periorbital swelling in 1, and wound infection in 1 patient [Table 2]. The main complication in the EEA group was CSF rhinorrhea which occurred in 9 (37.5%) patients, and 4 of them required a second surgery for reconstruction. With increased experience and continuous attempts to improve closure techniques over the years, we have managed to reduce the rate of postoperative CSF leak significantly in EEA (currently <5%). At a mean follow-up of 24 months, 3 patients developed recurrence of tumors and were treated with surgery, radiotherapy, and only observation, respectively.
A review of the literature suggests that aggressive surgical removal of TS meningioma, including removal of the involved dura and underlying hyperostotic bone, offers the best chance to achieve Simpson Grade I resection and to prevent recurrence of the tumor.,,,,, Surgery also remains the optimal strategy to restore failing vision due to compression of the visual apparatus by a tumor. However, meningiomas in this region generally pose a difficult challenge to the surgeons due to their critical location and proximity with the vital neurovascular structures at the base of the skull. Traditionally, numerous midline and lateral TC approaches, including bifrontal, interhemispheric, extended bifrontal, pterional, subfrontal, orbitozygomatic, and keyhole supraorbital craniotomies have been described for surgical removal of these tumors.,,,,,,,,,, Since the first description of the extended endoscopic transnasal removal of a meningioma by Weiss and coworkers in 1987, there has been a steady increase in interest in using this approach for resection of the parasellar and anterior skull base tumors including TSMs.,,,,,,,,,, With recent advances in the optical technology and modifications in surgical techniques like the expanded endonasal exposures, EEA has now emerged as an effective surgical option for properly selected TS meningiomas.
Gross total removal of tumor
The rate of total surgical removal of TS meningiomas varies between 60%-100% in the literature. [Table 3] and [Table 4] It is often difficult to compare surgical outcomes from different series because of the lack of uniformity in the criteria used for estimation of the degree of tumor resection. However, in a comparative study from a single institution, de Devitiis et al. reported that the rate of tumor resection is almost similar in the two surgical approaches for TS meningiomas, 83.3% GTR with TCA and 86.4% with EEA. In two other studies on TS meningioma surgery, Kong et al. and Bander et al. reported that the postoperative outcome results in the TCA groups were similar to those in EEA groups. We used standard criteria in our study to evaluate extent of tumor resection in 62 patients, and the rates of GTR were 84% and 87.4% in TCA and EEA groups, respectively.
The endonasal endoscopic approach offers several advantages over TCAs when used for the removal of suprasellar meningiomas. Firstly, it provides a wide and panoramic endoscopic view of the entire suprasellar region medial to the carotid arteries and optic nerves, which is necessary for safe and radical removal of meningiomas.,,, Since the trajectory is from below the optic apparatus, this approach allows excellent visualization of the tumor and the important small perforating arteries at the infrachiasmatic region, an area that is difficult to visualize from above via a TCA. Furthermore, because the dural feeding branches from McConnell and posterior ethmoidal arteries take their course from below, the tumor devascularization can be performed more effectively through endonasal route. This facilitates safe and complete tumor removal with significant reduction in blood loss and operative time. Lastly, EEA is a relatively lesser invasive procedure with faster postoperative recovery and shorter hospital stay., Results of most of the recent studies suggest that the EEA approach is safe and excellent outcomes can be achieved when used in patients with TS meningiomas.,,,,,,,,, Severe postoperative morbidities commonly associated with TCAs are less frequently seen with endonasal skull base approaches. Moreover, EEA is associated with a significantly lower incidence of anosmia, which occurs mainly due to stretch injury to the olfactory tracts and nerves and is observed in > 30% of cases with TCAs.,
It is evident from the current literature that the tumor characteristics like large size, intracranial extensions, and its intimate relationship with the optic apparatus and adjacent vascular structures influence the rate of radical tumor resection.,,,,,,,, With GTR rates of over 92% using TCA approaches, as compared to 50%-84% with the endonasal approach, the recent publications clearly favor the role of TCA in larger and more complex tumors.,,,,, However, there is no similar consensus available on the optimal surgical approach for TS meningiomas of smaller/medium size, and simple configuration. It is also worth noting that there is a bias among neurosurgeons towards selecting EEA for smaller midline tumors, and TCA for larger ones. The best way to address this issue would be to do a direct comparison of the results of TCA surgery for TS meningiomas that are considered suitable for EEA by surgeons of equal expertise and experience.
Mortazavi, Sekhar, and coworkers identified six clinical parameters, including tumor size (<2 to > 4 cm), optic canal involvement, vascular encasement, brain invasion, previous surgery, and prior radiation, that may influence postoperative results in patients with TSM. Based on these parameters, the authors proposed a classification system to predict surgical risk, clinical outcome, and recurrence, and to guide the surgeon to choose a TCA or EEA. According to the authors, a patient with a tumor < 2 cm, no or minimal vascular encasement, and minimal extension into the optic canals can undergo endoscopic transsphenoidal resection, whereas a patient with brain invasion, >180° vascular encasement, >4 cm in size, and severe optic canal involvement is better suitable for TCA. Using multiple regression analysis, Mascarella et al. reported that the factors associated with incomplete surgical resection of TSM via an EEA include the presence of hyperostosis, cavernous ICA involvement, and long dural tail in the transverse plane. The authors developed a scoring system that had a sensitivity of 85.5% CI (42.1–99.6) and specificity of 100% CI (81.5%–100). Magill et al. studied the size of the tumor origin at the tuberculum region, along with the involvement of the adjacent optic canal (s) and anterior cerebral vessels in a series of patients, and proposed a tumor grading scale, according to which, a higher tumor score was found to be associated with a higher risk of incomplete tumor resection.
Most smaller and medium-sized suprasellar meningiomas located in the midline are treated with EEA at our institution. We consider the extent of tumor origin at the skull base, and not the height or vertical dimension of the tumor in the midline, as the crucial parameter for choosing the endoscopic transsphenoidal approach. Our experience shows that the midline tumors that are upto 3.0 cm in height in the vertical plane can be removed safely and radically from below using EEA, provided their attachment area at the base is <3.0 cm and does not extend lateral to the ICAs or anterior clinoid processes on either side. Seven patients in this study had their tumor height varied between 3.0-3.3 cm in the midline but were selected for EEA because the area of tumor attachment at the TS was smaller than 3.0 cm. A complete tumor removal was achieved by using EEA in all 7 cases without any additional difficulty or risk. In cases with wide-base meningiomas that have dural extensions laterally over the optic canal and orbital roof, we prefer a TCA route.
Nearly 67%–77% of TS meningiomas extend into one or both optic canals.,,, Removal of the entire tumor with its intracanalicular part is, therefore, a standard surgical strategy to prevent a recurrence.,, Endoscope works as an extremely useful adjunct in this situation as it provides a direct view of the optic canal which can be opened widely from below, and a safe and complete tumor resection can be performed using a bimanual microsurgical technique, even when the tumor is involving the optic canals on both sides.,,,,,, Occasionally, the intracanalicular tumor is circumferential or extended in the superior or lateral parts of the optic canal and the optic nerve is pushed down into the lower part of the optic canal. We avoid EEA in such cases and prefer to remove the tumor by unroofing the optic canal from above through a supraorbital or pterional approach.
Another situation where an EEA can be advantageous is when the tumor is extending down into the sella or sphenoid sinus.,, Access to this region is extremely difficult with TCA approaches, resulting in failure to achieve complete tumor removal, even after considerable brain retraction and manipulation of the optic nerves. The endonasal approach provides an opportunity to successfully remove the tumor extension as well as the involved dura and the hyperostotic bone. When the tumor is extending into the anterior cranial fossa, the exposure is usually enlarged further anteriorly by drilling the posterior part of the planum sphenoidale and the tumor is removed completely with its dural tail. However, further anterior extension of the exposure in the skull base may risk injury to the olfactory nerves and tracts, and therefore should be avoided if the patient's olfaction is intact. In such cases, we consider an alternative approach like supraorbital keyhole craniotomy.
Bilateral frontal lobe edema/injury on the preoperative MR imaging is not uncommon in TS meningiomas, and when present, has a potential to aggravate during TCA surgery due to retraction of the brain retraction. The endonasal approach avoids brain handling and thus allows safe removal of tumors without frontal lobe injury. Patients who are elderly or medically unfit are not good candidates for TCA surgery because of its longer duration, and a higher risk of blood loss and brain retraction. The endonasal approach can be considered as a better alternative surgical approach in these cases, particularly when the goal of surgery is tumor decompression and not GTR.
Visual impairment is the most common presenting symptom in patients harboring meningioma of TS, and a majority of patients usually show significant improvement after surgery.,,,, Recent studies with direct comparison of results demonstrate significantly higher rates of visual recovery with EEA (90%-96%) and relatively increased visual worsening with the TCA approaches (19%).,,,,,,, In a meta-analysis study comparing visual outcomes, visual improvement was observed in 75% and 58.4% of cases with EEA and TCA, respectively. In our study, the visual outcome was significantly superior in EEA group (96%) as compared to the TCA group (79%) and the visual worsening occurred in 9 patients (14.5%), 21% with TCA and 4% with EEA.
The visual outcome mainly depends on several factors, including the tumor size, duration and degree of optic nerve compression, presence/absence of tumor in the optic canal, state of the normal blood supply to the optic apparatus, and magnitude of surgical manipulations of the optic nerve during tumor removal. According to Fahlbusch and Schott and Raco et al., the size of the tumor is critical for visual recovery and it influences the visual outcome significantly. In their study, patients with tumors smaller than 30 mm had a better visual outcome as compared to those with tumors larger than 30 mm. Reporting surgical results in patients with TSMs, Nakamura et al. mentioned that 16% of cases with tumors smaller than 30 mm in diameter in their series had significant improvement in their vision postoperatively, as opposed to 9.7% cases with tumors >30 mm. They also suggested that the larger the tumor size, the higher is the risk for visual worsening postoperatively. According to the tumor grading scale proposed by Magill and associates, larger tumors i.e., those with >17 mm in size and optic canal invasion have higher tumor score and therefore have poor rates of visual outcomes, when compared with the smaller tumors with lower tumor score. In a clinical study of 100 cases of TSM, Lee and colleagues demonstrated that the origin of TSM is an important prognostic factor and that it was located at the one lateral end of the TS in 85% of patients in their study. The authors concluded that the laterality of tumor origin, along with the preoperative duration of symptoms, and optic atrophy, was associated with long term poor outcome. In our series of 62 patients with tumor size varying between 2.3 and 5.8 cm, the overall rate of visual improvement was 85.5%.
The risk of postoperative visual impairment has been reported as 8%–42% in various studies.,,,, Most authors attribute this to the direct surgical trauma and/or disturbance in the vascular supply of the optic chiasm and nerves during the operation. The optic nerves and chiasm are especially vulnerable to compromise in their normal blood supply via small subchiasmatic perforating arteries which are difficult to visualize from a suprachiasmatic view provided by the TCA approach from above.,, When approached endonasally from below, surgical manipulation of the optic nerves and chiasm can be avoided or reduced to a minimum, and the vascular supply to the undersurface of the optic apparatus can be preserved more effectively under direct vision.
Failure to remove a tumor from the optic canal is one of the most common causes of persistent visual loss or deterioration. The tumors most often occupy the inferomedial aspect of the canal which is difficult to access from above through a TCA approach. An endonasal approach from below offers a straight corridor for removal of the intracanalicular tumor and also allows dissection for a 270° release of the optic nerve under direct vision. TS meningiomas are occasionally associated with few anatomical anomalies of the sphenoid sinus, such as pneumosinus dilatans. When present, it poses a difficult surgical problem because of its high-lying position that requires more vigorous brain retraction when approached via a TCA route., The endonasal approach from below provides a safe and more effective route to access the TS meningiomas without any additional risk when this particular anatomical variation coexists.
The tumor consistency, however, appears to substantially influence the extent of its removal when endonasal endoscopic approach is used., While the soft and suckable tumors can be removed with a relative ease, firm or fibrous tumors are usually difficult to remove through EEA, often resulting in either incomplete resection or switching over to a trancranial approach. Recently, there has been a growing interest in the use of MR technology to predict meningioma consistency, especially soft or firm/fibrous, which may have immense impact on the preoperative planning, patient counseling, and intraoperative decision-making.,,
The most common complication after EEA surgery for TS meningiomas is cerebrospinal fluid (CSF) leak. The rate of CSF leak generally ranges from 10% to 43% in most EEA series.,,,,,,, Most of the studies with high CSF leaks are old and published before the routine use of a vascularized nasoseptal flap for skull base reconstruction. Recent reports have demonstrated significantly reduced CSF leak rates, mostly below 5.4% when reconstruction is performed with a pedicled nasoseptal flap., The overall incidence of this complication in our series was 37.5%, which could most probably be due to a much higher occurrence of CSF leakage in the initial part of our endonasal surgery experience. However, by improving our technique of closure using multilayered reconstruction together with Hadad-Bassagasteguy vascularized nasoseptal flap, we have managed to bring it down considerably in past few years. During our initial experience with EEA in the first 3 years of this study the postoperative CSF rhinorrhea was observed in all 6 patients, which subsequently reduced to 3 in 13 patients in the next 7 years. No one of our 5 consecutive patients in the last 3 years had CSF leakage following endoscopic transsphenoidal surgery for TS meningioma.
The recent addition of few relatively lesser invasive surgical techniques like endonasal endoscopic transtuberculum approach and supraorbital keyhole minicraniotomy using an eyebrow skin incision, in the already existing traditional TCA approaches, has enhanced the efficacy and safety of surgery for meningiomas of TS. Because each approach has unique advantages and disadvantages, the choice to use an endonasal or TCA approach must be based on the specific characteristics of each case. Careful patient selection and surgeon's comfort with one approach over the other are the two most important factors to determine optimal surgical strategy. We prefer EEA for all midline tumors which are located medial to the internal carotid arteries with their dural attachment not extending laterally to clinoid processes. Meningiomas extending into the optic canals, sella turcica, sphenoid sinus, or anteriorly to the planum sphenoidal region are also suitable in our opinion for removal through EEA. Alternative approaches like pterional or supraorbital craniotomy should be considered for tumors that are firm/fibrous in consistency, extend laterally beyond the ICA, or involve the anterior cerebral arteries. The bifrontal approach is reserved for those tumors that present with larger area of attachment and lateral extensions on both sides, bilateral optic canal invasion, and severe vascular encasement. Risks of anosmia should be evaluated on a case-to-case basis while selecting the surgical approach.
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The authors certify that all appropriate patient consent has been obtained. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]