Endoscopic Endonasal Approach for Tuberculum-Planum Sphenoidale Meningioma

Abstract

Meningioma is the most common type of primary brain tumor, accounting for approximately 30% of all brain tumors. Anterior skull base meningiomas represent 8.8% of all meningiomas. They can be in olfactory groove, planum sphenoidale, or tuberculum sellae region. Their approach is challenging, tuberculum-planum sphenoidale meningiomas are a subgroup that can be approached and resected by using an endoscopic endonasal corridor. The complex anatomy in relation to important neurovascular structures poses difficulties in the resection of these lesions endonasally. Moreover, surgically created skull base defect closure is crucial for prevention of CSF leaks. In this chapter, the technical nuances and outcome of this approach are described.

1. Introduction

Anterior skull base meningiomas originate from different locations (olfactory groove [OG], planum sphenoidale [PS], tuberculum sellae [TS], parasellar region, or anterior clinoid. Tuberculum sella and planum sphenoidale meningiomas represent 5–10% of intracranial meningiomas [1]. Its incidence is common in the fourth decade of life. Female is more affected than male by this tumor. Due to their anatomical location, tuberculum sellae meningiomas play a significant role in the compression of the optic pathway. TS meningioma classically presents with “the chiasmal syndrome”, a primary optic atrophy with bitemporal field defect due to variable compression on the optic pathway. PS meningiomas are located more anterior and in proximity to the olfactory groove location so visual disturbances are uncommon. The pituitary hormone functions usually remain within normal limits. In neuroimaging the sella remains normal as the tumor 0riginates exclusively from tuberculum sella and planum sphenoidale. Conventionally craniotomy and surgical decompression are the mainstay of treatment [2]. With the advancement of neuroimaging, neuro navigation, and optics, the endoscopic endonasal transsphenoidal approach is a favuorable surgical corridor for tuberculum sella and planum sphenoidale meningioma [3]. Without brain retraction and direct attack to the vascular supply, endoscopic endonasal transsphenoidal resection is a useful surgical option for TS and PS meningioma management as well as visual recovery [4].

In this chapter, the technical pearl and the outcome of endoscopic endonasal transsphenoidal approach for the management of TS and PS meningiomas will be described.

2. Materials and methods

Retrospective analysis of TS and PS meningioma which underwent endoscopic endonasal transsphenoidal approach. The surgical access was through transtubercular-transplanum corridor. In the study, there were a total of 12 cases in a period of 8 years. TS meningiomas were located on the small surface between the chiasmatic sulcus and diaphragm sellae, and PS meningiomas, those located more anteriorly (Figure 1a and b).

Figure 1.

(a) Tuberculum sella (TS) meningioma and (b) planum sphenoidale (PS) meningioma [5, 6].

All the patients in the study group had been examined preoperatively with computed tomography (CT) and magnetic resonance imaging (MRI) studies. Ophthalmological and endocrinological evaluations were done in all cases.

The indications for endoscopic approaches were tumors situated on TS-PS region in the midline with or without extension into the optic canal and vessel encasement. Those cases which underwent craniotomy, olfactory groove region tumor, a large tumor extending beyond the mid pupillary line were excluded both preoperatively and postoperatively.

In follow-up protocol clinical, radiological, and ophthalmological outcomes were recorded initially 3 monthly and 6 monthly for 2 years and then every year to rule out any recurrence. The outcomes were analyzed and recorded for each case individually.

3. Surgical steps

Preoperative counseling for the endoscopic endonasal approach was recorded as per standard protocol.

Anesthesia: General anesthesia with orotracheal intubation.

Position: Supine position. The head was fixed by Mayfield head clamp and tilted to the left (Figure 2).

Figure 2.

Position-supine and head were fixed by Mayfield head clamp.

Preparation of nasal cavity: Normal saline and chlorhexidine gluconate were used for antiseptic wash. For vasoconstriction, adrenalin (1:1000) soaked cottonoids were used for at least 5 min.

Instruments: 4-mm rigid endoscopes with 0°, 30°, and 70° angled lenses.

Steps: The patient together with the endoscopic/video camera equipment is draped with aseptic techniques. Fascia lata and free fat graft were prepared from the thigh. The vascularized nasoseptal flap (Hadad flap) was raised. The surgical corridor was created by doing middle turbinectomy, removal of both the posterior bony septum and anterior cartilaginous septum, shoulder osteotomy, and removal of the vomer. The mucosa of the sphenoid sinus was removed to expose the sellar anatomy. Intra-op vascular Doppler was used to locate the ICA-to-ICA area. An electric drill was used to remove the bony area of TS-PS region and expose the dura over the tumor base.

Removal of tumor: Endoscopic bipolar diathermy was applied for the devascularization of tumor from the base. The tumor was removed by standard microsurgery technique under endoscopic view with identification of tumor arachnoid interphase (Figure 3).

Figure 3.

Intraoperative removal of tumors (a) tumor arachnoid interphase and (b) delivery of tumor.

Closure of skull defect: Skull base defect reconstruction was done with fat, fascia lata, Haddad flap, and reinforced with platelet-rich fibrin. In some cases, we used middle turbinate as a vascularized flap (Figure 4).

Figure 4.

Reconstruction of skull base defect.

4. Results

4.1 Demography and Preop radiological findings

Table 1 shows the distribution of demography and prep radiological findings. Most of the patients were in the age group 31–40 years. There was female preponderance.

Case no	Age (year)	Sex	Radiological location
1	31	F	TS
2	35	M	TS; OC involvement; ICA encasement
3	36	F	TS; OC involvement
4	38	M	TS + PS
5	45	M	TS
6	48	F	PS;
7	50	F	PS;
8	52	M	TS; OC involvement
9	57	F	PS
10	58	F	TS
11	65	M	TS
12	72	F	PS

Table 1.

Demography and Preop radiological findings.

In neuroimaging, the tuberculum sella location was in seven cases, planum sphenoidale was in four cases, and the TS-PS region was in one case. All optic canal (OC) involvement and internal carotid artery (ICA) encasement cases arose from tuberculum sella meningioma (Figure 5).

Figure 5.

Radiological illustration of cases.

4.2 Resection status

Figure 6 shows the distribution resection status of the tumor. Complete resection of the tumor could be achieved in eight cases and incomplete resection in four cases (cases 2, 3, 4, and 8).

Figure 6.

Distribution of resection status.

Figure 7 illustrates the post-op complete resection status of the tumor.

Figure 7.

Radiological illustration of a case of a tuberculum-planum meningioma, preoperative (a and b) and postoperative (c and d).

4.3 Ophthalmological outcome

The outcome of visual disturbances revealed, that there was improvement of vision in six cases, constant vision in four cases, and deterioration of vision in two cases (Figures 8 and 9).

Figure 8.

Distribution of outcome of visual disturbances.

Figure 9.

Ophthalmological illustration, preoperative (a and b), and postoperative (c and d).

4.4 Post-op complications

The post of complications were nasal complications including encrustation, synechiae, and anosmia found in five cases, cerebrospinal fluid (CSF) leak in two cases, and tumor recurrence in two cases. There was Diabetes Insipidus (DI) in one case (Table 2).

Case no	Complications	Management
1	Nasal encrustation	Nasal wash
2	DI, Tumor recurrence	Transient DI resolved with vasopressin.; Tumor recurrence—stable with follow-up scan
3	Tumor recurrence	Revision surgery
4	CSF Rhinorrhoea, Anosmia	Conservative
5
6	Nasal encrustation	Nasal wash
7
8	Tumor recurrence	Follow up
9
10
11	Anosmia	Assurance
12	Nasal synechiae	Functional endoscopic sinus surgery

Table 2.

Distribution of post-op complications with case distribution.

5. Discussion

Tuberculum sella and planum sphenoidale meningiomas are challenging anterior skull base tumors due to their treacherous anatomical relationship with neurovascular and endocrine structures. These lesions give rise to an early visual pathology with relatively slow progression. They may remain undiagnosed for longer periods of time because tumour-related other symptoms are missing or are subtle [7]. Surgical removal by craniotomy may result in traction injury to the visual apparatus, hypothalamic structures and there may be trouble in skull base hemostasis. On the other hand, the endonasal route can avoid these technical issues by good visualization from the bottom with control of the skull base vascular supply of the tumor. In the study, Ottenhausen et al., have shown that patients treated through extended endoscopic approaches might benefit from better rates of complete surgical resection, and visual outcome with preservation of olfaction, less CSF leakage with visual improvement [8]. Both mastery of conventional operative techniques and thorough endoscopic skills are essential for consistent, effective, and safe surgical performance [9].

Although there is some limitation of the surgical corridor through the endoscopic endonasal transsphenoidal approach, the removal of the medial portion of the lesser wing and anterior clinoid process increase the exposure and surgical freedom of the expanded endonasal approach [10].

There are cases described in the literature of tuberculum sellae meningiomas misinterpreted as pituitary macroadenomas, but this was not the case in our study [11].

Out of twelve cases operated, six cases presented an improvement of the visual acuity while in four cases the visual acuity remained stable, overall, this resulted in a stabilization of the preoperative visual acuity in over 83.33% of the treated cases, a percentage that is in accordance with endoscopic resection presented in the literature [12, 13]. In our study, TS meningiomas encasing and displacing the optic apparatus had a poor visual outcome.

Complete resection of the tumor was achieved in 66.67% (12/8) of cases, which is well between the described 56–100% margins found in the literature [13]. Incomplete resection was found in those cases which extended into the optic canal and encasement of vascular structures.

CSF leak occurred in one case and was managed conservatively. The lower incidence may be due to multilayer closure with vascularized nasoseptal flap.

Nasal complication with anosmia was found in two cases due to extensive dissection of olfactory mucosa for better exposure.

Tumor recurrences occurred in two cases. We believe this is due to the relatively small number of patients included in the study.

6. Conclusion

This study concludes that endoscopic endonasal transsphenoidal resection of TS-PS meningiomas is feasible. This surgical option can provide good tumor clearance, visual improvement, and less complications. This small series does not reflect the standardization of this technique, so larger case series are recommended.

Conflicts of interest

There are no conflicts of interest.