The Transplanum Transtuberculum Approaches for Suprasellar and Sellar-Suprasellar Lesions: Avoidance of Cerebrospinal Fluid Leak and Lessons Learned

Peer-Review Reports

The Transplanum Transtuberculum Approaches for Suprasellar and Sellar-Suprasellar Lesions: Avoidance of Cerebrospinal Fluid Leak and Lessons Learned Lino Mascarenhas1, Yaron A. Moshel1, Fatema Bayad1, Oszkar Szentirmai1, Al Amin Salek1, Lewis Z. Leng1, Christoph P. Hofstetter1, Dimitris G. Placantonakis1, Apostolos J. Tsiouris4, Vijay K. Anand3, Theodore H. Schwartz1-3

Key words Craniopharyngioma - Endonasal transsphenoidal approach - Meningioma - Planum sphenoidale - Rathke cleft cyst - Skull base - Tuberculum sellae -

Abbreviations and Acronyms CSF: Cerebrospinal fluid GTR: Gross total resection MRI: Magnetic resonance imaging NTR: Near total resection

- OBJECTIVE:

To present a large series of patients and examine the learning curve of the endonasal endoscopic transplanum, transtuberculum approach for primarily suprasellar or sellar-suprasellar tumors.

- METHODS:

We identified 122 patients who underwent 126 surgeries using the transplanum, transtuberculum approach. Extent of resection was determined with volumetric analysis of magnetic resonance imagings. Results concerning vision, endocrine function, and complications were noted.

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Average tumor volume was 14 cm3. The most frequent pathologies were pituitary macroadenoma (51.6%), craniopharyngioma (20.6%), and meningioma (15.9%). A total of 73% patients presented with visual compromise. Rates of gross total resection (GTR) and near total resection for the group as a whole were 58.1% and 13.7%, and for the patients in whom GTR was intended (n [ 90), rates of GTR and near total resection were 77.5% and 12.5% for a total of 90%. Extent of resection in this group was 97.6%. Vision improved in 52.4% and deteriorated in 4.8%. Favorable endocrine outcome occurred in 63.5%. The cerebrospinal fluid leak rate was 3.1% for the series as a whole. It improved from 6.3% in the first half of the series to 0 in the second half. Leak rates varied with technique from 11% (fat graft only) to 4.2% (gasket seal only) to 1.8% (fat plus nasoseptal flap) to 0 (gasket plus nasoseptal flap). The rate of other complications was 14.3% in the first half of the series and 1.6% in the second half. There was one infection (0.8%).

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- CONCLUSIONS:

From the Departments of 1Neurosurgery, 2 Neurology and Neuroscience, 3Otolaryngology, 4 Radiology, Brain and Spine Center, Brain and Mind Research Institute, Weill Cornell Medical College, New York Presbyterian Hospital, New York, New York, USA To whom correspondence should be addressed: Theodore H. Schwartz, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2014). http://dx.doi.org/10.1016/j.wneu.2013.02.032 Journal homepage: www.WORLDNEUROSURGERY.org

- RESULTS:

INTRODUCTION

The endonasal endoscopic transtuberculum transplanum approach is a safe and effective minimal access approach to midline pathology in the suprasellar cistern.

Although the transsphenoidal approach to the ventral midline skull base was first proposed more than a century ago, the contemporary widespread use of the endoscope in transsphenoidal pituitary surgery has contributed to the development of extended endonasal approaches enabling exposure beyond the sella turcica to include pathology other than intrasellar pituitary tumors (8-10, 13, 33). Together with the incorporation of rigid endoscopes and stereotactic navigation systems into neurosurgical practice and an active collaboration between endoscopic sinus surgeons and neurosurgeons, extended endonasal endoscopic approaches have become accepted minimally invasive, or “minimal access,” routes to the midline and paramedian skull base and to the overlying subarachnoid space.

Several pioneering groups have published anatomic cadaver studies, small case series, and conceptual articles illustrating the possibilities with a purely endonasal endoscopic approach to remove a variety of lesions throughout the cranial base, third ventricle, and subarachnoid cisterns (2, 4, 6, 11, 12, 18, 21, 27, 29-32, 35-37, 39, 41, 51, 54, 55). In general, extended endonasal endoscopic approaches avoid the inherent risks of transcranial surgery, mainly related to brain retraction and manipulation of neurovascular structures that lie between the operative surgeon and the pathology. The endoscopic endonasal transplanum and transtuberculum approach to the suprasellar cistern is the most commonly

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performed of the extended endonasal approaches. The indications include not only large pituitary macroadenomas that extend high above the planum but also midline suprasellar craniopharyngiomas, Rathke cleft cysts, planum sphenoidale, and tuberculum sellae meningiomas, among other pathologies. This approach has been well-described and successfully implemented before the era of endonasal endoscopy using the microscope (10, 17). Nevertheless, criticisms still exist in the literature of the transsphenoidal transplanum approach, whether using the microscope or the endoscope, claiming that the rates of cerebrospinal fluid (CSF) leak are too high and the maneuverability too limited for general application within

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the neurosurgical community. However, as instruments and closure techniques have evolved, so have the results of surgery. With this in mind we reviewed our experience during 8 years in a large series of patients to discuss the indications, complications, limitations, and potential benefits of this approach and how improvements in instrumentation and surgical philosophy have impacted results. METHODS After approval by institutional review board, we retrospectively reviewed a prospectively collected database of all patients who underwent fully endoscopic endonasal skull base surgery performed by the two senior authors between April 2004 and March 2012. After each case, the operative surgeon indicated on a database which approach was used in removing the lesion. All patients in whom a transplanum and/or transtuberculum approach was used, either alone or in combination with a transsellar approach, were identified. We eliminated patients in whom the transplanum transtuberculum approach was part of a larger multicorridor approach. All cases involved lesions that were either primarily located or extended above the diaphragm sellae and required the arachnoid opened to gain access around the tumor with associated significant high-flow CSF leakage. Data were collected by retrospectively reviewing office and inpatient charts, preoperative and postoperative magnetic resonance imaging (MRI) studies, operative and pathologic reports. All complications including new neurological deficits, endocrine dysfunction, ophthalmologic status, hemorrhage, infarction, infection, CSF leak, as well as medical complications such as pneumonia, deep venous thrombosis, pulmonary embolus, and death were recorded. The postoperative extent of resection was determined using volumetric measurements comparing preoperative and postoperative contrast enhanced MRI examinations and was classified as gross total resection (GTR) of the imagingdefined abnormality, near total resection (NTR) (
95%), or subtotal (<95%) resection. The details of the transplanum transtuberculum approach are detailed

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elsewhere (5, 35, 41, 54). We will only highlight unique aspects of the surgery when performed at our center. Illustrative imaging findings (preoperative and postoperative) of pathologies that can be addressed using this approach are provided in Figure 1. Intraoperative pictures illustrating aspects of the surgical technique concerning resection of the pathology, reconstruction of the skull base, and important anatomic relationships are provided in Figures 2 and 3. A surgical team approach that included an otolaryngologist and a neurosurgeon is used for all extended endoscopic skull base cases. Procedures are routinely performed under general anesthesia and antibiotics, glucocorticoids, and antihistamines are administered. For pituitary tumors, we use cefazolin and for intradural, intraarachnoidal tumors, such as meningiomas and craniopharyngiomas, we use triple antibiotics. We administer intrathecal fluorescein (0.2 mL of 10% fluorescein is injected in 10 mL of CSF) to all our patients. For cases in which we perform a transplanum transtuberculum approach, this is usually performed through a lumbar drain, which is left open for 24 hours after surgery and drained at a rate of 5 mL/hr. In the beginning of our series we used lumbar drains less frequently and in this situation the fluorescein was administered through a lumbar puncture. The patient’s head is placed in a threepoint fixation, slightly elevated, in extension, and slightly turned to the right. Intraoperative neuronavigation is used for all procedures. The surgical procedure is performed as described in the literature, although we routinely preserve the middle turbinates unless turbinectomy was required for exposure. Posterior ethmoidectomies were performed until flush with the planum sphenoidale. A wide sphenoidotomy, including removal of the keel of the sphenoid is performed so the nasoseptal flap can lie flat on the floor of the sphenoid. The sphenoidal mucosa is completely stripped so a mucocele does not form behind the flap. Our closure techniques have changed and evolved over time, with some overlap between the periods they were used. We started by using fat within the sella, covered by an artificial tissue sealant, either Tisseel (Baxter, Deerfield, Illinois,

USA) in the earlier years or Duraseal (Covidien, Mansfield, Massachusetts, USA) starting in 2006. At a later time we adopted the gasket seal closure, which consisted of an overlay of fascia lata buttressed with a countersunk piece of Medpore (Porex, Newnan, Georgia, USA) (19, 42). This material can be cut with scissors to the precise shape of the skull base defect and is very maneuverable due to a handle it contains in its design that can be grasped with a forceps. The aim is to obtain a tight fit closure of the skull base. It is then covered with Duraseal (Covidien). As an alternative to the gasket seal, and considering the importance of vascularized autologous biological materials for prolonged sustainability of closure, we started using the nasoseptal flap (25) over the sellar fat graft, and this is kept in place with a final layer of Duraseal (Covidien). To maximize the closing potential and obtain the maximum benefit of both techniques, we ended up opting for the gasket seal covered with a nasoseptal flap, which is then held in place with Duraseal (Covidien). Rates of CFS leak were calculated for each of these closure techniques and for each pathology type. We also examined the learning curve by separating our series into a first half (n ¼ 63 cases) and a second half. We then fill the nasal cavity with Floseal (Baxter) for hemostasis. A small piece of Telfa is finally placed in each nostril overnight to absorb any drainage and is removed in 1e2 days. If a lumbar drain is placed intraoperatively, it typically drains at 5 mL/hr for 24 hours and is then removed in the evening on postoperative day 1. The patient will then lie flat during the night after its removal, decreasing the risk of a spinal headache when getting out of bed on postoperative day 2. RESULTS We identified 122 patients undergoing 126 surgeries who met inclusion criteria. They had undergone a transplanum and/or transtuberculum approach either in isolation or combined with a transsellar approach. The average age was 51.3 years (17.5 years) (range, 5e86 years) and there were 52 men. The average follow-up was 39 months (25.7 months) (range, 7e102 months).

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Figure 1. Representative preoperative and postoperative gadoliniumenhanced magnetic resonance imaging scans of cystic cranipharyngioma (A, B), tuberculum meningioma (C, D), residual suprasellar adenoma after prior microscope-based transsphenoidal surgery (E, F), suprasellar dermoid

Prior Treatments Of the 122 patients, 22 (18%) had previously undergone surgery consisting of prior transsphenoidal surgery (n ¼ 8), prior craniotomy (n ¼ 6), prior endonasal endoscopic surgery (n ¼ 3), prior transventricular surgery (n ¼ 3), and combined craniotomy and transsphenoidal surgery (n ¼ 2). Six of these patients had also been treated with radiation therapy. Three of the 122 patients had repeat surgery, one patient with two operations for a recurrent pituitary carcinoma, one elderly patient with repeat cystic fenestration of a recurrent craniophryngioma, and one for more complete resection of a subtotally resected chordoma. Preoperative symptoms are listed in Table 1—the three most common of which were visual complaints (including visual loss and/or diplopia) (73.81%), headache (28.56%), and endocrinopathy

(G, H), planum meningioma (I, J), residual suprasellar adenoma after prior microscope-based transsphenoidal surgery (K, L), macroadenoma (M, N), craniopharyngioma (note residual tumor attached to hypothalamus) (O, P).

(16.6%). The details of the preoperative visual findings are listed in Table 2 and the details of the preoperative endocrine findings are listed in Table 3. The range of histology encountered is listed in Table 4. Of note, the most common was pituitary adenoma (51.6%), followed by craniopharyngioma (20.6%) and meningioma (15.87%). Extent of Resection Analysis of postoperative contrast enhanced volumetric MRI scans could be performed on 124 surgeries. Rates of GTR and NTR for the group as a whole were 58.1% and 13.7%, and for the patients in whom GTR was intended (n ¼ 90), rates of GTR and NTR were 77.5% and 12.5% for a total of 90%. Extent of resection in this group was 97.6%. In patients in whom GTR was intended and not

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achieved, reasons were invasion and/or adhesion of the tumor to the hypothalamus (n ¼ 1), third ventricle (n ¼ 5), foramen of Monro (n ¼ 1), basilar artery (n ¼ 2), carotid artery (n ¼ 3), anterior communicating complex (n ¼ 4), cavernous sinus (n ¼ 3), optic nerves (n ¼ 2), chiasm (n ¼ 2), residual in posterior superior sella (n ¼ 5), inferior sella (n ¼ 1), and anterior superior sella (n ¼ 2). Thirty-six surgeries were intentionally subtotal. Indications for subtotal resection were craniopharyngiomas with hypothalamic invasion in pediatric patients, cyst fenestration in elderly patients, invasion into the lateral cavernous sinus, and brain invasion in elderly patients. Visual and Endocrine Outcome In the 93 patients with visual complaints preoperatively, vision was improved in 66

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Figure 2. Steps in resection of tuberculum meningioma shown in Figure 1C and D. (A) Mobilization of the tumor after internal decompression reveals pituitary stalk and optic chiasm. (B) Endoscopic removal of the diaphragm sella and last piece of tumor. (C) Image of decompressed stalk and chiasm with preserved perforators after resection. (D) Gasket seal closure of

surgeries (52.5%), unchanged in 54 (42.7%), and worse in 6 (4.8%). Patients who had visual deterioration included one patient with a new third nerve palsy who had normal vision preoperatively and five patients with tumors densely adherent to the optic apparatus who had visual complaints preoperatively. We defined favorable endocrine outcome as patients with normal preoperative function that was unchanged postoperatively, patients with preoperative hormone excess who became normal after surgery, and patients who required hormone supplementation before surgery and remain unchanged after surgery. Unfavorable outcomes include those in whom a patient with normal endocrine function developed an endocrine insufficiency, patients who required additional hormone supplementation after surgery, and patients with a hormonal pathologic excess that did not normalize during follow-up. Using these categories, there were favorable outcomes in 80 patients (63.5%),
2 pituitary axis deficits in 25 patients (19.8%), 1 pituitary axis deficit in 15 patients (11.9%), and persistent hormone excess in 6 patients (4.8%).

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defect using an onlay of fascia lata held in place with countersunk piece of Medpore. (E) Nasoseptal flap in place. (F) Duraseal holds the flap in place and creates a final watertight layer. Note that the Duraseal is placed using a 14-gauge angiocatheter passed through the tip of a ring curette to direct the flow of sealant.

Complications All patients had high flow intraoperative CSF leaks. There were four postoperative CSF leaks (3.1%). Eighteen patients were closed with a fat graft only and in this group there were two leaks (11%). After development of the gasket seal, there were 24 patients who had a gasket seal closure and in this group there was only one leak (4.2%). After introduction of the nasoseptal flap, there were a subsequent 55 patients closed with a fat graft covered by a nasoseptal flap. In this group there was only one leak (1.8%). In a subsequent 29 patients, a nasoseptal flap was added to the gasket seal closure and there were no leaks. The CSF leak rate associated with each technique is illustrated in Figure 4. With regards to pathology, the four leaks occurred in patients with meningioma (n ¼ 2) craniopharyngioma (n ¼ 1), and Rathke cleft cyst (n ¼ 1). A full list of complications is presented in Table 5. The Learning Curve All four CSF leaks occurred in the first half of our series (n ¼ 63 patients; 6.3%). In the second half of the series (n ¼ 63) there

were no leaks. As for other complications, the rate in the first half was 14.3% compared with 1.6% in the second half. Mortality was 3.1% in the first half and 0 in the second half. Nevertheless, there was no significant difference in the average volume of tumors in the first half (13.8 cm3) compared with the second half (14.6 cm3) and no significant change in the rate of GTR (60.3% in the first half compared with 55.7% in the second half). DISCUSSION The field of endoscopic endonasal skull base surgery has rapidly evolved because of technological innovations and the development of operative approaches by several innovative groups (2, 4, 6, 11, 18, 21, 27, 29-32, 35-37, 39, 41, 51, 54, 55). The endonasal transplanum transtuberculum approach, the most commonly performed of these approaches, extends the exposure beyond the sella by removing the tuberculum sella and a portion of the planum sphenoidale to enable surgical access within the suprasellar cistern. As with any new approach there is a learning curve that must be surmounted to achieve

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Figure 3. Intraoperative endoscopic views. (A) After resection of planum sphenoidale meningioma shows the A1, anterior communicating artery, and A2 branches free of tumor. The optic nerves have been decompressed of tumor out through the medial optic canals. Note the green fluoresceinstained cerebrospinal fluid seen through the intact lamina terminalis. (B) After esection of craniopharyngioma reveals the basilar tip, posterior communicating arteries, and third nerves bilaterally just above the superior cerebellar arteries. The intact pituitary stalk is identified on the left, with small remnants of tumor just below the optic chiasm and tracts. One of the mammillary bodies can be seen in the center of the image. (C) The view up

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toward the roof of the third ventricle after removing the large craniopharyngiomas. Note the residual tumor attached to the wall of the hypothalamus. (D) The same patient had hydrocephalus, and the dilated foramina of Monro, choroid plexus, and thinned fornices frame a view up into the lateral ventricles. (E) Suprasellar dermoid being removed from the medial optic nerve and recurrent artery of Heubner. (F) A2 branch passing over optic nerve. Indentation from removed tumor is visible under optic chiasm. Craniopharyngioma can be seen within the pituitary stalk before (G) and after (H) biopsy, performed to preserve pituitary function in preparation for radiation therapy.

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Table 1. Preoperative Symptoms Preoperative Symptom(s)

Number (%)

Visual complaints (isolated)

60 (47.62)

Visual complaints and headaches

18 (14.29)

Headaches (isolated)

8 (6.35)

Visual complaints and endocrine symptoms

7 (5.56)

Endocrine symptoms (isolated)

6 (4.76)

Incidental

5 (3.97)

Mental impairment (isolated)

5 (3.97)

Headaches and endocrine symptoms

4 (3.17)

Visual complaints, headaches, and endocrine symptoms

4 (3.17)

Visual complaints and mental impairment

3 (2.38)

Known previous tumor

3 (2.38)

Nasal fullness

1 (0.79)

Visual complaints, headaches, and mental impairment

1 (0.79)

Headaches and mental impairment

1 (0.79)

optimal results and continued evaluation of new ideas and technology must occur at periodic intervals as these results evolve (4, 20, 21). In this retrospective series we have demonstrated, as other investigators have previously, that suprasellar tumors can be safely removed using the endoscopic transplanum transtuberculum approach. In this large series of patients we report the evolution of low overall complication rates, and a negligible risk CSF leak rate with the adoption of new closure techniques. The low complication rates represent a substantial improvement compared with the high CSF leak rates that were reported early in the endoscopic skull base experience for suprasellar

tumors and lays to rest the criticisms of high CSF leak rates associated with this approach. The direct approach to ventrally located tumors afforded by endoscopic techniques overcomes the difficulties and blind spots of transcranial skull base approaches that expose the tumor from an anterolateral to medial trajectory and inevitably require brain retraction, manipulation of a compressed optic apparatus, and carotid artery, as well as its small perforating branches to gain access to a tumor. The incidence of new seizures after endonasal approaches to the suprasellar cistern (0) compares favorably with transcranial approaches to the same location

Table 2. Preoperative Visual Findings Preoperative Visual Findings

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Number (%)

Bitemporal hemianopsia

61 (48.41)

Unremarkable

33 (26.19)

Diminished bilateral visual acuity

12 (9.52)

Monocular visual field deficit

11 (8.73)

Diminished unilateral visual acuity

6 (4.76)

Homonymous hemianopsia

1 (0.79)

VI nerve palsy

1 (0.79)

III nerve palsy

1 (0.79)

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(5%e12%) (44, 57). In addition, the endonasal approach is particularly suited for visualizing and removing tumors extending into the medial optic canals, attached to the undersurface of the chiasm, and the medial walls of the third ventricle, and floor of the hypothalamus. Improved ventral exposure, however, is achieved at the expense of surgical access superior and lateral to the optic nerve and carotid artery, thereby substituting one set of exposure-related operative difficulties with another (12). Ultimately, the predominant tumor growth pattern and suprasellar/parasellar extension in relation to the optic nerves and carotid arteries dictates the optimal approach or combination of approaches. Appropriate patient selection with careful review of preoperative neurovascular imaging is critical to optimize outcome. In general, tumors with significant lateral extension beyond the carotid bifurcation or superolateral to the optic nerves are difficult to access through an endonasal approach. Most patients in this series presented with significant visual field loss. Perhaps the most important goal of surgery is cessation of any further visual loss and the restoration of any lost visual function. In the present series, postoperative ophthalmologic status was improved in most patients with preoperative deficits, and made worse in only a small fraction (6%). In comparison, visual decline has been reported in 10%e24% of patients after extended transcranial approaches to these lesions (14-16, 24, 46, 47, 50). Numerous factors are involved with visual outcomes after skull base tumor surgery including tumor type, degree of compression, duration of visual symptoms, thermal injury, and degree of intraoperative manipulation. The basal view afforded by the endoscopic approach allowed for early decompression, preservation of small subchiasmatic and optic tract perforators, and involves minimal manipulation of the compressed optic apparatus during tumor dissection. Suprasellar tumors could be maximally decompressed before the optic apparatus was manipulated and the attachment between the pathology and the nerves was visualized more clearly with the ventral approach. The ability to remove tumor within the optic canals and the use of angled endoscopes to inspect the optic canals is an important technical

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Table 3. Preoperative Endocrine Findings Preoperative Endocrine Findings

Number (%)

Unremarkable

73 (57.94)

Decreased TSH and/or thyroid hormones

9 (7.14)

Global anterior hypopituitarism

7 (5.56)

Other combinations of anterior hypopituitarism

7 (5.56)

Diabetes insipidus and partial or global anterior hypopituitarism

6 (4.76)

Decreased gonadotropins and/or sexual hormones

6 (4.76)

Elevated GH and /or IGF (acromegaly)

5 (3.97)

Elevated prolactin

4 (3.17)

Decreased ACTH

4 (3.17)

Decreased GH and/or IGF

3 (2.38)

Diabetes insipidus

2 (1.59)

TSH, thyroid-stimulating hormone; GH, growth hormone; IGF, insulin-like growth factor; ACTH, adrenocorticotropic hormone.

maneuver (1). Likewise, the ability to perform bimanual sharp dissection using bayoneted, rather than pistol-grip instruments has been facilitated with the development of endonasal bayoneted microinstrumentation. Another criticism of the endonasal approach has been the contention that the limited view leads to subtotal resection of the tumor. We achieved an average of 97.6% resection in patients in whom GTR was the goal. This included resection of meningiomas invading into the medial optic canals, which we have shown to be

accessible with an endonasal approach (1). These results are comparable to those achievable with craniotomy in similarly sized tumors. Factors that prevented complete resection included tumor components that were tightly adherent to the carotid artery or that encased the anterior communicating artery and its perforators. Tumor tissue that invaded the walls of the third ventricle was also not aggressively pursued. Finally, tumor tissue that was located within the cavernous sinus lateral to the carotid artery was also not aggressively pursued. Although

Table 4. Histopathology Results Histopathology Results

Number (%)

Pituitary adenoma

65 (51.59)

Craniopharyngioma

26 (20.63)

Meningioma

20 (15.87)

Rathke’s cyst

5 (3.97)

Other benign cysts

2 (1.59)

Chordoma

2 (1.59)

Epidermoid

1 (0.79)

Lymphoma

1 (0.79)

Metastasis

1 (0.79)

Cavernous malformation

1 (0.79)

Germinoma

1 (0.79)

Low grade chondrosarcoma

1 (0.79)

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maximal resection should ideally be the goal in all surgeries, patient age, functional status, medical comorbidities, and neurologically risky tumor extensions moderated the surgical goals to a maximal safe subtotal resection that allowed decompression of critical structures. In particular, elderly patients with giant craniopharyngiomas sometimes underwent decompression followed by radiation therapy and children with craniopharyngiomas invading the walls of the third ventricle also occasionally underwent subtotal resection followed by radiation (45, 48, 49, 52). A high rate of CSF leak has been another central criticism of the endonasal endoscopic approach. Early in the endonasal experience CSF leak rates of 10%e 40% were reported (18, 21, 56). Significant progress was made, however, with the introduction of the gasket seal and vascularized nasoseptal flap combined with the use of dural sealants and sellar reconstruction or placement of a Foley balloon in the nasal cavity to buttress the closure (7, 20, 25, 34, 42). In the present article we have also documented our learning curve, which evolved from an initial 6.3% leak rate down to 0 during progressive technical modifications. This evolution emphasizes the point that new techniques should be periodically reevaluated as they evolve and should not be prematurely dismissed as they may take 5e10 years to reach maturity. Similar evolution has been witnessed in the development of correct dosing in radiosurgery and proper coiling techniques for aneurysm obliteration (3, 22, 23, 28, 40). It is important to emphasize that it is critical that these closures be performed meticulously. If the gasket seal is not adequately leveraged or the nasoseptal flap does not completely cover the defect or pulls away from the skull base, or the patient has hydrocephalus, the closure may still fail in spite of these methods. Our experience is not unique and other centers also have reported leak rates w5% (26, 38, 43), which render the issue of CSF leak an historic problem. One of the perplexing features of endonasal cranial base approaches is the logic of operating through an unsterile corridor into a sterile environment. One would expect that endonasal intradural surgery would lead to a high rate of

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ably low and similar to that with transcranial surgery. CONCLUSION

Figure 4. Learning curve for skull base closure. The rate of postoperative cerebrospinal fluid (CSF) leak declined over time as we modified our closure technique. NS, nasoseptal.

postoperative meningitis or abscess formation, particularly around an intradural fat graft. However, we report a 0.8% incidence of infection. It is unclear why the infection rate is so low, but this has been consistent among other series of endonasal surgeries performed at other institutions (6, 11, 20, 21). Transcranial approaches to the ventral skull base carry

a risk of infection of 3.5% (14-16, 53). In our experience with endonasal surgery in other locations, meningitis has occurred in the setting of a postoperative CSF leak but in the absence of a leak, it is extremely uncommon. In summary, once a CSF leak rate of <5% can be achieved in a particular center, the rate of infection for endonasal surgery is accept-

Table 5. Complications Complications

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Number (%)

Cerebrospinal fluid leak

4 (3.1)

Carotid tear

1 (0.79)

Surgical site hematoma requiring reoperation

1 (0.79)

Deep venous thrombosis

1 (0.79)

Postoperative epistaxis

1 (0.79)

Postoperative surgical site infection complicated with stroke

1 (0.79)

Aspiration pneumonia

1 (0.79)

Chronic subdural hematoma

1 (0.79)

Stroke

1 (0.79)

Sinonasal infection

1 (0.79)

Hydrocephalus

1 (0.79)

Death in the context of dilated cardiomyopathy

1 (0.79)

Death after complicated cerebrospinal fluid leak

1 (0.79)

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We report on the evolution of the extended endonasal transtuberculum transplanum approach for resection of suprasellar tumors in a large series of patients. The approach enables a ventral trajectory for the resection of midline tumors that compress the optic apparatus and even extend into the ventricular system, either prechiasmatic or postchiasmatic, with minimal manipulation of neurovascular structures and early identification of perforating vessels. Combined with early decompression of the optic nerves, good visual outcomes are generally possible with a high extent of tumor resection. Alternatively, tumor debulking and cyst decompression can be performed with minimal morbidity if clinically indicated. Advances in skull base reconstruction and microsurgical instruments have reduced the complication rates to the point where the incidence of CSF leak are comparable to transcranial approaches and the risk of brain trauma, edema, and seizures is reduced. Limitations to the approach include significant tumor extension lateral to the optic nerves and to the carotid artery. REFERENCES 1. Attia M, Kandasamy J, Jakimovski D, Bedrosian J, Alimi M, Lee DL, Anand VK, Schwartz TH: The importance and timing of optic canal exploration and decompression during endoscopic endonasal resection of tuberculum sella and planum sphenoidale meningiomas. Neurosurgery 71(1 Suppl Operative):58-67, 2012. 2. Aydin S, Cavallo LM, Messina A, Dal Fabbro M, Cappabianca P, Barlas O, de Divitiis E: The endoscopic endonasal trans-sphenoidal approach to the sellar and suprasellar area. Anatomic study. J Neurosurg Sci 51:129-138, 2007. 3. Benedict SH, Bova FJ, Clark B, Goetsch SJ, Hinson WH, Leavitt DD, Schlesinger DJ, Yenice KM: Anniversary paper: the role of medical physicists in developing stereotactic radiosurgery. Med Physics 35:4262-4277, 2008. 4. Cappabianca P, Cavallo LM, Colao A, del Basso de Caro M, Esposito F, Cirillo S, Lombardi G, de Divitiis E: Endoscopic endonasal transsphenoidal approach: outcome analysis of 100 consecutive procedures. Minim Invas Neurosurg 45:193-200, 2002. 5. Cappabianca P, Cavallo LM, Esposito F, de Divitiis O, Messina A, de Divitiis E: Extended

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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Citation: World Neurosurg. (2014). http://dx.doi.org/10.1016/j.wneu.2013.02.032

55. Schwartz TH, Fraser JF, Brown S, Tabaee A, Kacker A, Anand VK: Endoscopic cranial base surgery: classification of operative approaches.

Received 5 December 2012; accepted 5 February 2013

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