parasellar lesions.

Peer-Review Reports

Endoscopic Endonasal Surgery for Nonadenomatous Sellar/Parasellar Lesions Garni Barkhoudarian1, Gabriel Zada2, Edward R. Laws3

Key words Craniopharyngioma - Endoscopy - Pituitary - Rathke cleft cyst - Transphenoidal surgery -

Abbreviations and Acronyms CSF: Cerebrospinal fluid CT: Computerized tomography DI: Diabetes insipidus MRI: Magnetic resonance imaging NGGCT: Nongerminomatous germ cell tumor SCC: Squamous cell carcinoma From the 1Department of Neuroscience and Neurosurgery, Brain Tumor Center and Pituitary Disorders Program, John Wayne Cancer Institute, Santa 2 Monica; Department of Neurosurgery and University of Southern California Pituitary Center, Neuro-Oncology and Endoscopic Pituitary/Skull Base Program, Keck School of Medicine of University of Southern California, Los Angeles, California; and 3Department of Neurosurgery, Harvard University, Brigham and Women’s Hospital, Boston, Massachusetts, USA To whom correspondence should be addressed: Edward R. Laws, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2014) 82, 6S:S138-S146. http://dx.doi.org/10.1016/j.wneu.2014.07.017 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2014 Elsevier Inc. All rights reserved.

INTRODUCTION The concept of the minimally invasive transnasal approach to the anterior skull base was initially conceived for pituitary adenomas, the most common intrasellar pathology. Because the operating endoscope became a critical and essential feature of this approach, the ability to move beyond strictly sellar pathology became obvious. The extended transsphenoidal approach, initially pioneered with the operating microscope, became increasingly versatile as the operating endoscope enhanced the capabilities of this exciting technical advance. Because this approach evolved, it was rapidly applied to a wider spectrum of pathology. Concurrently, our colleagues in head and neck surgery became less insistent on the enbloc removal of some midface lesions, as

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- INTRODUCTION:

This article demonstrates the experience with endoscopic transphenoidal anterior skull base surgery for lesions other than pituitary adenomas. The spectrum of lesions, results, and complications are presented.

- PATIENTS

AND METHODS: This series includes patients with 102 lesions other than pituitary adenomas operated upon using the endoscopic approach. The results and complications were reviewed retrospectively.

The most common lesions treated were Rathke Cleft Cysts (n [ 39) and craniopharyngiomas (n [ 18) in a total of 82 tumors. There were 8 patients with inflammatory lesions, and the remainder had a variety of unusual pathologies. Complications other than diabetes insipidus (n [ 12) were uncommon, with 6 postoperative cerebrospinal fluid leaks.

- RESULTS:

- CONCLUSIONS:

The endoscopic anterior skull base approach is highly effective in treating a large variety of lesions other than pituitary adenomas. The adoption of the nasoseptal flap for closure has markedly reduced the incidence of spinal fluid leaks, and is used routinely for lesions that violate the intracranial compartment.

follow-up data did not always support this concept. Pure endoscopic and endoscopic-assisted transsphenoidal surgery rapidly emerged in the late 1990s and early 2000s, as the obvious benefits of this technology, including improved panoramic visualization, illumination, angled lenses, and increased mobility, became obvious to surgeons. Because lesions of the anterior skull base, the suprasellar compartment, the clivus, and all of the anterior sinuses became accessible using this minimally invasive transnasal endoscopic method, its popularity has spread quite widely during the past decade. The collaboration between neurosurgeons and otorhinolaryngologists has been essential to the development and spread of this approach, and to its application to a variety of pathologic entities. Also essential to this novel approach is the surgeon’s adherence to the basic principles of skull-base surgery. Paramount among these is the incorporation of the basic aspects of microsurgery and microtechnique combined with minimizing brain retraction. These appoaches require surgery to be performed with two hands, thus dividing the operation between the microsurgeon,

and the surgeon responsible for maintaining visualization and illumination with the endoscope. This team approach contributes greatly to the elegance of the operative procedure. The aim of this study was to review our institutional experience with nonadenomatous lesions of the sellar and parasellar region, particularly with respect to the endonasal endoscopic approach as our preferred operative technique for treating these lesions. ENDOSCOPIC EXPERIENCE Our experience, at present, at the Brigham and Women’s Hospital (April 2008eOctober 2011) includes 438 operations with the endonasal transsphenoidal approach. Of these, the endoscope was used on its own (97.5%) or in concert with the operative microscope in 408 patients. Typically, the microscopic approach alone was reserved for emergency operations, those without surgical assistants experienced with endoscopy, and for the education of residents unfamiliar with the microscopic approach. Of these 408 operations, 102 (25%) were for parasellar pathology other than pituitary

WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.07.017

PEER-REVIEW REPORTS GARNI BARKHOUDARIAN ET AL.

NONADENOMATOUS LESIONS

Table 1. Complications Encountered Complications

Number of Patients

%

DI (permanent)

12

11.76

DI (transient)

3

2.94

SIADH

9

8.82

Epistaxis

6

5.88

CSF leak

6

5.88

Visual loss

2

1.96

Meningitis

2

1.96

Hypopituitarism

2

1.96

Vascular injury

1

0.98

Pneumonia

1

0.98

Tumor bed hemorrhage

1

0.98

Table 2. Pathology Encountered Number of Patients Tumors/Cysts

DI, diabetes insipidus; SIADH, syndrome of inappropriate antidiuretic hormone; CSF, cerebrospinal fluid.

adenoma (Table 1). There was a wide range of disorders—the most common being Rathke cleft cysts, craniopharyngiomas, and arachnoid cysts. In our experience, the endonasal transsphenoidal approach was the most versatile for these lesions. Use of the endoscope, including angled lenses, offered better visualization and more definitive treatment of these lesions. The most common presenting symptom of these lesions was headaches, followed by visual loss and hypopituitarism. A small number of tumors were identified incidentally, particularly with regard to cystic lesions such as Rathke cleft and colloid cysts. Of those patients presenting with headaches, most were improved or remained the same. Only 1 patient, who had undergone pituitary biopsy for Wegener’s granulomatosis, had worsening of her headaches (Table 1). In patients who had presented with visual field or acuity deficits, most had improved or unchanged postoperative visual examinations. Three patients, all of whom harbored craniopharyngiomas, had worse postoperative visual examinations, 2 of which were probably related to vascular insufficiency. Some postoperative improvement occurred in all 3, none of whom was blind. The overall complication rate, including anterior and posterior pituitary dysfunction, was 38.2%. Craniopharyngioma had the highest aggregate (including major, minor, and hormonal) complication rate

Rathke cleft cyst

39

Craniopharyngioma

18

Arachnoid cyst

8

Pituitary cyst

2

Colloid cyst

1

Chordoma

3

Chondrosarcoma

1

Granular cell tumor

1

Metastases

4

Lymphoma

1

Meningioma

1

Pituitary carcinoma

1

Oncocytoma

2

Total tumors/cysts

82

One RCC associated with GH secreting adenoma

Breast CA, prostate CA, renal cell CA, SCC

Inflammatory Disease Lymphocytic hypophysitis

4

Wegener’s granulomatosis

1

Giant repairative granuloma

1

Granulomatous lesion

1

Pituitary inflammation

1

Total Inflammatory Disease

8

Bone Lesions Fibrous dysplasia

1

Basilar invagination

1

Lipomatous bone cyst

1

Total Bone Lesions

3

Miscellaneous Nondiagnostic

3

Patients presented with headaches and enlarged pituitary glands

Normal gland

2

Work-up for Cushing’s disease

Spontaneous CSF Leak

2

Pituitary hyperplasia

1

Aneurysm

1

Total Miscellaneous Total Nonadenomatous lesions

1 102

RCC, Rathke cleft cyst; GH, growth hormone; CA, carcinoma; SCC, squamous cell carcinoma; CSF, cerebrospinal fluid.

of 61%, followed by Rathke cleft cysts at 38.5% and arachnoid cysts at 25% (Table 2). The most common nonhormonal complications were postoperative

WORLD NEUROSURGERY 82 [6S]: S138-S146, DECEMBER 2014

epistaxis (6%) and cerebrospinal fluid (CSF) leak (5%). Although approached from similar surgical avenues (some are transsphenoidal-

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transsellar and others are transtuberculum or transclival), each of these lesions has somewhat different nuances of intraoperative and postoperative care. Key topics with diagnostic and operative challenges are discussed. The application of endoscopy is evaluated for each of these diagnoses.

RATHKE CLEFT CYST Rathke cleft cysts are one of the most common nonadenomatous symptomatic lesions affecting the pituitary gland (69). The pathophysiology of these cysts is thought to be due to an abnormally enlarged Rathke pouch between the pars distalis and the pars intermedia within the pituitary gland (29). They can occur at the superior aspect of the gland and may extend into the suprasellar compartment. These lesions are most commonly associated with headaches (70%e85%), typically frontal or retro-orbital in location. Hypopituitarism can also occur, although more frequent in children (73). Although postoperative pituitary dysfunction is typically transient, preoperative endocrine deficits, especially diabetes insipidus (DI), frequently do not improve (16). Classic, these cystic lesions have been successfully treated by the microscopic transsphenoidal approach. Recent reports have demonstrated that the endoscopic transsphenoidal approach is a viable alternative. The endoscope offers the advantage of close inspection of the cyst wall to ensure its adequate removal without damage to the infundibulum or the posterior pituitary gland. Although complete cyst excision has been associated with an increased incidence of DI, recurrence rates are higher with incomplete cyst fenestration (34). Hence, detailed endoscopic visualization of the cyst wall and normal pituitary structures may improve surgical outcomes. Although occasionally used, instilling caustic agents, such as ethanol or hydrogen peroxide, does not decrease the recurrence rate of these cysts (3, 46). We recommend a vertical incision in the normal pituitary for exposure, and wide fenestration and complete evacuation of the cyst contents. If there is no intraoperative CSF leak we do not use a fat graft or reconstruct the floor of the sella, giving the cyst a path of least resistance into the sphenoid if it recurs.

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Figure 1. Magnetic resonance imaging (MRI) studies of arachnoid cyst (A and B), and Rathke cleft cyst (C and D).

ARACHNOID CYSTS Enclosed cystic lesions containing CSF can occur in the sellar and parasellar region. Most commonly, they are congenital and/or developmental arachnoid cysts. The pathophysiology is variable, but an incompetent diaphragma sellae with exvagination of the arachnoid into the sella is one possible mechanism. Preoperative imaging demonstrates a cyst with signal characteristics similar to CSF (hyperintense on T2, hypointense on T1, no diffusion restriction on diffusion weighted imaging). Contrast enhancement can be seen, but is typically a stretched, normal pituitary gland. These lesions can occasionally be associated with other pathology such as pituitary adenomas (61) (Figure 1).

Intraoperative findings demonstrate clear liquid cyst contents with a consistency similar to CSF. This fluid can occasionally be xanthrochromic. Meticulous inspection of the arachnoid membrane can often identify the point of communication with the subarachnoid space. By definition, an occult CSF leak should be assumed in these patients. This should be addressed with an autologous fat graft or other secure repair methods. Although these cysts have a longer recurrence-free period compared with Rathke cleft cyst and craniopharyngioma, they still can recur in up to 20% of patients, necessitating long-term follow-up with neuroimaging (64).




definition limited by a certain degree of selection bias (36). Endoscopy offered improved visual outcomes but was associated with increased pituitary dysfunction including DI. Inherent to the transsphenoidal approach was an increased incidence of CSF leaks (9%e18%). Conversely, inherent to the transcranial approach was an increased rate of postoperative seizures (8.5%). MENINGIOMA

Figure 2. Computed tomography (CT) angiogram, coronal and axial views, demonstrating a craniopharyngioma and its relationship to the carotid arteries as they enter the intracranial compartment.

CRANIOPHARYNGIOMA Although the pathogenesis of these lesions are likely somewhat related to Rathke cleft cysts, with various cell types trapped within Rathke’s pouch, craniopharyngiomas tend to behave in a more aggressive manner (76). These lesions frequently present with visual field deficits, pituitary dysfunction, and headaches. Other symptoms of tumor mass effect, such as nausea, vomiting, and the presence of hydrocephalus, can also be present. The diagnosis of craniopharyngiomas can be challenging, as they can mimic Rathke cleft cysts, cystic pituitary adenomas, or intratumoral hemorrhage on magnetic resonance imaging (MRI). Computerized tomography (CT) imaging can frequently demonstrate calcifications within the lesion, which can be pathognomonic. If craniopharyngioma is suspected, CT imaging is necessary not only for confirming the diagnosis, but also to identify the details of surrounding bony and vascular anatomy—the latter best seen with CT angiography (Figure 2). Definitive treatment of these lesions is gross total resection, with fractionated radiotherapy, radiosurgery, or proton beam therapy sometimes used as useful adjuncts. Given that craniopharyngiomas can present in various locations (e.g., intrasellar, suprasellar, intraventricular, or a combination), a variety of surgical approaches can be used for resection (41, 57). The ideal craniopharyngioma approached by the transsphenoidal route has its epicenter in or near the sella turcica.

They most commonly arise from the infundibulum. Accordingly, the tumors are frequently retrochiasmal in relation to the optic apparatus. The surgical transsphenoidal vector is ideal for intraventricular and posterior fossa extension. For these lesions, it is pertinent, after emptying accessible cystic portions and safely debulking solid components, to resect the tumor capsule using extracapsular dissection with the extended endoscopic transsphenoidal approach. Because of the large bony and dural defect, a pedicled nasoseptal flap and use of fascia and fat in a multilayered closure can help decrease postoperative CSF leaks (8). The adherent nature of the capsule of craniopharyngiomas to surrounding neurovascular structures makes 2-handed microdissection techniques performed under optimized visualization critical (70). Comparing microscopic and endoscopic approaches, there does appear to be a difference in clinical outcomes with each technique (9, 49, 71). Lesions located predominantly within the sella have a higher likelihood of gross total resection with the endoscopic endonasal approach (25, 26). In such cases, where the sella is enlarged, the diaphragm usually acts as a barrier that prevents direct involvement of and adhesions to the optic apparatus and the hypothalamus. Meta-analysis of the literature demonstrates that craniopharyngiomas that were resected with the transsphenoidal approach had better outcomes regarding gross total resection, although these studies are by


Meningiomas removed with the endonasal endoscopic approach are typically those arising from the tuberculum sella, planum sphenoidale, and olfactory groove. The advantages of the endonasal endoscopic approach are multifold, including minimal brain retraction and early obliteration of the dural blood supply. Disadvantages include a narrow working environment, suboptimal visualization of critical cerebral vasculature, and dural defect closure complicated by postoperative CSF leakage. As one should evaluate any surgical approach, these advantages and disadvantages should be weighed and applied to the patient’s best interest, as compared with standard craniotomy techniques, which also offer excellent rates of tumor resection and clinical outcomes in the hands of experienced surgeons (24, 42). The ideal meningioma for the endoscopic endonasal approach is one centered in the posterior frontal fossa with a higher craniocaudal to anterior-posterior ratio. Meningiomas with significant dural extensions, lateral growth beyond the plane of the carotid arteries and cranial nerves, or calcifications are less suitable for this approach. Although the ultimate goal for typical meningioma resection is a Simpson grade I result, this is difficult to achieve for most tumors using the endonasal approach (65). Hence, these patients need to be observed closely postoperatively with frequent MRI studies. Reoperation or radiosurgery for recurrence should be considered at an early stage. Optimal exposure for skull base meningiomas treated by endoscopic approaches is achieved with adequate drilling of the skull base and wide dural exposure. By necessity, planning for skull base reconstruction typically involves autologous graft harvesting and frequently, rotation of a pedicled nasoseptal flap (14) (Figure 3).


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alternative where proton beam centers are unavailable (21, 23, 55) (Figure 4).

METASTASES

Figure 3. Meningioma of the tuberculum sellae. (A) Sagittal magnetic resonance imaging (MRI) with contrast; (B and C) intraoperative views before and after removal from the optic chiasm and carotid artery.

CHORDOMA/CHONDROSARCOMA Chordomas are thought to be benign tumors that originate from notochord remnants along the skull base and spinal column. One of the more common sites from which these tumors originate is at the occipitosphenoidal suture of the clivus (11, 22). Hence, the endonasal transsphenoidal approach offers a direct reach to these typically midline lesions (40). Histologic evaluation with special stains identifies some of these lesions as low grade chondrosarcomas; others have been classified as the chondroid variant of chordoma. Strictly speaking, chordomas are benign tumors, but can behave quite aggressively. An almost undetectable residual has the potential for disastrous recurrence. Hence, the goal of gross total resection is critical to a favorable outcome. The endoscopic endonasal approach offers the theoretic advantage of superior visualization (27). Although 5- and 10-year follow-up data are not yet available, early data suggest that this approach is comparable to the microscopic endonasal technique with similar, if not lower, complication rates (67). The pedicled nasoseptal flap closure of the dural defect, when present, can help decrease postoperative CSF leakage (32). Chordomas and chondrosarcomas arise from the skull base and often maintain their extradural nature, making extradural approaches such as the transsphenoidaltransclival approach optimal for their treatment. In some cases, however, the

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tumor will invade the dura of the posterior fossa and can be adherent to the vertebrobasilar complex or cranial nerves, making gross total resection much less feasible. In either case, careful microdissection and skull base repair principles are required to safely and effectively treat these patients. Given the high rate of recurrence, which can occur years after surgical resection, it is important to follow these patients closely with frequent neuroimaging. Reresection, when safe and feasible, is the ideal treatment for tumor recurrence. Proton beam radiation is ideal for surgically inaccessible tumor remnants with stereotactic fractionated radiotherapy an

The pituitary gland is a relatively frequent site of distant metastases for numerous carcinomas. This is likely due to its rich vascular supply and its double capillary bed incorporated into the pituitary portal system. Common cancers metastatic to the pituitary region include breast, lung, prostate, and renal cell carcinoma (54). The most common finding for symptomatic pituitary metastases is pituitary dysfunction, particularly DI (70%e100%) (52). Anterior pituitary dysfunction is often seen, but to a lesser extent. Other presenting symptoms are those of tumor mass effect such as visual field deficits and cranial nerve defects. Headaches are often reported. Comprehensive management of these lesions often requires multidisciplinary involvement, given that these tumors are surgically incurable. The primary goals are to decrease mass effect and obtain tissue diagnosis for tumor staging (when necessary). It is important to note that pituitary adenomas are common lesions, occurring in 10%e20% of the general population (69). They can be hypermetabolic on positron emission tomography imaging and can mimic metastatic disease (6, 35, 37). Hence, isolated pituitary lesions in the setting of a primary carcinoma should warrant a surgical biopsy before more aggressive chemotherapy and radiation therapy regimens. We have encountered rare cases of

Figure 4. Chordoma of the clivus. Sagittal and axial magnetic resonance images (MRIs).




Figure 5. Metastatic cancer to the sella. (A) Axial computed tomography (CT) scan. (B) Positron emission tomography (PET) scan for 2-deoxyglucose showing strong activity in the sella.

cancers metastatic to a previously undiagnosed pituitary adenoma (Figure 5). Although surgical debulking of the tumor offers improvement in quality of life factors, such as visual loss and pituitary dysfunction, the overall survival for these lesions remains at 6e7 months. This is primarily due to the systemic tumor burden from the primary carcinoma and the late stage of the disease process (54, 66). Metastatic tumors to the pituitary region are often highly invasive and vascular, warranting added caution on the part of the surgeon. Squamous cell carcinoma (SCC) can occur in the parasellar region by perineural spread, rather than the more common hematogenous or lymphatic avenues. This occurs most commonly by the trigeminal nerve branches traversing the cavernous sinus. Presenting symptoms can often be trigeminal anesthesia or hypesthesia. Oculomotor dysfunction can be a later finding. Primary intracranial SCC has also been reported without a known primary source (45). Given the invasive characteristics of SCC, they are typically surgically incurable. Surgical biopsy by the endoscopic endonasal approach can help secure the diagnosis and stage the disease (17). LYMPHOMA Lymphoma of the pituitary gland is a rare but reported entity. Pituitary involvement

has been noted in both hematogenous lymphoma and primary central nervous system lymphoma. In an autopsy review, 23% of 165 patients with hematologic malignancies had hypophyseal lymphoma. Approximately 25% of a series of 22 patients with primary central nervous system lymphoma also had pituitary involvement (18). Similar to other metastatic disease, these patients often had posterior pituitary dysfunction and, to a lesser extent, anterior pituitary dysfunction, visual field deficits, and cranial nerve deficits. Endoscopic surgical biopsy of these lesions has been reported in selected patients (39, 51). The biopsy secured the initial diagnosis of pituitary lymphoma, allowing for systemic treatment of the disease. GERM CELL TUMORS Germ cell tumors are uncommon lesions that can involve midline intracranial structures, most commonly in the suprasellar and pineal regions (15, 68). There are various types including germinomas, yolksac tumors, embryonal cell tumors, teratomas, and mixed subtypes. They are commonly categorized into germinomas and nongerminomatous germ cell tumors (NGGCTs). Typically, suprasellar germinomas present first with DI, and subsequently may produce visual loss and


hypopituitarism. They occur most frequently in young men. These lesions typically enhance homogenously on MRI and can involve the pituitary stalk, hypothalamus, and other suprasellar structures (43). Pure germinomas are extremely radiosensitive, differentiating themselves from NGGCTs. Hence, the diagnosis of these lesions can result in varying clinical interventions. When suspecting a suprasellar germinoma, it is important to inspect the imaging studies of the pineal gland, the ventricular system, and the entire floor of the third ventricle from the pineal to the tuber cinereum for enhancing lesions. Serum and CSF assays for b-human chorionic gonadotropin and a-feto-protein can help differentiate germinomas from NGGCTs. In the setting of equivocal diagnostic tests, surgical biopsy may be warranted. It is important to note that surgical resection of germ cell tumors is not often curative, whereas effective radiation and/or chemotherapy treatment for germinomatous germ cell tumors may be more effective in achieving disease control (60). Surgical treatment may be indicated for the resection of teratomatous components after adjuvant treatment. DERMOID AND EPIDERMOID CYSTS Although rare entities in the parasellar region, dermoid and epidermoid cysts have been reported (20, 50). Dermoid cysts are typically midline lesions that can occur intracranially, occasionally in the parasellar region. Imaging characteristics are similar to craniopharyngiomas, with high protein content resulting in T1 signal shortening. Epidermoid cysts are more typically found lateral to midline—the cerebellopontine angle being one of the more common locations. These appear cystic on routine CT scans and MRI with bright T1 and T2 signals. However, diffusion weighted imaging typically shows restricted diffusion (bright signal) in these lesions, differentiating them from arachnoid or other neuroepithelial cysts (62, 72). If there is suspicion of these lesions on routine imaging, the appropriate sequences should be obtained before surgical intervention. The endoscope provides an excellent visualization tool for the treatment of epidermoid tumors, as these lesions often grow through the cisternal spaces and are attached to many neurovascular structures.


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Figure 6. Suprasellar epidermoid tumor e sagittal and coronal magnetic resonance images (MRIs).

The ability to use angled endoscopic lenses to look around surgical corners, either with pure endoscopic or endoscopic-assisted operations, is extremely useful in demonstrating residual tumor and maximizing tumor resection. Fortunately, epidermoid tumors can often be grossly debulked using mechanical curettage and suction, and it is often necessary to leave the tumor capsule behind to avoid traction on critical structures (Figure 6). ESTHESIONEUROBLASTOMA Esthesioneuroblastoma is an uncommon entity, arising from the olfactory neuroepithelium in the nasopharynx. For lesions isolated to the nasal cavities (Kadish A stage), endoscopic endonasal resection has been reported (7). However, these tumors can invade the frontal skull base with intracranial extension (Kadish C stage) (56). En-bloc resection of these lesions is the gold standard for their surgical management, achieved with combined craniotomy and endonasal approaches. Because these lesions are aggressive in nature, chemotherapy and radiation have become a mainstay for the treatment of these lesions (47). Although there is some controversy for such an aggressive treatment regimen in Kadish A stages, there is a consensus for multimodality therapy in patients with Kadish B and C stages.

This disorder is typically characterized with peripartum anterior pituitary dysfunction, visual loss, and lymphocytic infiltration of the adenohypophysis. Lymphocytic hypophysitis can also occur in the setting of paraneoplastic disease associated with cancer. If DI is present, then the diagnosis of lymphocytic neurohypophysitis is more appropriate (58). Imaging characteristics are quite striking, with typically an enlarged and homogenously enhancing pituitary gland (1). Surgical management of this lesion is primarily diagnostic, although some benefit exists in decompressing and debulking the gland in the setting of visual loss or severe headaches (28, 30) (Figure 7). Once the diagnosis of lymphocytic hypophysitis has been established, either clinically or with surgical biopsy, the treatment of choice is corticosteroid therapy. Typically, first-line therapy consists of prednisone or methylprednisolone, 20e40 mg/ day for 2 weeks to 3 months (38, 75). During transsphenoidal biopsy, endoscopy can be useful to identify critical structures, including the infundibulum.

INFLAMMATORY CONDITIONS The pituitary gland can be affected by a number of inflammatory conditions. The most common is lymphocytic hypophysitis.

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Figure 7. Lymphocytic hypophysitis e sagittal magnetic resonance imaging (MRI).

Other inflammatory lesions in this region include the spectrum of granulomatous pituitary disease, such as sarcoidosis, idiopathic giant cell granulomatous hypophysitis, and chronic granulomatous disease (13, 63). These typically involve the entire pituitary gland, particularly the infundibulum, can present with DI and anterior pituitary dysfunction, and can cause local mass effect. Work-up of these lesions should include the search for systemic disease involvement and occult tuberculosis infections. Endoscopic biopsy of these lesions can help secure the diagnosis (2, 5). Wegener’s granulomatosis and Langerhans cell histiocytosis can also affect the hypophyseal region. BONY LESIONS The endoscopic endonasal approach has been reported for the management of various bony disorders causing compression of neural structures. The most common such lesions include fibrous dysplasia and basilar invagination. Fibrous dysplasia is a rare condition, occasionally associated with McCuneAlbright syndrome, typically involving bones of the skull base such as the sphenoid bone. Typically, monostic involvement occurs at 70%e80%, although polyostic involvement should always be considered and screened (48). When the sphenoid bone is involved, primary concern is compression of the optic nerves. Ostiomeatal compression can cause obstructive sinus disorders (4, 33). Superficial bone involvement can cause cosmetic defects. Endoscopic endonasal surgery is primarily used to decompress soft tissue structures, particularly the optic nerve. Intraoperative considerations include careful analysis of the surrounding bony and vascular anatomy, particularly of the carotid artery and its branches. Precise neuronavigation is helpful to identify the optic nerves and vascular structures. There is debate between prophylactic and symptomatic optic nerve decompression, both of which result in visual function preservation or improvement in various surgical series (10, 53, 59). Basilar invagination is a chronic condition of bony brainstem compression caused by the skull base settling onto the atlas and the odontoid process. This can be seen as a result of trauma or degenerative conditions



such as rheumatoid arthritis, Paget’s disease, and chronic renal insufficiency. Brainstem compression can be relieved surgically with various approaches. In the setting of significant anterior compression, the traditional approach has been with the transoral route (19). This approach offers good exposure of the anterior skull base and spine, but is associated with a relatively high morbidity rate. With favorable anatomy, the endonasal endoscopic approach can offer exposure to the foramen magnum, the anterior arch of the atlas, and the upper portion of the odontoid process (12, 31). Depending on the pathology and extent of instability, posterior occipitocervical fusion may be necessary. At present, published reports of this technique are limited to case reports and technical notes without long-term outcomes. Short-term reports do suggest a low incidence of complications with good neurological outcomes (44, 74). CONCLUSION The endoscopic endonasal approach to sellar and parasellar pathology has been demonstrated and validated for a range of disorders. Although the technology continues to develop, its use as an adjunct or primary visualization tool has become increasingly accepted. In all applications of this technology, it is important to weigh the risks and benefits offered to determine safe and effective surgical outcomes. REFERENCES 1. Ahmadi J, Meyers GS, Segall HD, Sharma OP, Hinton DR: Lymphocytic adenohypophysitis: contrast-enhanced MR imaging in five cases. Radiology 195:30-34, 1995. 2. Bell NH: Endocrine complications of sarcoidosis. Endocrinol Metab Clin N Am 20:645-654, 1991. 3. Benveniste RJ, King WA, Walsh J, Lee JS, Naidich TP, Post KD: Surgery for Rathke cleft cysts: technical considerations and outcomes. J Neurosurg 101:577-584, 2004. 4. Berlucchi M, Salsi D, Farina D, Nicolai P: Endoscopic surgery for fibrous dysplasia of the sinonasal tract in pediatric patients. Intern J Ped Otorhinolaryngol 69:43-48, 2005. 5. Bihan H, Christozova V, Dumas JL, Jomaa R, Valeyre D, Tazi A, Reach G, Krivitzky A, Cohen R: Sarcoidosis: clinical, hormonal, and magnetic resonance imaging (MRI) manifestations of hypothalamic-pituitary disease in 9 patients and review of the literature. Medicine 86:259-268, 2007.


6. Campeau RJ, David O, Dowling AM: Pituitary adenoma detected on FDG positron emission tomography in a patient with mucosa-associated lymphoid tissue lymphoma. Clin Nuclear Med 28: 296-298, 2003. 7. Castelnuovo PG, Belli E, Bignami M, Battaglia P, Sberze F, Tomei G: Endoscopic nasal and anterior craniotomy resection for malignant nasoethmoid tumors involving the anterior skull base. Skull Base 16:15-18, 2006. 8. Cavallo LM, Messina A, Esposito F, de Divitiis O, Dal Fabbro M, de Divitiis E, Cappabianca P: Skull base reconstruction in the extended endoscopic transsphenoidal approach for suprasellar lesions. J Neurosurg 107:713-720, 2007. 9. Chakrabarti I, Amar AP, Couldwell W, Weiss MH: Long-term neurological, visual, and endocrine outcomes following transnasal resection of craniopharyngioma. J Neurosurg 102:650-657, 2005. 10. Chen YR, Breidahl A, Chang CN: Optic nerve decompression in fibrous dysplasia: indications, efficacy, and safety. Plastic Reconst Surg 99:22-30; discussion 31-33, 1997. 11. Colli BO, Al-Mefty O: Chordomas of the skull base: follow-up review and prognostic factors. Neurosurg Focus 10:E1, 2001. 12. de Divitiis O, Conti A, Angileri FF, Cardali S, La Torre D, Tschabitscher M: Endoscopic transoraltransclival approach to the brainstem and surrounding cisternal space: anatomic study. Neurosurgery 54: 125-130; discussion 130, 2004.

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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. Received 12 February 2014; accepted 24 July 2014

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