Craniopharyngiomas

CHAPTER 24

Craniopharyngiomas PHILIP V. THEODOSOPOULOS  •  MICHAEL E. SUGHRUE  •  MICHAEL W. McDERMOTT

Craniopharyngiomas are tumors of neuroepithelial origin that arise from squamous cell rests found along the path of the primitive craniopharyngeal duct. Their incidence ranges between 0.5 and 2.5 per 100,000 person years and does not vary by sex or race. Craniopharyngiomas account for 1.2% to 4.6% of all intracranial tumors (Central Brain Tumor Registry of the United States). They exhibit a bimodal distribution, first peaking during childhood (5–14 years) and later peaking in adults ranging from 50 to 74 years; they comprise 5% to 10% of pediatric brain tumors and 1% to 4% of adult brain tumors.1-4 Craniopharyngiomas have a growth pattern that is often in close proximity to the pituitary infundibulum, and can occur within the sella, suprasellar space, or third ventricle, frequently spanning these spaces. These tumors tend to involve a number of neural structures, including the optic nerves, internal carotid arteries (ICAs), and pituitary gland, causing a variety of symptoms. Common clinical presentations include visual dysfunction with symptoms of chiasmatic as well as postchiasmatic compression, hypothalamic dysfunction with behavioral changes ranging from alterations in eating patterns, to apathy, and even obtundation and pituitary dysfunction, often manifesting as hypopituitarism. During the past several years, treatment algorithms have evolved that now incorporate multiple modalities. Surgical resection remains the primary treatment whenever possible. However, the suprasellar space is replete with important neurovascular structures that include the perforator arteries supplying the optic chiasm, hypothalamus, and basal ganglia; their interruption results in permanent neurologic loss of function and disability. Proven therapies with low morbidities include nonradical surgical resection followed by fractionated radiation therapy, radiosurgery, cystic lesion aspiration with implantation of Ommaya reservoir for intracavitary radioisotope, or chemotherapy instillation. More recently, surgical resection via an expanded trans-sphenoidal resection has been advocated as the most direct route to the bulk of the lesion. Although the access provided through this corridor is unparalleled, this technique remains in development because of the lack of appropriate instrumentation to allow safe dissection and the difficulty in providing a watertight closure. The natural history of craniopharyngiomas following treatment is one of recurrence. The need for re-treatment arises when these indolent lesions that exhibit slow growth

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in both their solid and cystic components become symptomatic at various times during a patient’s lifetime.

Classification Several authors who attempted to radiographically classify craniopharyngiomas include Rougerie, Pertuiset, Konovalov, Steno, Hoffman, Samii, and Kassam.5-11 Although none have been universally adopted, these classifications all share the principle of subdividing lesions along the length of extension in the primary vertical axis; the resulting relationship is with the optic chiasm and the third ventricular floor immediately posterior to it. Histologically, craniopharyngiomas are divided into adamantinomatous, papillary, and mixed. The most common form is adamantinomatous, which is often cystic and filled with dark fluid. Columnar or polygonal squamous cells with nuclear palisading arranged in broad bands, cords, and bridges with nodules of compact keratin and dystrophic calcifications are characteristic of the adamantinomatous type (World Health Organization). The wet keratin contrasts with the lamellar flaky keratin in epidermoid cysts. In contrast, papillary craniopharyngiomas consist of sheets of squamous cells that form papillae, lacking nuclear palisading, wet keratin, calcification, and cholesterol deposits.

Anatomy Craniopharyngiomas arise in the parasellar space involving the sella, suprasellar space, and third ventricle. Unlike pituitary tumors, they often adhere to the neurovascular structures of the suprasellar space. Perforating vessels, arising from the anterior communicating artery as well as the proximal ICA, coat the tumor capsule anteriorly as they course toward the optic chiasm and anterior perforating substance. On their way to the basal ganglia and thalamus, laterally and posteriorly perforating vessels that originate from the posterior communicating artery and infrequently from the proximal posterior cerebral arteries are found adherent to the tumor capsule. This close anatomic relationship with vascular structures is an important factor that limits the extent of surgical respectability. Another important limiting factor during surgical resection is the close apposition of craniopharyngiomas to the pituitary infundibulum. This opposition has led some to

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argue that gross total resection cannot be achieved without the section and removal of the involved part of the infundibulum. Although this point remains contested, the morbidity of sacrificing the infundibulum is significant, particularly in pediatric patients.12-19 Diabetes insipidus and hypopituitarism after injury to the infundibulum can impact both the physical and mental growth of patients and limit their daily functional capacity.

Treatment Decision Making The primary treatment of craniopharyngiomas remains surgical. The variability of the tumor extent make is imperative to tailor the surgical approach to the particular lesion. Of several different approaches described, no approach is overall preferred for the majority of the lesions. Adjuvant treatment with radiation therapy is often used; it is necessary in all cases when gross total resection is not achieved and in some tumor recurrences that appear after apparent gross total resection and are likely the result of microscopic residual disease. Although most patients undergo both surgical and radiation treatments, a number of questions need to be addressed on an individual level. Choice of surgical approach depends primarily on the extent of the lesion along the vertical axis (Fig. 24-1). Lesions that are purely intrasellar are preferably approached through a trans-sphenoidal approach. Microscopic or endoscopic corridors have been well described and mimic the approach to pituitary adenomas. Because intrasellar lesions are often cystic, obliteration of the tumor cavity with fat may not be indicated unless a cerebrospinal fluid (CSF) leak is manifested intraoperatively, effectively

allowing for a prolonged outlet that can delay or prevent future reaccumulation of fluid within the cavity. The transsphenoidal route can also be used successfully in the presence of significant suprasellar extension in mostly cystic lesions. The recent development of expanded endoscopic trans-sphenoidal approaches to the sella make the resection of the cyst wall possible when vascular adherence is not a significant issue. Lesions with significant suprasellar extension, particularly when mostly solid, are preferably approached through intracranial corridors. Although expanded endoscopic trans-sphenoidal approaches can provide effective tumor resection, they are considered alternative approaches because of the dearth of appropriate instrumentation, which can cause difficulty in safely managing intraoperative bleeding. Additionally, the dural opening immediately inferior to the suprasellar cistern has proven to be difficult to seal effectively against CSF leaks. Finally, most lesions that are primarily suprasellar arise superior to the pituitary gland, displacing it inferiorly, making the mobilization of the gland itself a necessity for access to the lesion through a trans-sphenoidal route, a surgical maneuver that can result in hypopituitarism. Transcranial routes to the suprasellar space range from a supraorbital corridor to the pterional approach (with or without an orbital or orbitozygomatic osteotomy) to the bifrontal craniotomy. Although each one of these approaches provides a similar exposure to lesions in the suprasellar space, they differ in several important ways. The supraorbital craniotomy, which minimizes soft-tissue morbidity and creates a shorter overall incision, is limited by the size of the frontal sinus. Violation of the frontal

FIGURE 24-1  Approaches to the anterior fossa and sellar region include the trans-sphenoidal, extended transsphenoidal, bifrontal, interhemispheric, pterional, and supraorbital. (From Mayfield Clinic, Cincinnati, OH.)

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sinus through the supraorbital approach can cause a CSF leak that is challenging to fix or a rotation periosteal flap is difficult. Additional limitations of the supraorbital craniotomy include the limited vertical exposure and difficulty with effective brain retraction. The bifrontal subfrontal approach allows for a midline or medial exposure to the suprasellar space and can be the most effective in the presence of a post-fixed chiasm. Conversely, a prefixed chiasm is a limitation that may make access to the lesion all but impossible. Close study of preoperative imaging may give some indication to the location of the chiasm. Specifically, assessment can involve both direct visualization of the chiasm in the absence of severe distortion of normal anatomy and determination of the position of the anterior communicating artery as a surrogate for the location of the chiasm. Nonetheless, large lesions often make it difficult to ascertain the exact position of the chiasm preoperatively; in such cases, this approach can be limiting. The pterional approach is the most versatile for accessing the majority of craniopharyngiomas. It allows for working channels in between the two optic nerves, between the optic nerve and ICA, and between the ICA and oculomotor nerve. The pterional approach is the one most often used for removal of the optic canal roof and anterior clinoid process, steps often necessary for safe mobilization of the optic nerve. The limitation of this approach relates to the location of the ipsilateral optic nerve in the direct line of sight; that is, resection of a significant part of the tumor deep to the nerve is difficult without substantial mobilization of the nerve itself. Tumors that extend extensively into the third ventricle or infrequently arise primarily in the third ventricle pose the greatest surgical challenge, particularly when a significant cystic tumor component is absent. The two major corridors to such lesions are the translamina terminalis approach and the transventricular approach. The lamina terminalis forms the superior continuation of the optic chiasm; its fenestration allows for entry into the anterior third ventricle. It provides direct access to the anterior part of the lesion, yet is limited by the amount of retraction of the optic tracts and the anterior communicating artery necessary for visualization into the third ventricle. In large lesions, determination if a plane of safe dissection exists between the lateral walls of the tumor and hypothalamus can also be challenging. This determination is particularly difficult through a pterional approach that leads to blind dissection of the ipsilateral tumor margin. Transventricular approaches are the most versatile to access large lesions within the third ventricle. A transfrontal or interhemispheric approach can be used to access the lateral ventricle. A transforaminal approach expanded through a subchoroidal extension provides wide access into the third ventricle and good visualization of the lateral margins of the lesion. Limitations of this approach are the significant depth at which the lesion is encountered, the thalamostriate vein that needs to be mobilized, and the potential for injury to the fornices. Radiation therapy is often used as adjuvant therapy. However, a good indication for its use as primary treatment is the rare case of a solid third ventricular lesion with evidence of poor margins with the hypothalamus in an older

patient. The radiation delivery method varies depending on the tumor’s size and characteristics. The usual limitations for radiosurgical treatment, relating to both lesion size and proximity to the optic apparatus, hold true and often lead to the need for fractionated treatment. For primarily cystic tumors, stereotactic- or endoscopictransventricular cyst aspiration through an implanted catheter can allow for intracystic instillation of radioactive material or chemotherapy as well as subsequent percutaneous aspirations of fluid re-accumulation.

Surgical Techniques TRANS-SPHENOIDAL/EXPANDED TRANS-SPHENOIDAL APPROACH The patient is positioned supine; the head in the “sniffing” position allows for elevation above the level of the heart and drainage of bloody material inferiorly away from the surgical field. The traditional trans-sphenoidal approach through a microscopic or endoscopic approach can be used. Intrasellar tumors and mostly cystic craniopharyngiomas even with a significant suprasellar extension are excellent candidates for this approach (Fig. 24-2). The expanded trans-sphenoidal approach requires significant bony removal superiorly past the tuberculum. Importantly, at the beginning of an expanded trans-­ sphenoidal approach, consideration should be given to raising a nasoseptal mucosal flap, which will be used during closure.20 Visualization of the superior aspect of the lesion and its relationship to the undersurface of the optic chiasm is feasible with debulking of the tumor. The perforating vessels and the plane with the optic apparatus need to be sharply dissected under direct vision. However, present endoscopic instrumentation creates an obstacle to effective dissection in many patients. Closure of a traditional or expanded trans-sphenoidal approach has important considerations. Intrasellar lesion resection can be associated with CSF leaks. Obliteration of the sella with abdominal fat grafting is our preferred reconstruction technique; it is reinforced by bone or cartilage obtained during the exposure and by tissue sealant onlay over the entire reconstruction. In the absence of a CSF leak, one may consider leaving the sella open to delay or obviate the re-accumulation of fluid within the cyst. Caution should be used in making this decision depending on the amount of arachnoid descent and herniation within the sella because a delayed CSF leak may ensue. Although a watertight closure of expanded transsphenoidal approaches remains elusive, significant steps have been made during the past several years. Simple fat obliteration proves to be inadequate reconstruction. Multilayer reconstructions and the use of vascularized pedicled mucosal flaps have been promising as an effective reconstruction that can prevent leaks. Use of specialized clips that attempt direct dural reapproximation is an obvious improvement, yet technically very challenging. Deployment of inflatable balloons within the sphenoid sinus can augment the reconstruction. Lumbar subarachnoid drains for temporary CSF diversion offer mechanical advantages but must be balanced by their risk of potential complications,

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Surgicel

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B FIGURE 24-2  The trans-sphenoidal approach may be used for craniopharyngiomas that are primarily intrasellar or when the suprasellar component is cystic. A, An endoscope is inserted through one nostril and instruments are passed through the other nostril. A small portion of the posterior nasal septum is removed and the sphenoid sinus is opened. An opening is made in the sella to expose the tumor. Using curettes and suction, the surgeon debulks and removes the solid portion of the craniopharyngioma. B, Dissection into the cystic portion will release the fluid contents, then decompressing the optic nerves and vascular structures in the suprasellar space. C, The sella is lined with Surgicel and filled with fat harvested from the abdomen. Because the sella does not often support primary closure, the sphenoid sinus is obliterated with fat and closed with cartilage or cortical bone (From Mayfield Clinic, Cincinnati, OH.)

compression of neurovascular structures for the former, and development of pneumocephalus for the latter.

BIFRONTAL CRANIOTOMY The patient is positioned supine with the head slightly extended in three-point pin fixation in the Mayfield clamp. Frameless stereotactic guidance is a useful adjunct for accurate localization of the lesion. A bifrontal incision is marked behind the hairline. Ensuring that the lateral limits are close to the zygomas bilaterally then limits the pressure on the skin flap and avoids flap ischemia. Burr holes are placed on either side of the superior sagittal sinus, approximately 5 cm above the nasion and laterally superior to the keyhole, just lateral to the superior insertion of the temporalis muscle, which is elevated in a limited fashion. The inferior bony cut is preferably made just superior to the frontal sinus; however, transgression of the sinus can be fixed easily with the use of a rotational pericranial flap. The dura is opened in a horizontal incision inferiorly and the superior sagittal sinus is divided with medium vascular clips. The falx is incised and the anterior interhemispheric space is explored (Fig. 24-3). Once the lesion is localized, its relationship to the optic nerves and chiasm is assessed. A prefixed location of the chiasm is a limitation of this approach. In the absence of significant extension into the third ventricle, drilling the tuberculum often allows for increased exposure subchiasmatically. Although exposure is potentially adequate for resection of the lesion, this is a limited corridor for large lesions. Reconstruction of the skull base is crucial for a good outcome.

The anterior interhemispheric approach is perhaps the optimal approach for lesions with extension into the third ventricle. After exposing the chiasm, the surgeon identifies the lamina terminalis, dissects and gently retracts the anterior communicating artery superiorly, and a fenestration into the third ventricle. A midline fenestration at the thinnest area, as far superior to the chiasm as feasible, is most desirable. Correct identification of the optic nerves and optic tracts bilaterally is the safest way to avoid injury to the visual system. Dissection of the tumor from the third ventricle can be safely achieved through the fenestration of the lamina terminalis. The principles that ensure safety and improved outcome are careful identification of the visual apparatus and careful dissection of the lateral margin of the tumor from the hypothalamus. In cases where the plane between the tumor and the lateral wall of third ventricle is not directly visible or absent, one needs to exercise caution to avoid hypothalamic dysfunction.

PTERIONAL CRANIOTOMY The traditional frontotemporal or pterional craniotomy is perhaps the most widely used approach for the treatment of craniopharyngiomas. Reduction of the sphenoid wing is a standard part of this approach because it improves exposure superiorly. Once the basal cisterns are opened, there are two major corridors for lesion resection: the subchiasmatic corridor between the two optic nerves and the opticocarotid corridor between the lateral aspect of the ipsilateral optic nerve and ICA (Fig. 24-4).

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B

A

FIGURE 24-3  The bifrontal interhemispheric approach may be used for craniopharyngiomas in the suprasellar space and is most effective when a post-fixed chiasm is found. A, Bilateral burr holes are made at the pterion, and two additional burr holes are made on either side of the superior sagittal sinus. After a bone flap is cut to connect the burr holes, the posterior wall of the frontal sinus is down-fractured and the flap is removed. The dura is opened and the superior sagittal sinus is tied off and cut. The dural cut is extended down the falx until released. B, The frontal lobes are retracted and adhesions to the olfactory tracts separated. C, The anterior cerebral arteries and optic chiasm are identified and tumor is removed. D, If the tumor growth has prefixed the chiasm, entry into the lamina terminalis exposes tumor in the third ventricle. E, If the tumor growth extends inferiorly, the bone of the tuberculum sella can be drilled to access and remove tumor from the sphenoid sinus. (From Mayfield Clinic, Cincinnati, OH.)

Tuberculum

Post-fixed chiasm

Pituitary stalk

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Sphenoid sinus Chiasm

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This approach is familiar to most neurosurgeons, yet its relative limitation is that the lesion lies posterior to the ipsilateral optic nerve, which often is displaced anteriorly and superiorly as it is splayed over the tumor surface. Manipulation of the ipsilateral optic nerve is a maneuver that endangers visual function. Therefore, one needs to resist the temptation to mobilize the optic nerve for enhanced tumor exposure. Section of the falciform ligament and fenestration of the optic canal, and less often anterior clinoidectomy, are surgical adjuncts that minimize the risk to the ipsilateral vision. The pterional approach allows for direct visualization of the microvasculature surrounding the lesion in the suprasellar cistern. Careful dissection of perforating vessels from the mesial wall of the ICA and the anterior cerebral artery prevents vascular injury to the anterior perforating substance, basal ganglia, hypothalamus, and visual system. The pterional approach is also a versatile one. An orbital osteotomy allows for wide access and improvement in the

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superior aspect of the surgical exposure. Dissection along the ipsilateral optic nerve and chiasm allows for fenestration of the lamina terminalis and access to the part of the lesion extending into the third ventricle. Care should be taken to correctly identify the location of the lamina terminalis. The 15- to 45-degree rotation off the vertical axis can disorient the surgeon with respect to midline, particularly at depth. Confirmation of midline anatomically is crucial with respect to the anterior communicating artery as well as with the use of frameless stereotactic guidance. Offmidline fenestration may result in both poor access to the lesion and injury to the visual system and hypothalamus. The supraorbital craniotomy and its transorbital variant provide a similar degree of exposure with somewhat limited soft tissue dissection (Fig. 24-4B). The temporalis muscle is mobilized to a much lesser degree. With the incision is linear within the eyebrow, there is little need for subcutaneous dissection. The bone flap, which averages 3 × 2 cm, provides adequate access to most lesions in the

24  •  Craniopharyngiomas

Supraorbital approach

Transorbital approach

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A Optic chiasm Lamina terminalis

Optic chiasm

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parasellar space. Care should be taken to avoid injury to the frontalis branch of the facial nerve along the lateral aspect of the incision. The use of frameless stereotactic guidance is recommended to prevent violation of the lateral recess of the frontal sinus. Reconstruction of the sinus from this approach is limited and may result in a transnasal CSF leak that can prove difficult to seal. In our practice, an extensive lateral recess of the frontal sinus is a contraindication for this approach.

TRANSVENTRICULAR APPROACH The transventricular approach is an important surgical corridor for lesions that are primarily third ventricular in location. Although this can be used in most lesions that occupy the third ventricle, the presence of obstructive lateral ventriculomegaly makes this the preferred approach for such lesions. Access to the lateral ventricle can be achieved preferably in a transfrontal fashion in the presence of dilated lateral ventricles and in an interhemispheric fashion in the presence of normal or small-sized lateral ventricles. Our choice patient positions are the neutral supine for the transfrontal approach and the lateral side of access down with the head slightly tilted up for the interhemispheric approach (Fig. 24-5). Once in the lateral ventricle, identification of the foramen of Monro and, in the absence of substantial dilatation

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FIGURE 24-4  The pterional approach is the most versatile to access craniopharyngiomas by allowing the surgeon to work in between the two optic nerves, between the optic nerve and ICA, and between the ICA and oculomotor nerve. A, After a question-mark skin incision is made, a burr hole is placed at the anterior aspect of the superior temporal line. A bone flap is cut with a craniotome and removed. B, View of supraorbital and transorbital keyhole craniotomies. C, The dura is opened and retractors are used to access the optic nerve and chiasmatic cistern. A bipolar is used to coagulate tiny vessels and the lamina terminalis is opened. D, Tumor removal can be accomplished from the third ventricle and suprasellar space with preservation of the pituitary stalk. (From Mayfield Clinic, Cincinnati, OH.)

of the foramen, a subchoroidal dissection permits widening of the operative corridor into the third ventricle. This widening is a necessary maneuver for safe and effective surgery within the third ventricle. Retraction of the fornix as it forms the superior margin of the foramen of Monro, when necessary, should be done carefully to avoid injury to the structure with the potential result of memory dysfunction. Despite the depth at which dissection is performed in this approach, it remains the optimal corridor for exposure of third ventricular lesions. It allows for direct visual inspection of the lateral margins of the tumor and the relationship with the walls of the hypothalamus. At the conclusion of the surgery, the placement of a ventricular catheter through the opening to the lateral ventricle is recommended in cases of symptomatic hydrocephalus preoperatively, an unusually bloody dissection, and the presence of residual tumor that may not relieve pre-existing hydrocephalus. We have found, however, that the need for CSF diversion usually becomes clinically apparent in a delayed fashion, when symptoms appear days to even several weeks postoperatively. The obvious exception to this is acute new-onset obstructive hydrocephalus that results from an immediate postoperative third ventricular hemorrhage. As a result, in our practice, the intraoperative placement of a ventricular catheter in this setting is infrequent.

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Corpus callosum

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B Anterior cerebral artery

Tumor in foramen Monro

FIGURE 24-5  Interhemispheric trans­ ventricular approach. A, A bone flap two thirds anterior and one third posterior to the coronal suture is cut with a craniotome. The frontal lobe is retracted from the falx and cingulate gyrus until the pericallosal arteries and corpus callosum are exposed. B, A 2to 3-cm callosotomy is performed to enter the lateral ventricle. C, The choroid plexus and thalamostriate vein are followed to the foramen of Monro where the tumor is identified. The choroid plexus and thalamostriate vein are coagulated and sectioned. D, The choroidal fissure is opened to remove the tumor. (From Mayfield Clinic, Cincinnati, OH.)

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CYST ASPIRATION Cystic lesions at presentation or at recurrence may be safely treated with catheter drainage. With most symptoms arising from mechanical compression of the surrounding structures by the mass, symptom relief is often achieved by partial or complete collapse of the cystic lesion. Symptomatic resolution is often temporary because fluid tends to reaccumulate within the cyst. As a result, cyst aspiration is not a favored stand-alone treatment. However, the placement of an Ommaya reservoir that could allow for future reaspiration is often an effective treatment for recurrent cystic craniopharyngiomas. The placement of a catheter can be accomplished with stereotactic guidance or in an endoscope-assisted manner. Frameless stereotactic guidance is often accurate enough for safe catheterization of a large symptomatic cystic lesion and is recommended both in the case of simple aspiration, the placement of an Ommaya reservoir, or endoscopeassisted cyst fenestration (Fig. 24-6). In cases of hydrocephalus, an endoscope can safely navigate through the foramen of Monro, then allow for fenestration of a third ventricular cyst, and guide placement of a catheter within the deflated cyst under direct vision. However, it is a rare case

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of a craniopharyngioma that endoscopy can achieve more than fenestration and aspiration. Because most cyst walls have a close adherence of the third ventricle, endoscopic gross total resection is almost never possible.

RADIATION THERAPY External Beam

The standard postoperative treatment for any residual or recurrent tumor is fractionated radiotherapy to a total dose of 60 Gy at 1.8 Gy per fraction. The total dose to the optic nerve ranges between 50 and 54 Gy, a dose generally well tolerated with no effects of vision. Intensity-modulated radiation therapy is the most recent evolution of the 3D-conformal radiation therapy delivery method and promises minimization of radiation dose to surrounding structures. Stereotactic radiosurgery and hypofractionated radiosurgical schemes have been used with good results. However, effective such treatments are ­limited to the treatment of lesions smaller than 3 cm.

Intracavitary Therapy Intracavitary delivery of radiation therapy refers to the instillation of a radioisotope (90 yttrium, 32 phosphorus, or 186 rhenium) into a deflated tumor cyst cavity through an

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C indwelling catheter.21,22 By this method, a high dose (about 150 Gy) can be delivered to the surrounding secretory epithelial layer that lines the cyst with good tumor control. In the literature, results with respect to vision and endocrine function vary widely, and are part of the reason that this technique has not been widely accepted.

Outcomes The primary treatment of craniopharyngiomas remains surgical. The literature indicates rates of gross total resection range widely between 10% to 90%. Yet compilation of all surgical studies reviewed reveals a rough average of 58%—a number that is optimistic in our experience.12,13,23-42 Estimates of gross total resection clearly depend on the postoperative imaging modality used; older studies in which CT was used reported lower rates of observed residuals. Plenty of published evidence suggests that surgical resection is inadequate as the sole treatment for most

FIGURE 24-6  The transventricular endoscopic approach. A, A 3-cm vertical incision, based on the coronal suture, is made 2.5 cm from the midline. A 1-cm burr hole is created slightly anterior to the coronal suture. B, A 12.5 French peel-away sheath introducer is used to cannulate the lateral ventricle. The flexible endoscope is inserted through the cannula to aspirate a large cyst blocking the foramen of Monro. C, Inset showing close-up view. (From Mayfield Clinic, Cincinnati, OH.)

craniopharyngiomas. Although it comes as no surprise that the rates of local tumor control after subtotal resection are generally low, rates after gross total resection are similar ranging between 6% and 57%.25,29-31,34,38,39,43 Operative morbidity includes postoperative visual dysfunction in 5.8% to 19% of patients and postoperative endocrinologic dysfunction in 50% to 100% of patients. Unlike most other brain tumors, an important consideration in the surgical treatment of craniopharyngiomas is perioperative mortality, which ranges between 1.1% to 10% in the early postoperative phase even in the most recent studies.12,23-26,28-32,34,35,38,40,42-45 These rates undoubtedly are associated with the anatomic location of these lesions, and their infiltrative relationship with the hypothalamus and vascular structures. Evidence also exists on the association of improved perioperative outcomes with decreased degrees of surgical resection.46-51 Trans-sphenoidal approaches and their variants with extension to the parasellar region using either the

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FIGURE 24-7  Examples of craniopharyngioma extension (and recommended approach). A, Large recurrent mostly third ventricular lesion (transcallosal). B, Multicystic lesion with lateral extension (pterional). C, Mostly cystic lesion with solid part filling the sella (transsphenoidal). D, Mostly cystic thirdventricular lesion separate from the sella (supraorbital, translamina ­terminalis).

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microscope or endoscope are effective in the treatment of primarily cystic craniopharyngiomas.11,20,52-67 Transventricular endoscopic approaches have a limited utility, primarily for fenestration of cystic lesions, followed by implantation of intracystic catheters under direct visualization.68-71 Several other surgical approaches have been described but have limited clinical applicability and no proven significant benefit in operative outcomes.72-75 A promising exception to this is the supraorbital craniotomy that has an increasing role, replacing the larger subfrontal and pterional approaches in less invasive and smaller tumors.76 Examples of these tumors and recommended approaches are shown in Fig. 24-7 and an overall recommended management of these lesions is shown in Fig. 24-8. The largest body of literature with respect to the radiation treatment of craniopharyngiomas deals with fractionated radiation therapy.35,51,77-91 The majority of the studies include patients treated in the adjuvant setting either postoperatively or at recurrence. Local control ranged between 80% to 100% and follow-up was up to 12 years post-treatment. Morbidity is limited; no visual dysfunction in general is observed when doses less than 60 Gy are used. When compared with patients after gross total resection alone, patients after subtotal resection that was followed by adjuvant fXRT, particularly during the early postoperative period,

demonstrated improved tumor control rates and decreased morbidity.31,44,86,92-97 During the past decade, a number of publications on the treatment of craniopharyngiomas with stereotactic radiosurgery have reported that control rates range between 80% to 90% at 5 years post-treatment; response rates of 58% to 80% have been reported with median marginal dose of 9 to 16 Gy.98-109 Morbidity of this approach appears to be low with visual dysfunction in 6.1% of patients.100 Given the cystic nature of many craniopharyngiomas, stereotactic aspiration of the cystic component with the instillation of radioactive material can be an effective minimally invasive route of treatment. Several types of beta-emitting isotopes have been used, including phosphorus 32, ytrium 90, and rhenium 186.110-120 These colloid preparations can deliver high radiation doses of 100 to 200 Gy in the few surrounding millimeters, effectively treating the wall of cystic lesions, while depositing little radiation in the surrounding normal brain. Used as primary treatment after cyst aspiration or at recurrence, intracavitary radiation therapy has shown local tumor control rates of 70% to 96%.111,112,115 Stereotactic instillation of bleomycin has also shown 57% to 100% response rates.121-126 Although peritumoral edema can be observed postprocedure, it is rarely clinically limiting.121,122

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Provisional imaging diagnosis: craniopharyngioma

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Surgical options: • Standard TS • Extended TS

Surgical options: • Fat graft only closure • Fat plus nasal septal flap

Surgical options: • Pterional • Unilateral subfrontal • Cranio-orbital • Orbitozygomtic

Surgical options: • Subfrontal/translamina terminalis • Transcortical transventricular • Interhemispheric transventricular • Purely endoscopic transventricular

Choice of approach depends on extent of supra-sellar extension

Choice of closure depends on surgeon preference and prior TS approach

Choice of approach depends on extent relative to side and dorsum; all can be endoscopic assisted

Choice of approach depends on surgeon preference and solid vs. cystic; all can be endoscopic assisted

FIGURE 24-8  Diagram of recommended surgical management of craniopharyngiomas as per the authors’ experience.

Conclusions Despite technological advances in both surgical and radiation therapies, craniopharyngiomas remain especially challenging in achieving long-term tumor control at low levels of morbidity. These may be the single type of brain tumor whose surgical treatment even in the most modern series is associated with quantifiable mortality rates in the perioperative setting. The literature supports up front subtotal or near total resection. An effort is made to preserve neurovascular structures surrounding the lesion, including the pituitary stalk in most patients, except when a gross total resection appears clearly within reach. Regardless of the extent of resection, adjuvant radiation therapy should be considered in all patients. After gross total resection, patients should continue to undergo radiographic follow-up to ensure detection of a recurrence, which occurs more often than previously recognized. Considering recurrences are frequent, placement of Ommaya reservoirs for cyst aspiration and intracystic therapies are important parts of the treatment algorithm. KEY REFERENCES Albright AL, Hadjipanayis CG, Lunsford LD, et al. Individualized treatment of pediatric craniopharyngiomas. Childs Nerv Syst. 2005;21: 8–9:649-654. Caldarelli M, Massimi L, Tamburrini G, et al. Long-term results of the surgical treatment of craniopharyngioma: the experience at the Policlinico Gemelli, Catholic University, Rome. Childs Nerv Syst. 2005;21: 8–9:747-757. Cavallo LM, Prevedello DM, Solari D, et al. Extended endoscopic endonasal transsphenoidal approach for residual or recurrent craniopharyngiomas. J Neurosurg. 2009;111(3):578-589.

Chakrabarti I, Amar AP, Couldwell W, et al. Long-term neurological, visual, and endocrine outcomes following transnasal resection of craniopharyngioma. J Neurosurg. 2005;102(4):650-657. Combs SE, Thilmann C, Huber PE, et al. Achievement of long-term local control in patients with craniopharyngiomas using high precision stereotactic radiotherapy. Cancer. 2007;109(11):2308-2314. Derrey S, Blond S, Reyns N, et al. Management of cystic craniopharyngiomas with stereotactic endocavitary irradiation using colloidal 186Re: a retrospective study of 48 consecutive patients. Neurosurgery. 2008;63(6):1045-1053. Dhellemmes P, Vinchon M. Radical resection for craniopharyngiomas in children: surgical technique and clinical results. J Pediatr Endocrinol Metab. 2006;19(suppl 1):329-335. Di Rocco C, Caldarelli M, Tamburrini G, et al. Surgical management of craniopharyngiomas—experience with a pediatric series. J Pediatr Endocrinol Metab. 2006;19(suppl 1):355-366. Fitzek MM, Linggood RM, Adams J, et al. Combined proton and photon irradiation for craniopharyngioma: long-term results of the early cohort of patients treated at Harvard Cyclotron Laboratory and Massachusetts General Hospital. Int J Radiat Oncol Biol Phys. 2006;64(5):1348-1354. Gardner PA, Kassam AB, Snyderman CH, et al. Outcomes following endoscopic, expanded endonasal resection of suprasellar craniopharyngiomas: a case series. J Neurosurg. 2008;109(1):6-16. Gardner PA, Prevedello DM, Kassam AB, et al. The evolution of the endonasal approach for craniopharyngiomas. J Neurosurg. 2008;108(5):1043-1047. Gonc EN, Yordam N, Ozon A, et al. Endocrinological outcome of different treatment options in children with craniopharyngioma: a retrospective analysis of 66 cases. Pediatr Neurosurg. 2004;40(3):112-119. Hukin J, Steinbok P, Lafay-Cousin L, et al. Intracystic bleomycin therapy for craniopharyngioma in children: the Canadian experience. Cancer. 2007;109(10):2124-2131. Kassam AB, Gardner PA, Snyderman CH, et al. Expanded endonasal approach, a fully endoscopic transnasal approach for the resection of midline suprasellar craniopharyngiomas: a new classification based on the infundibulum. J Neurosurg. 2008;108(4):715-728.

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Section One  •  SURGICAL MANAGEMENT OF BRAIN AND SKULL BASE TUMORS

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