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The Frontolateral Approach to Adult Craniopharyngiomas
C H A P T E R
11 The Frontolateral Approach to Adult Craniopharyngiomas Alessandra Mantovani, Manuel Ferreira, Jr., Laligam N. Sekhar Department of Neurological Surgery, University of Washington, Harborview Medical Center, Seattle, WA, USA “Meticulous attention to details in the preoperative and postoperative care of patients, through innumerable small maneuvers before, but especially during and after operation, may avert disaster or shorten convalescence; if neglected, they may cost a patient’s life.” Ernest Sachs, 1949 Craniopharyngiomas are histologically benign, extra-axial, epithelial tumors. Although classified as low-grade neoplasms, the natural history of these tumors is unpredictable and they often present with locally invasive growth patterns and an aggressive clinical course, resulting in significant morbidity. Craniopharyngiomas represent 1e4.6% of all intracranial tumors and 13% of sellar and suprasellar tumors. The incidence of these tumors is estimated as 0.5e2.5 new cases per 1 million population per year. From a histopathological perspective, craniopharyngiomas are broadly classified into adamantinomatous and papillary types. The papillary craniopharyngiomas present almost exclusively in adults, at a mean age of 40e55 years, while adamantinomatous craniopharyngiomas have a bimodal distribution: they occurr either in children aged 5e15 years and in adults aged 40e55 years (Rushing et al., 2007). This chapter mainly discusses the lesions in adults, although it is broadly applicable to children also.
SURGICAL ANATOMY Craniopharyngiomas are solid tumors with a variable cystic component. The adamantinomatous type may be multicystic, containing a cholesterol-rich fluid, while the papillary type usually lacks the cystic component. Calcifications are often present and they may be abundant. These epithelial tumors take origin from the remnants of the craniopharyngeal duct or Rathke’s pouch. Cell rests of this embryonic structure can be found from the infundibulum to
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the pituitary gland. The site of origin of these lesions can predict their growth pattern, as can the appearance of the optic chiasm and the relationship with the surrounding structures. The normal location of the optic chiasm is over the sellar diaphragm and pituitary gland, but it may manifest variations on the horizontal plane. The chiasm is referred to as prefixed when it is positioned superior to the tuberculum sellae, and postfixed when it is superior to the dorsum sellae (Gulsen et al., 2010). According to the position of the optic chiasm, the tumor can grow anteriorly in the case of postfixed chiasm, or posteriorly in the case of prefixed chiasm. Knowledge of the relationship of the tumor with the surrounding structures, especially the location of the optic chiasm and the pituitary gland, is essential when planning the best approach to the lesion. Craniopharyngiomas can grow either below or above the sellar diaphragm. In the first case, the lesion grows intrasellar and suprasellar under the chiasm, which is gradually displaced upward and compressed, as is the floor of the third ventricle. Supradiaphragmatic craniopharyngiomas may have their origin in the pituitary stalk into the chiasmatic cistern or inside the infundibulum. Lesions taking origin from the pituitary stalk can extend inside the subarachnoid space under the chiasm and the floor of the third ventricle. They can be either prechiasmatic or retrochiasmatic, but this second extension is less common and can be due to a prefixed chiasm. Tumors starting from the infundibulum grow behind the chiasm, and they may invade the floor of the third ventricle, extending up to the lateral ventricles. Rarely, the tumor may be confined within the third ventricle, and extend into the lateral ventricles. Giant craniopharyngiomas can grow in various directions and can extend into the posterior fossa. In the case of a lateral growth, the tumor may encase the internal carotid arteries (ICAs) or can be firmly attached to the wall of the cavernous sinus.
PRE-OPERATIVE STUDIES Radiology Magnetic resonance imaging (MRI) provides information about the heterogeneous nature of craniopharyngiomas, their topography, and relation with the other structures. Solid components of the tumor are usually isointense in T1-weighted images and, along with the wall of any cystic components, demonstrate contrast enhancement. On the T2-weighted images, it is sometimes possible to note an arachnoidal plane between the tumor and the neural structures. Fine cut post-gadolinium images are used for identifying the pituitary stalk. Calcifications are often present, and are better visualized by computed tomography (CT). A CT scan can demonstrate the bony anatomy of the skull base as well as the extent of calcification in the tumor. MR angiography or four-vessel angiography is sometimes necessary to show the relationship with the major vessels and their displacement. A catheter intra-arterial angiogram is performed when the ICA or other arteries are encased. Simultaneously, the surgeon may wish to evaluate the collateral circulation by a carotid occlusion test or a cross compression (common carotid compression angiogram).
Endocrinological Evaluation Hypopituitarism or diabetes insipidus (DI) are common manifestations of craniopharyngiomas at diagnosis. However, they are rarely the reason for referral. Since the patient is likely III. SURGICAL APPROACHES
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to have post-operative panhypopituitarism, a complete endocrinological evaluation is performed before any treatment of craniopharyngiomas. The pre-operative endocrinological status is important for adequate pre-operative hormone replacement (particularly corticosteroids and thyroid medications), in order to reduce morbidity.
Neuro-Ophthalmological Evaluation The pre-operative neuro-ophthalmic status should be carefully evaluated in patients. Damage to the visual pathway can be manifested as defects of the visual fields or visual acuity. Among the various visual fields defects, asymmetrical bitemporal hemianopia is the most common and is caused by compression of the optic chiasm. The patient’s visual status is essential for estimating the damage caused by the tumor itself and comparing that to the visual status at follow-up.
Neurobehavioral Evaluation Personality changes and cognitive and memory impairment may be present in adults and should be tested before surgery, for assessing the neurobehavioral status. This will impact the patient’s discharge planning. Memory disorders are caused by a lesion of the mammillary bodies or by any disconnections along the limbic system. Hypothalamic hyperphagia syndrome is seen in patients with lesions located in the hypothalamic region. It is characterized by fatigue, decreased physical activity, uncontrolled appetite, and morbid obesity, and it may be associated with insulin and leptin resistance (Roth, 2011). Patients with large tumors may exhibit behavioral disorders post-operatively on a temporary basis, and the family of the patient should be prepared for this.
GOALS OF SURGERY Surgical resection is the main treatment for craniopharyngiomas. Modern radiosurgery may be used as an option for residual or recurrent lesions (Niranjan et al., 2010; Khamlichi et al., 2013). Complete tumor removal is preferred; if a small remnant is left in order to preserve any structures, then radiation or radiosurgery may be performed. The goals of surgery are control of tumor growth, preservation, or improvement of the patient’s vision, and pituitary/hypothalamic preservation. Other factors influencing the decision about the treatment include the patient’s age and gender, informed consent, and the patient’s goals.
CHOICE OF OPERATIVE APPROACH Different transcranial approaches with variable modifications have been proposed, depending on the preferences and experience of the surgeon and on the position and characteristics of the tumor. The senior authors’ choices have evolved over the years, according to their experience with different approaches; the authors’ currently preferred approaches are summarized in Table 11.1. Retrochiasmatic tumors extending superiorly up to the third
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TABLE 11.1
Authors’ Preferred Approaches for Craniopharyngiomas and Patients Series
Approaches
Characteristic of Tumors
Number of Patients (%) in Our Series
Frontolateral/Transorbital
Most tumors
14 (56%)
Petrosal
Very high extending retrochiasmatic tumors (up to third and lateral ventricles)
4 (16%)
Bifrontal interhemispheric
Very high extending retrochiasmatic tumors, mainly growing inside the third ventricle
3 (12%)
Transsphenoidal endoscopic
Tumor in the midline, patients with intact pituitary function
3 (12%)
Transcallosal
Tumors extending into the lateral ventricle or frontal lobe
1 (4%)
and lateral ventricles can be reached through a transpetrosal approach, as well as prepeduncular or prepontine lesions. The transcallosal approach is reserved for tumors extending into the lateral ventricle or frontal lobe. A bifrontal, interhemispheric approach is sometimes used for tumors mainly growing inside the third ventricle. An endonasal endoscopic transsphenoidal approach minimizes the risk of damage of the pituitary stalk and gland, hypothalamus, and optic apparatus. It is mainly preferred for midline tumors, especially when the pituitary function is intact, and no vascular encasement is present. The frontolateral approach, utilized for most tumors, offers a short distance to the suprasellar region as well as an optimal visualization of the anatomical structures. The basal cisterns can be easily opened, resulting in early cerebrospinal fluid (CSF) drainage and subsequent decompression. The orbital osteotomy permits a lower, basal approach than the classic pterional approach. Compared to the bifrontal approach, the frontolateral approach avoids olfactory nerve injuries and bifrontal lobe retractions (Shirane et al., 2002; Chi et al., 2006; Gerganov et al., 2013).
FRONTOLATERAL APPROACH Position and Initial Exposure The patient is placed in the supine position and the head is fixed in extension, rotated 30 to the opposite side of the craniotomy using a Mayfield head holder. A bicoronal skin incision is made. The flap is then reflected forward, along with pericranium. The pericranial flap should be preserved for the reconstruction of skull base defects. After elevating the temporalis muscle and separating the dura mater in the frontal region, a frontal craniotomy and a small temporal craniotomy are performed. Regardless of the side with worse vision, a right-sided approach is usually preferred, unless the lateral extension of the tumor is mainly on the left side. The orbital osteotomy is then performed on the side of the craniotomy. The frontal and temporal dura mater are carefully separated from the roof and lateral walls of the orbit. The periorbita is separated as well, and the supraorbital nerve is preserved. An osteotomy of the roof and lateral wall of the orbit is performed. Under the surgical microscope, the superior orbital fissure is first unroofed, with the removal of the greater and lesser
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wings of the sphenoid bone. The anterior clinoid process is extradurally removed, completely if possible, and the ipsilateral optic nerve is unroofed extradurally. The frontotemporal dura is opened in a C-shaped fashion, in order to visualize the Sylvian anatomy. The optic nerve and carotid cisterns, as well as the medial part of the Sylvian fissure, are opened. The ipsilateral optic nerve, which is often stretched over the tumor, is relaxed by opening the dural sheath of the optic canal completely. The rest of the anterior clinoid process is removed intradurally, if necessary.
Exposure of the Tumor and Resection At this point the tumor can be well seen, and the operative approach depends upon the extensions of the tumor and the position of the chiasm: normal position, prefixed, or postfixed chiasm. In the case of postfixed chiasm, and when the tumor extends laterally, an approach through the interoptic, optico-carotid, and carotid-tentorial space is preferred (Figure 11.1): the tumor is debulked through the subchiasmatic space, and working through the three avenues, gradually separated from important neurovascular structures and removed. Special attention is paid to the superior hypophyseal arteries, which have to be carefully preserved. For a prefixed chiasm, a translamina terminalis avenue is added to the other routes: the lamina terminalis is opened in the midline behind the crossing of the macular fibers of the optic chiasm, and the craniopharyngioma is dissected from the hypothalamic area and the posterior part of the circle of Willis. More dissection is also performed through the carotid-tentorial, and optico-carotid spaces. The planum sphenoidale is removed after opening a dural flap, and the tumor can be accessed inside an enlarged sella if needed (Figure 11.2A, B). In the case of a cystic lesion, the tumor is drained first, and then the capsule is grasped and gently pulled, while dissection is performed in the arachnoid plane with Rhoton 3, 6, or FIGURE 11.1 Optico-carotid, carotidtentorial space approach for removal of the tumor in the case of a postfixed chiasm. The tumor extends to the lateral side and it is removed through the interoptic, carotidoculomotor and carotid-tentorial spaces, carefully preserving the superior hypophyseal arteries.
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FIGURE 11.2 Approach for prefixed chiasm. A, A translamina terminalis approach is added to the frontolateral approach for the removal of the tumor. B, The planum sphenoidale is drilled and removed after opening a dural flap, to aid in the removal of the sellar and intrachiasmatic tumor.
9 instruments or microscissors. The assistant provides suction (the three hands method). Then the tumor is sharply dissected from the surrounding structures using scissors or fine microinstruments. The main attachments are expected to be to the pituitary stalk or hypothalamic area. The tumor may be quite adherent to arteries as well, even more densely than to nervous structures. In some cases a tiny remnant may be left, in order to preserve the nervous or vascular structure, especially chiasm, ICA, superior hypophyseal arteries, or hypothalamus. Once the tumor has been partially dissected, the pituitary stalk may be identified as a longitudinally striated vascularized structure, which can be seen on any part of the capsule, but most frequently it is found on its fixed entrance through the diaphragm sellae. If the pituitary stalk is not infiltrated by the tumor, then it can be gently dissected by pulling the capsule from the lower part of the pituitary stalk. Otherwise, in order to prevent a recurrence, the stalk may be sacrificed and cut as low as possible (when pituitary functional preservation is not a goal of the surgery). In the case of solid, fleshy, or calcified lesions, the tumor is resected piecemeal with the aid of a pituitary forceps, microscissors, ultrasonic aspirators, or the hand-held CO2 laser (OmniGuide, Boston, Massachusetts). Sometimes the lesion is very firm and needs to be broken into smaller pieces. The tumor should be delivered into the field by a three hands technique. Sometimes, another approach (for example the transpetrosal approach or a subtemporal approach) may be needed for reaching a remaining part of the lesion. Inspection of the tumor bed should be performed under the miscroscope. Also, an angled endoscope can be used to best visualize the surface of the nervous and vascular structures, for ensuring complete resection.
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CLOSURE If the sphenoid sinus was opened, the skull base defect has to be repaired. Abdominal fat is harvested and packed into the upper portion of the sinus. A free and large piece of pericranium is sutured circumferentially to the dural defect, and secured with fibrin glue. If the frontal sinus was opened, the mucosa is stripped off the bone first, then the frontonasal duct is packed with oxidized cellulose and a small abdominal fat graft. The sinus is then completely sealed with bone cement, and covered with a vascularized flap of pericranium, which is sutured to the basal dura. The bone flap and the orbital piece are repositioned and fixed by miniplates. Any bone defect should also be reconstructed with absorbable mesh and bone cement. In young patients, and patients with thin skin, we prefer to use the absorbable plates, in order to obtain the best aesthetic and functional result. The temporal muscle, fascia temporalis and skin layers are sutured in the usual manner.
COMPLICATIONS Diabetes Insipidus Transient diabetes insipidus (DI) is almost always present after surgery and it is due to surgical manipulation of the pituitary stalk. A triphasic response is expected over the first week with DI giving way to hyponatremia, followed by mild DI, or no DI at all. In the post-operative period daily fluid and electrolyte control and balance are essential and serum sodium should be monitored once every 6 hours until stable. If the pituitary stalk was damaged or cut during the operation, patients may present with permanent DI. In this case they may need a long-term vasopressin replacement. A permanent DI can sometimes be present with an intact pituitary stalk: in this case, it may be due to hypothalamic dysfunction.
Hypopituitarism Hypopituitarism is common after the operation. It is usually caused by the compression applied by the tumor to the anterior pituitary gland, but it sometimes can be iatrogenic, caused by a direct injury during surgery. For patients with apparently intact pituitary function it is recommended to check the morning fasting cortisol level and to undergo a delayed cosyntropin stimulation test to assess the function of the pituitaryeadrenal gland axis. Hypoadrenalism is very common and should always be suspected: for this reason, high doses of corticosteroids are provided before the operation and in the first 2 weeks after surgery. They may then be tapered. Further endocrinological disorders may be experienced and they are treated according to the hormone levels and physiological requirements. The patient should be managed post-operatively by an endocrinologist.
Injury to the ICA The arachnoid plane between the tumor capsule and the ICA usually allows a sharp dissection of the lesion. The tumor capsule may sometimes be firmly adherent to the ICA, however. Special
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attention should be paid to patients who have undergone previous operations or radiosurgery for the tumor. If damage to the ICA occurs, the best option for repairing is by direct suture under temporary occlusion. Rarely, some patients may need a bypass when a direct repair is not feasible.
Injury of the Optic Nerve and Chiasm Injuries of the optic nerve and chiasm are quite rare. They may occur due to excessive retraction and decompression of these structures. The chiasm and optic nerve are very sensitive to vascular damage as well. The superior hypophyseal arteries may be stretched or damaged during their tortuous course to the optic nerve (van Overbeeke and Sekhar, 2003).
Vasospasm Vasospasm can occur up to 4 weeks after surgery, and can be the cause of delayed neurological deficits. Special vigilance is needed, especially in patients with tumors encasing the arteries. When this complication is recognized, prompt treatment is started, consisting of hydration, induced arterial hypertension, and endovascular angioplasty when needed.
OUR SERIES From September 2005 to November 2013, 25 patients with craniopharyngiomas underwent surgical resection at Haborview Medical Center in Seattle, Washington, by the two senior authors (LNS and MFJ). Thirteen patients were men and 12 were women, with ages ranging from 14 to 81 years (mean standard deviation 42.6 19 years). All patients were subjected to pre-operative MRI, endocrinological, and neuro-ophthalmological evaluations. Nine craniopharyngiomas (36%) were positioned in the sellar/suprasellar region, 14 (56%) were suprasellar retrochiasmatic lesions, seven of them extending to the third ventricle and one also extending to the posterior fossa. One lesion (4%) was positioned predominantly in the third ventricle, the last one (4%) was a sellar lesion extending to the right side. The mean pre-operative modified Rankin Scale (mRS) score was 1.16, ranging from 0 to 3. A total of 15/25 patients (60%) presented with visual loss, 10/25 patients (40%) with endocrinological dysfunctions, mainly due to anterior hypopituitarism. Eight patients (32%) had previous operations and presented with a remnant or a recurrent lesion. Table 11.1 shows the operative approaches utilized in this series according to the characteristics of the tumors. Seventeen patients (68%) had a gross total resection of the tumor, while a tiny remnant was left in the other eight patients (32%), in order to preserve nervous or vascular structures. One patient, who presented in a poor condition, died during hospitalization due to multiple medical complications. The length of the follow-up for this series is 29.37 23.74 months (mean standard deviation) and the mean mRS score at the last follow-up was 1.3. Table 11.2 shows the patients’ visual and endocrine status at presentation and at follow-up. A total of 7/15 (46.7%) patients presenting with visual loss improved postoperatively. The improvement was not as positive for patients with endocrine deficiency: only 1/10 patient improved after surgery, while 10/15 (66.7%) patients presenting with intact pituitary function manifested hypopituitarism or DI at the follow-up.
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TABLE 11.2
Visual and Endocrine Patients’ Status at Presentation and at Follow-up Pre-operative status
Visual status
Normal: 10 (40%)
Follow-up Normal: 9 (90%) Visual deficit: 1 (10%)
Visual loss: 15 (60%)
Stable: 8 (53.3%) Improved: 7 (46.7%)
Endocrine status
Normal: 15 (60%)
Normal: 5 (33.3%) Endocrine deficiency/DI: 10 (66.7%)
Endocrine deficiency: 10 (40%)
Stable: 9 (90%) Improved: 1 (10%)
Illustrative Case 1 This is a 65-year-old man who presented with increasing mental confusion. The MRI showed a suprasellar, retrochiasmatic lesion, measuring 25 x 25 x 31 mm (Figure 11.3A, B, C). He underwent a frontolateral approach with a total tumor resection. After the operation he manifested hypopituitarism, which necessitated hormonal replacement. At the last followup, 4 years after surgery, the patient exhibited chronic hypopituitarism, and no other symptoms. His MRI showed no evidence of tumor recurrence (Figure 11.4A, B, C).
Illustrative Case 2 This 17-year-old boy presented with 2 months of severe headaches, fatigue, and defects of the visual fields. His MRI showed the presence of a retrosellar lesion extending to the posterior fossa, with severe compression of the hypothalamus, the third ventricle, and the
(A)
(C)
(B)
FIGURE 11.3 A, B, C: Pre-operative MRI for illustrative case 1. Suprasellar, retrochiasmatic lesion, removed via frontolateral approach.
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(B)
(A)
FIGURE 11.4
(C)
A, B, C: Post-operative MRI for illustrative case 1, showing a complete removal of the tumor.
(A)
(B)
(C)
FIGURE 11.5 A, B, C: Pre-operative MRI for illustrative case 2. Retrosellar lesion extending to the posterior fossa, with severe compression of the hypothalamus, the third ventricle, and the brainstem, removed via the transpetrosal approach.
brainstem (Figure 11.5A, B, C). The pre-operative endocrinological evaluation also revealed low levels of cortisol and testosterone. He underwent a complete removal of the lesion through a presigmoidal transpetrosal approach. During the post-operative period the patient experienced transient DI, and transient cranial nerves III and VI palsy, which recovered completely within 3 months. At the last follow-up, 3 years after surgery, the patient was doing well, and was attending college. He had no endocrine or visual deficits and his MRI did not show any recurrence (Figure 11.6A, B).
Illustrative Case 3 This 20-year-old man had undergone removal of a craniopharyngioma at the age of 6 and had been followed by his endocrinologist for hypopituitarism. He presented to the emergency room complaining of near complete loss of vision in the left eye for about 4 days. His MRI showed a recurrent complex suprasellar retrochiasmatic lesion, measuring 17 x 18 x 18 mm, with encasement of the basilar artery (Figure 11.7A, B, C). Because of the
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(A)
FIGURE 11.6
(B)
A, B: Post-operative MRI for illustrative case 2. The tumor was completely removed, no endocrine
deficiency.
(A)
(B)
(C)
FIGURE 11.7 A, B, C: Pre-operative MRI for illustrative case 3. Recurrent complex suprasellar retrochiasmatic lesion, with encasement of the basilar artery. A two-stage surgery was planned, and the tumor was removed via the frontolateral approach first and the tranpetrosal approach in the second stage.
complexity and the extension of the lesion, an operation in two stages was planned. He underwent a frontolateral approach with a partial removal of the lesion first, followed by a transpetrosal approach for removing the residual posterior part of the craniopharyngioma located anterior to the brain stem with encasement of the basilar artery. Post-operatively he manifested hydrocephalus and a lumboperitoneal shunt was placed. At the last followup, 5 years after the operation, the patient was doing well, and functioning normally. He had completed high school, and was seeking employment. He had chronic hypopituitarism and visual deficit in the left eye: he had light perception, but was unable to discern objects with it. His MRI showed a stable small amount of enhancement in the left parasellar region (Figure 11.8A, B).
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(B)
(A)
FIGURE 11.8 A, B: Post-operative MRI for illustrative case 3, showing a near-complete tumor removal, with a stable small amount of enhancement in the left parasellar region.
Illustrative Case 4 This is a 29-year-old woman presenting with progressive vision loss that was greater in the left eye than in the right, and bilateral visual fields cuts. Her MRI showed a suprasellar retrochiasmatic lesion, extending up to the third ventricle (Figure 11.9A, B, C). She underwent an endonasal transsphenoidal approach, with a complete removal of the tumor. Her post-operative course was complicated by a CSF leak requiring a re-exploration, and the placement of a nasal septal flap. At her last follow-up, 16 months after surgery, she was doing very well, not presenting any symptoms. Her visual deficits had completely recovered, she had intact pituitary function, no signs of DI, and she was pregnant. Her MRI did not show any recurrence (Figure 11.10A, B).
(A)
(B)
(C)
FIGURE 11.9 A, B, C: Pre-operative MRI for illustrative case 4. Suprasellar retrochiasmatic lesion, extending up to the third ventricle, removed via transsphenoidal approach.
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(A)
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(B)
A, B: Post-operative MRI for illustrative case 4. The tumor was completely removed and the pituitary stalk was intact.
FIGURE 11.10
CONCLUSIONS Craniopharyngiomas in adults are complex lesions. The majority of tumors can be removed completely, or nearly completely, with the preservation or the improvement of patients’ vision. The frontolateral, transpetrosal, and endoscopic transsphenoidal are the currently preferred operative approaches. A careful endocrine management is required in both the pre-operative and post-operative phases.
Acknowledgments The illustrations were prepared by Jennifer Pryll, medical illustrator. Doctor Laligam N. Sekhar retains the copyright for the illustrations.
References Chi, J.H., Parsa, A.T., Berger, M.S., Kunwar, S., McDermott, M.W., Oct 2006. Extended bifrontal craniotomy for midline anterior fossa meningiomas: minimization of retraction-related edema and surgical outcomes. Neurosurgery 59 (4 Suppl. 2). ONS426e433; discussion ONS433e424. Gerganov, V., Metwali, H., Samii, A., Fahlbusch, R., Samii, M., Nov 22 2013. Microsurgical resection of extensive craniopharyngiomas using a frontolateral approach: operative technique and outcome. J. Neurosurg.. Gulsen, S., Dinc, A.H., Unal, M., Canturk, N., Altinors, N., Mar 2010. Characterization of the anatomic location of the pituitary stalk and its relationship to the dorsum sellae, tuberculum sellae and chiasmatic cistern. J. Korean. Neurosurg. Soc. 47 (3), 169e173. Khamlichi, A.E., Melhaoui, A., Arkha, Y., Jiddane, M., Gueddari, B.K., 2013. Role of gamma knife radiosurgery in the management of pituitary adenomas and craniopharyngiomas. Acta. Neurochir. Suppl. 116, 49e54. Niranjan, A., Kano, H., Mathieu, D., Kondziolka, D., Flickinger, J.C., Lunsford, L.D., Sep 1 2010. Radiosurgery for craniopharyngioma. Int. J. Radiat. Oncol. Biol. Phys. 78 (1), 64e71. Roth, C.L., 2011. Hypothalamic obesity in patients with craniopharyngioma: profound changes of several weight regulatory circuits. Front. endocrinol. 2, 49. Rushing, E.J.G.F., Paulus, W., Burger, P.C., 2007. Craniopharyngioma. In: Louis, D.N.O.H., Wiestler, O.D., Cavenee, W.K. (Eds.), WHO Classification of Tumours of the Central Nervous System, fourth ed. IARC Press, Lyon, pp. 238e240.
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Sachs, E., 1949. Diagnosis and treatment of brain tumors and care of the neurosurgical patient. C.V. Mosby Company, St. Louis, p 13. Shirane, R., Ching-Chan, S., Kusaka, Y., Jokura, H., Yoshimoto, T., Apr 2002. Surgical outcomes in 31 patients with craniopharyngiomas extending outside the suprasellar cistern: an evaluation of the frontobasal interhemispheric approach. J. Neurosurg. 96 (4), 704e712. van Overbeeke, J., Sekhar, L., Jun 2003. Microanatomy of the blood supply to the optic nerve. Orbit 22 (2), 81e88.
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11 The Frontolateral Approach to Adult Craniopharyngiomas Alessandra Mantovani, Manuel Ferreira, Jr., Laligam N. Sekhar Department of Neurological Surgery, University of Washington, Harborview Medical Center, Seattle, WA, USA “Meticulous attention to details in the preoperative and postoperative care of patients, through innumerable small maneuvers before, but especially during and after operation, may avert disaster or shorten convalescence; if neglected, they may cost a patient’s life.” Ernest Sachs, 1949 Craniopharyngiomas are histologically benign, extra-axial, epithelial tumors. Although classified as low-grade neoplasms, the natural history of these tumors is unpredictable and they often present with locally invasive growth patterns and an aggressive clinical course, resulting in significant morbidity. Craniopharyngiomas represent 1e4.6% of all intracranial tumors and 13% of sellar and suprasellar tumors. The incidence of these tumors is estimated as 0.5e2.5 new cases per 1 million population per year. From a histopathological perspective, craniopharyngiomas are broadly classified into adamantinomatous and papillary types. The papillary craniopharyngiomas present almost exclusively in adults, at a mean age of 40e55 years, while adamantinomatous craniopharyngiomas have a bimodal distribution: they occurr either in children aged 5e15 years and in adults aged 40e55 years (Rushing et al., 2007). This chapter mainly discusses the lesions in adults, although it is broadly applicable to children also.
SURGICAL ANATOMY Craniopharyngiomas are solid tumors with a variable cystic component. The adamantinomatous type may be multicystic, containing a cholesterol-rich fluid, while the papillary type usually lacks the cystic component. Calcifications are often present and they may be abundant. These epithelial tumors take origin from the remnants of the craniopharyngeal duct or Rathke’s pouch. Cell rests of this embryonic structure can be found from the infundibulum to
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the pituitary gland. The site of origin of these lesions can predict their growth pattern, as can the appearance of the optic chiasm and the relationship with the surrounding structures. The normal location of the optic chiasm is over the sellar diaphragm and pituitary gland, but it may manifest variations on the horizontal plane. The chiasm is referred to as prefixed when it is positioned superior to the tuberculum sellae, and postfixed when it is superior to the dorsum sellae (Gulsen et al., 2010). According to the position of the optic chiasm, the tumor can grow anteriorly in the case of postfixed chiasm, or posteriorly in the case of prefixed chiasm. Knowledge of the relationship of the tumor with the surrounding structures, especially the location of the optic chiasm and the pituitary gland, is essential when planning the best approach to the lesion. Craniopharyngiomas can grow either below or above the sellar diaphragm. In the first case, the lesion grows intrasellar and suprasellar under the chiasm, which is gradually displaced upward and compressed, as is the floor of the third ventricle. Supradiaphragmatic craniopharyngiomas may have their origin in the pituitary stalk into the chiasmatic cistern or inside the infundibulum. Lesions taking origin from the pituitary stalk can extend inside the subarachnoid space under the chiasm and the floor of the third ventricle. They can be either prechiasmatic or retrochiasmatic, but this second extension is less common and can be due to a prefixed chiasm. Tumors starting from the infundibulum grow behind the chiasm, and they may invade the floor of the third ventricle, extending up to the lateral ventricles. Rarely, the tumor may be confined within the third ventricle, and extend into the lateral ventricles. Giant craniopharyngiomas can grow in various directions and can extend into the posterior fossa. In the case of a lateral growth, the tumor may encase the internal carotid arteries (ICAs) or can be firmly attached to the wall of the cavernous sinus.
PRE-OPERATIVE STUDIES Radiology Magnetic resonance imaging (MRI) provides information about the heterogeneous nature of craniopharyngiomas, their topography, and relation with the other structures. Solid components of the tumor are usually isointense in T1-weighted images and, along with the wall of any cystic components, demonstrate contrast enhancement. On the T2-weighted images, it is sometimes possible to note an arachnoidal plane between the tumor and the neural structures. Fine cut post-gadolinium images are used for identifying the pituitary stalk. Calcifications are often present, and are better visualized by computed tomography (CT). A CT scan can demonstrate the bony anatomy of the skull base as well as the extent of calcification in the tumor. MR angiography or four-vessel angiography is sometimes necessary to show the relationship with the major vessels and their displacement. A catheter intra-arterial angiogram is performed when the ICA or other arteries are encased. Simultaneously, the surgeon may wish to evaluate the collateral circulation by a carotid occlusion test or a cross compression (common carotid compression angiogram).
Endocrinological Evaluation Hypopituitarism or diabetes insipidus (DI) are common manifestations of craniopharyngiomas at diagnosis. However, they are rarely the reason for referral. Since the patient is likely III. SURGICAL APPROACHES
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to have post-operative panhypopituitarism, a complete endocrinological evaluation is performed before any treatment of craniopharyngiomas. The pre-operative endocrinological status is important for adequate pre-operative hormone replacement (particularly corticosteroids and thyroid medications), in order to reduce morbidity.
Neuro-Ophthalmological Evaluation The pre-operative neuro-ophthalmic status should be carefully evaluated in patients. Damage to the visual pathway can be manifested as defects of the visual fields or visual acuity. Among the various visual fields defects, asymmetrical bitemporal hemianopia is the most common and is caused by compression of the optic chiasm. The patient’s visual status is essential for estimating the damage caused by the tumor itself and comparing that to the visual status at follow-up.
Neurobehavioral Evaluation Personality changes and cognitive and memory impairment may be present in adults and should be tested before surgery, for assessing the neurobehavioral status. This will impact the patient’s discharge planning. Memory disorders are caused by a lesion of the mammillary bodies or by any disconnections along the limbic system. Hypothalamic hyperphagia syndrome is seen in patients with lesions located in the hypothalamic region. It is characterized by fatigue, decreased physical activity, uncontrolled appetite, and morbid obesity, and it may be associated with insulin and leptin resistance (Roth, 2011). Patients with large tumors may exhibit behavioral disorders post-operatively on a temporary basis, and the family of the patient should be prepared for this.
GOALS OF SURGERY Surgical resection is the main treatment for craniopharyngiomas. Modern radiosurgery may be used as an option for residual or recurrent lesions (Niranjan et al., 2010; Khamlichi et al., 2013). Complete tumor removal is preferred; if a small remnant is left in order to preserve any structures, then radiation or radiosurgery may be performed. The goals of surgery are control of tumor growth, preservation, or improvement of the patient’s vision, and pituitary/hypothalamic preservation. Other factors influencing the decision about the treatment include the patient’s age and gender, informed consent, and the patient’s goals.
CHOICE OF OPERATIVE APPROACH Different transcranial approaches with variable modifications have been proposed, depending on the preferences and experience of the surgeon and on the position and characteristics of the tumor. The senior authors’ choices have evolved over the years, according to their experience with different approaches; the authors’ currently preferred approaches are summarized in Table 11.1. Retrochiasmatic tumors extending superiorly up to the third
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TABLE 11.1
Authors’ Preferred Approaches for Craniopharyngiomas and Patients Series
Approaches
Characteristic of Tumors
Number of Patients (%) in Our Series
Frontolateral/Transorbital
Most tumors
14 (56%)
Petrosal
Very high extending retrochiasmatic tumors (up to third and lateral ventricles)
4 (16%)
Bifrontal interhemispheric
Very high extending retrochiasmatic tumors, mainly growing inside the third ventricle
3 (12%)
Transsphenoidal endoscopic
Tumor in the midline, patients with intact pituitary function
3 (12%)
Transcallosal
Tumors extending into the lateral ventricle or frontal lobe
1 (4%)
and lateral ventricles can be reached through a transpetrosal approach, as well as prepeduncular or prepontine lesions. The transcallosal approach is reserved for tumors extending into the lateral ventricle or frontal lobe. A bifrontal, interhemispheric approach is sometimes used for tumors mainly growing inside the third ventricle. An endonasal endoscopic transsphenoidal approach minimizes the risk of damage of the pituitary stalk and gland, hypothalamus, and optic apparatus. It is mainly preferred for midline tumors, especially when the pituitary function is intact, and no vascular encasement is present. The frontolateral approach, utilized for most tumors, offers a short distance to the suprasellar region as well as an optimal visualization of the anatomical structures. The basal cisterns can be easily opened, resulting in early cerebrospinal fluid (CSF) drainage and subsequent decompression. The orbital osteotomy permits a lower, basal approach than the classic pterional approach. Compared to the bifrontal approach, the frontolateral approach avoids olfactory nerve injuries and bifrontal lobe retractions (Shirane et al., 2002; Chi et al., 2006; Gerganov et al., 2013).
FRONTOLATERAL APPROACH Position and Initial Exposure The patient is placed in the supine position and the head is fixed in extension, rotated 30 to the opposite side of the craniotomy using a Mayfield head holder. A bicoronal skin incision is made. The flap is then reflected forward, along with pericranium. The pericranial flap should be preserved for the reconstruction of skull base defects. After elevating the temporalis muscle and separating the dura mater in the frontal region, a frontal craniotomy and a small temporal craniotomy are performed. Regardless of the side with worse vision, a right-sided approach is usually preferred, unless the lateral extension of the tumor is mainly on the left side. The orbital osteotomy is then performed on the side of the craniotomy. The frontal and temporal dura mater are carefully separated from the roof and lateral walls of the orbit. The periorbita is separated as well, and the supraorbital nerve is preserved. An osteotomy of the roof and lateral wall of the orbit is performed. Under the surgical microscope, the superior orbital fissure is first unroofed, with the removal of the greater and lesser
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wings of the sphenoid bone. The anterior clinoid process is extradurally removed, completely if possible, and the ipsilateral optic nerve is unroofed extradurally. The frontotemporal dura is opened in a C-shaped fashion, in order to visualize the Sylvian anatomy. The optic nerve and carotid cisterns, as well as the medial part of the Sylvian fissure, are opened. The ipsilateral optic nerve, which is often stretched over the tumor, is relaxed by opening the dural sheath of the optic canal completely. The rest of the anterior clinoid process is removed intradurally, if necessary.
Exposure of the Tumor and Resection At this point the tumor can be well seen, and the operative approach depends upon the extensions of the tumor and the position of the chiasm: normal position, prefixed, or postfixed chiasm. In the case of postfixed chiasm, and when the tumor extends laterally, an approach through the interoptic, optico-carotid, and carotid-tentorial space is preferred (Figure 11.1): the tumor is debulked through the subchiasmatic space, and working through the three avenues, gradually separated from important neurovascular structures and removed. Special attention is paid to the superior hypophyseal arteries, which have to be carefully preserved. For a prefixed chiasm, a translamina terminalis avenue is added to the other routes: the lamina terminalis is opened in the midline behind the crossing of the macular fibers of the optic chiasm, and the craniopharyngioma is dissected from the hypothalamic area and the posterior part of the circle of Willis. More dissection is also performed through the carotid-tentorial, and optico-carotid spaces. The planum sphenoidale is removed after opening a dural flap, and the tumor can be accessed inside an enlarged sella if needed (Figure 11.2A, B). In the case of a cystic lesion, the tumor is drained first, and then the capsule is grasped and gently pulled, while dissection is performed in the arachnoid plane with Rhoton 3, 6, or FIGURE 11.1 Optico-carotid, carotidtentorial space approach for removal of the tumor in the case of a postfixed chiasm. The tumor extends to the lateral side and it is removed through the interoptic, carotidoculomotor and carotid-tentorial spaces, carefully preserving the superior hypophyseal arteries.
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FIGURE 11.2 Approach for prefixed chiasm. A, A translamina terminalis approach is added to the frontolateral approach for the removal of the tumor. B, The planum sphenoidale is drilled and removed after opening a dural flap, to aid in the removal of the sellar and intrachiasmatic tumor.
9 instruments or microscissors. The assistant provides suction (the three hands method). Then the tumor is sharply dissected from the surrounding structures using scissors or fine microinstruments. The main attachments are expected to be to the pituitary stalk or hypothalamic area. The tumor may be quite adherent to arteries as well, even more densely than to nervous structures. In some cases a tiny remnant may be left, in order to preserve the nervous or vascular structure, especially chiasm, ICA, superior hypophyseal arteries, or hypothalamus. Once the tumor has been partially dissected, the pituitary stalk may be identified as a longitudinally striated vascularized structure, which can be seen on any part of the capsule, but most frequently it is found on its fixed entrance through the diaphragm sellae. If the pituitary stalk is not infiltrated by the tumor, then it can be gently dissected by pulling the capsule from the lower part of the pituitary stalk. Otherwise, in order to prevent a recurrence, the stalk may be sacrificed and cut as low as possible (when pituitary functional preservation is not a goal of the surgery). In the case of solid, fleshy, or calcified lesions, the tumor is resected piecemeal with the aid of a pituitary forceps, microscissors, ultrasonic aspirators, or the hand-held CO2 laser (OmniGuide, Boston, Massachusetts). Sometimes the lesion is very firm and needs to be broken into smaller pieces. The tumor should be delivered into the field by a three hands technique. Sometimes, another approach (for example the transpetrosal approach or a subtemporal approach) may be needed for reaching a remaining part of the lesion. Inspection of the tumor bed should be performed under the miscroscope. Also, an angled endoscope can be used to best visualize the surface of the nervous and vascular structures, for ensuring complete resection.
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CLOSURE If the sphenoid sinus was opened, the skull base defect has to be repaired. Abdominal fat is harvested and packed into the upper portion of the sinus. A free and large piece of pericranium is sutured circumferentially to the dural defect, and secured with fibrin glue. If the frontal sinus was opened, the mucosa is stripped off the bone first, then the frontonasal duct is packed with oxidized cellulose and a small abdominal fat graft. The sinus is then completely sealed with bone cement, and covered with a vascularized flap of pericranium, which is sutured to the basal dura. The bone flap and the orbital piece are repositioned and fixed by miniplates. Any bone defect should also be reconstructed with absorbable mesh and bone cement. In young patients, and patients with thin skin, we prefer to use the absorbable plates, in order to obtain the best aesthetic and functional result. The temporal muscle, fascia temporalis and skin layers are sutured in the usual manner.
COMPLICATIONS Diabetes Insipidus Transient diabetes insipidus (DI) is almost always present after surgery and it is due to surgical manipulation of the pituitary stalk. A triphasic response is expected over the first week with DI giving way to hyponatremia, followed by mild DI, or no DI at all. In the post-operative period daily fluid and electrolyte control and balance are essential and serum sodium should be monitored once every 6 hours until stable. If the pituitary stalk was damaged or cut during the operation, patients may present with permanent DI. In this case they may need a long-term vasopressin replacement. A permanent DI can sometimes be present with an intact pituitary stalk: in this case, it may be due to hypothalamic dysfunction.
Hypopituitarism Hypopituitarism is common after the operation. It is usually caused by the compression applied by the tumor to the anterior pituitary gland, but it sometimes can be iatrogenic, caused by a direct injury during surgery. For patients with apparently intact pituitary function it is recommended to check the morning fasting cortisol level and to undergo a delayed cosyntropin stimulation test to assess the function of the pituitaryeadrenal gland axis. Hypoadrenalism is very common and should always be suspected: for this reason, high doses of corticosteroids are provided before the operation and in the first 2 weeks after surgery. They may then be tapered. Further endocrinological disorders may be experienced and they are treated according to the hormone levels and physiological requirements. The patient should be managed post-operatively by an endocrinologist.
Injury to the ICA The arachnoid plane between the tumor capsule and the ICA usually allows a sharp dissection of the lesion. The tumor capsule may sometimes be firmly adherent to the ICA, however. Special
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attention should be paid to patients who have undergone previous operations or radiosurgery for the tumor. If damage to the ICA occurs, the best option for repairing is by direct suture under temporary occlusion. Rarely, some patients may need a bypass when a direct repair is not feasible.
Injury of the Optic Nerve and Chiasm Injuries of the optic nerve and chiasm are quite rare. They may occur due to excessive retraction and decompression of these structures. The chiasm and optic nerve are very sensitive to vascular damage as well. The superior hypophyseal arteries may be stretched or damaged during their tortuous course to the optic nerve (van Overbeeke and Sekhar, 2003).
Vasospasm Vasospasm can occur up to 4 weeks after surgery, and can be the cause of delayed neurological deficits. Special vigilance is needed, especially in patients with tumors encasing the arteries. When this complication is recognized, prompt treatment is started, consisting of hydration, induced arterial hypertension, and endovascular angioplasty when needed.
OUR SERIES From September 2005 to November 2013, 25 patients with craniopharyngiomas underwent surgical resection at Haborview Medical Center in Seattle, Washington, by the two senior authors (LNS and MFJ). Thirteen patients were men and 12 were women, with ages ranging from 14 to 81 years (mean standard deviation 42.6 19 years). All patients were subjected to pre-operative MRI, endocrinological, and neuro-ophthalmological evaluations. Nine craniopharyngiomas (36%) were positioned in the sellar/suprasellar region, 14 (56%) were suprasellar retrochiasmatic lesions, seven of them extending to the third ventricle and one also extending to the posterior fossa. One lesion (4%) was positioned predominantly in the third ventricle, the last one (4%) was a sellar lesion extending to the right side. The mean pre-operative modified Rankin Scale (mRS) score was 1.16, ranging from 0 to 3. A total of 15/25 patients (60%) presented with visual loss, 10/25 patients (40%) with endocrinological dysfunctions, mainly due to anterior hypopituitarism. Eight patients (32%) had previous operations and presented with a remnant or a recurrent lesion. Table 11.1 shows the operative approaches utilized in this series according to the characteristics of the tumors. Seventeen patients (68%) had a gross total resection of the tumor, while a tiny remnant was left in the other eight patients (32%), in order to preserve nervous or vascular structures. One patient, who presented in a poor condition, died during hospitalization due to multiple medical complications. The length of the follow-up for this series is 29.37 23.74 months (mean standard deviation) and the mean mRS score at the last follow-up was 1.3. Table 11.2 shows the patients’ visual and endocrine status at presentation and at follow-up. A total of 7/15 (46.7%) patients presenting with visual loss improved postoperatively. The improvement was not as positive for patients with endocrine deficiency: only 1/10 patient improved after surgery, while 10/15 (66.7%) patients presenting with intact pituitary function manifested hypopituitarism or DI at the follow-up.
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TABLE 11.2
Visual and Endocrine Patients’ Status at Presentation and at Follow-up Pre-operative status
Visual status
Normal: 10 (40%)
Follow-up Normal: 9 (90%) Visual deficit: 1 (10%)
Visual loss: 15 (60%)
Stable: 8 (53.3%) Improved: 7 (46.7%)
Endocrine status
Normal: 15 (60%)
Normal: 5 (33.3%) Endocrine deficiency/DI: 10 (66.7%)
Endocrine deficiency: 10 (40%)
Stable: 9 (90%) Improved: 1 (10%)
Illustrative Case 1 This is a 65-year-old man who presented with increasing mental confusion. The MRI showed a suprasellar, retrochiasmatic lesion, measuring 25 x 25 x 31 mm (Figure 11.3A, B, C). He underwent a frontolateral approach with a total tumor resection. After the operation he manifested hypopituitarism, which necessitated hormonal replacement. At the last followup, 4 years after surgery, the patient exhibited chronic hypopituitarism, and no other symptoms. His MRI showed no evidence of tumor recurrence (Figure 11.4A, B, C).
Illustrative Case 2 This 17-year-old boy presented with 2 months of severe headaches, fatigue, and defects of the visual fields. His MRI showed the presence of a retrosellar lesion extending to the posterior fossa, with severe compression of the hypothalamus, the third ventricle, and the
(A)
(C)
(B)
FIGURE 11.3 A, B, C: Pre-operative MRI for illustrative case 1. Suprasellar, retrochiasmatic lesion, removed via frontolateral approach.
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(B)
(A)
FIGURE 11.4
(C)
A, B, C: Post-operative MRI for illustrative case 1, showing a complete removal of the tumor.
(A)
(B)
(C)
FIGURE 11.5 A, B, C: Pre-operative MRI for illustrative case 2. Retrosellar lesion extending to the posterior fossa, with severe compression of the hypothalamus, the third ventricle, and the brainstem, removed via the transpetrosal approach.
brainstem (Figure 11.5A, B, C). The pre-operative endocrinological evaluation also revealed low levels of cortisol and testosterone. He underwent a complete removal of the lesion through a presigmoidal transpetrosal approach. During the post-operative period the patient experienced transient DI, and transient cranial nerves III and VI palsy, which recovered completely within 3 months. At the last follow-up, 3 years after surgery, the patient was doing well, and was attending college. He had no endocrine or visual deficits and his MRI did not show any recurrence (Figure 11.6A, B).
Illustrative Case 3 This 20-year-old man had undergone removal of a craniopharyngioma at the age of 6 and had been followed by his endocrinologist for hypopituitarism. He presented to the emergency room complaining of near complete loss of vision in the left eye for about 4 days. His MRI showed a recurrent complex suprasellar retrochiasmatic lesion, measuring 17 x 18 x 18 mm, with encasement of the basilar artery (Figure 11.7A, B, C). Because of the
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(A)
FIGURE 11.6
(B)
A, B: Post-operative MRI for illustrative case 2. The tumor was completely removed, no endocrine
deficiency.
(A)
(B)
(C)
FIGURE 11.7 A, B, C: Pre-operative MRI for illustrative case 3. Recurrent complex suprasellar retrochiasmatic lesion, with encasement of the basilar artery. A two-stage surgery was planned, and the tumor was removed via the frontolateral approach first and the tranpetrosal approach in the second stage.
complexity and the extension of the lesion, an operation in two stages was planned. He underwent a frontolateral approach with a partial removal of the lesion first, followed by a transpetrosal approach for removing the residual posterior part of the craniopharyngioma located anterior to the brain stem with encasement of the basilar artery. Post-operatively he manifested hydrocephalus and a lumboperitoneal shunt was placed. At the last followup, 5 years after the operation, the patient was doing well, and functioning normally. He had completed high school, and was seeking employment. He had chronic hypopituitarism and visual deficit in the left eye: he had light perception, but was unable to discern objects with it. His MRI showed a stable small amount of enhancement in the left parasellar region (Figure 11.8A, B).
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(B)
(A)
FIGURE 11.8 A, B: Post-operative MRI for illustrative case 3, showing a near-complete tumor removal, with a stable small amount of enhancement in the left parasellar region.
Illustrative Case 4 This is a 29-year-old woman presenting with progressive vision loss that was greater in the left eye than in the right, and bilateral visual fields cuts. Her MRI showed a suprasellar retrochiasmatic lesion, extending up to the third ventricle (Figure 11.9A, B, C). She underwent an endonasal transsphenoidal approach, with a complete removal of the tumor. Her post-operative course was complicated by a CSF leak requiring a re-exploration, and the placement of a nasal septal flap. At her last follow-up, 16 months after surgery, she was doing very well, not presenting any symptoms. Her visual deficits had completely recovered, she had intact pituitary function, no signs of DI, and she was pregnant. Her MRI did not show any recurrence (Figure 11.10A, B).
(A)
(B)
(C)
FIGURE 11.9 A, B, C: Pre-operative MRI for illustrative case 4. Suprasellar retrochiasmatic lesion, extending up to the third ventricle, removed via transsphenoidal approach.
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(A)
205
(B)
A, B: Post-operative MRI for illustrative case 4. The tumor was completely removed and the pituitary stalk was intact.
FIGURE 11.10
CONCLUSIONS Craniopharyngiomas in adults are complex lesions. The majority of tumors can be removed completely, or nearly completely, with the preservation or the improvement of patients’ vision. The frontolateral, transpetrosal, and endoscopic transsphenoidal are the currently preferred operative approaches. A careful endocrine management is required in both the pre-operative and post-operative phases.
Acknowledgments The illustrations were prepared by Jennifer Pryll, medical illustrator. Doctor Laligam N. Sekhar retains the copyright for the illustrations.
References Chi, J.H., Parsa, A.T., Berger, M.S., Kunwar, S., McDermott, M.W., Oct 2006. Extended bifrontal craniotomy for midline anterior fossa meningiomas: minimization of retraction-related edema and surgical outcomes. Neurosurgery 59 (4 Suppl. 2). ONS426e433; discussion ONS433e424. Gerganov, V., Metwali, H., Samii, A., Fahlbusch, R., Samii, M., Nov 22 2013. Microsurgical resection of extensive craniopharyngiomas using a frontolateral approach: operative technique and outcome. J. Neurosurg.. Gulsen, S., Dinc, A.H., Unal, M., Canturk, N., Altinors, N., Mar 2010. Characterization of the anatomic location of the pituitary stalk and its relationship to the dorsum sellae, tuberculum sellae and chiasmatic cistern. J. Korean. Neurosurg. Soc. 47 (3), 169e173. Khamlichi, A.E., Melhaoui, A., Arkha, Y., Jiddane, M., Gueddari, B.K., 2013. Role of gamma knife radiosurgery in the management of pituitary adenomas and craniopharyngiomas. Acta. Neurochir. Suppl. 116, 49e54. Niranjan, A., Kano, H., Mathieu, D., Kondziolka, D., Flickinger, J.C., Lunsford, L.D., Sep 1 2010. Radiosurgery for craniopharyngioma. Int. J. Radiat. Oncol. Biol. Phys. 78 (1), 64e71. Roth, C.L., 2011. Hypothalamic obesity in patients with craniopharyngioma: profound changes of several weight regulatory circuits. Front. endocrinol. 2, 49. Rushing, E.J.G.F., Paulus, W., Burger, P.C., 2007. Craniopharyngioma. In: Louis, D.N.O.H., Wiestler, O.D., Cavenee, W.K. (Eds.), WHO Classification of Tumours of the Central Nervous System, fourth ed. IARC Press, Lyon, pp. 238e240.
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Sachs, E., 1949. Diagnosis and treatment of brain tumors and care of the neurosurgical patient. C.V. Mosby Company, St. Louis, p 13. Shirane, R., Ching-Chan, S., Kusaka, Y., Jokura, H., Yoshimoto, T., Apr 2002. Surgical outcomes in 31 patients with craniopharyngiomas extending outside the suprasellar cistern: an evaluation of the frontobasal interhemispheric approach. J. Neurosurg. 96 (4), 704e712. van Overbeeke, J., Sekhar, L., Jun 2003. Microanatomy of the blood supply to the optic nerve. Orbit 22 (2), 81e88.
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