As seen microscopically, most craniopharyngiomas have an outer layer of tall columnar epithelial cells that migrate inward into polygonal epithelial cells of varying sizes, with a central meshwork of epithelial cells (Figure 237-1). These epithelia are scaffolded by a mesodermal connective tissue stroma. It has been proposed that epithelial cell degeneration causes cellular hyalinosis and deposition of keratin-like material [4, 17, 18]. The stroma in the center of the tumor can also degenerate and form a cystic portion [4]. The collagenous basement membrane forms the border between the tumor and the surrounding meninges and brain tissue [18]. The cystic wall can be thin and transparent or thicker and can sometimes become rigid due to calcium salt deposits. Calcifications can be found microscopically in close to half of adults and almost all children with craniopharyngiomas [19, 20].
Occasionally, some craniopharyngiomas have been reported in the literature as fast-growing and prone to recurrence, but they are not usually considered to be malignant, and Matson and Crigler [21] specifically noted that craniopharyngiomas do not invade brain tissue. Electron microscopic studies of some aggressive craniopharyngiomas have been reported to reveal certain mesenchymal features of the tumors [22], but tissue culture studies revealed that mitotic cell division was rare in these tumors and that there was a clear tendency for cyst formation [23]. A recently reported case of tumor transformation from a typical craniopharyngioma to a squamous cell carcinoma deserves still to be confirmed, as the tumor was treated with three courses of radiation therapy [24].
Craniopharyngiomas often cause a strong glial response in the surrounding brain tissue [25]. The glial reaction is more pronounced around small papillary craniopharyngiomas that protrude into the subhypothalamus (Figure 237-2). Some scholars believe that because of the presence of a dense glial reaction zone, surgical traction of the tumor can damage the hypothalamus and thus prevent total tumor resection [26]. However, Sweet [27] suggested that this “glial envelope” provides an interface that allows safe separation of the craniopharyngioma from the surrounding brain tissue during surgery. In addition, several autopsies have revealed only slight adhesions at the level of the gray nodes [19, 28].
Craniopharyngiomas are often closely adherent to the major arteries at the base of the brain [29]. In the literature, six of 23 children with craniopharyngioma could not be completely resected due to adhesions to the internal carotid artery [28, 31]. A summary of pediatric patients with craniopharyngioma that could not be completely resected revealed that far more residual tumors adhered to the major arteries of the Ring of Willis than to the hypothalamus and optic cross (Figure 237-3) [31, 32]. It is possible that the adhesions formed due to interstitial reaction between the tumor and the vessel wall are more rigid and tight compared to the glial reaction [33].
The blood supply to suprasellar craniopharyngioma is mainly from small supply arteries of the anterior circulation [19]. There is also thought to be a direct blood supply from branches of the internal carotid artery, the posterior communicating artery. However, craniopharyngiomas do not receive blood from the posterior cerebral artery and the bifurcation of the basilar artery unless the tumor is close to the base of the third ventricle supplied by these vessels [19]. The blood supply to the intersaddle tumor comes from the small penetrating artery of the internal carotid artery in the cavernous sinus.
Morbidity
Craniopharyngiomas account for 2.5-4% of all brain tumors [34-35] and can develop at any age, preferably in children aged 5-15 years, but pediatric craniopharyngiomas account for less than half of all craniopharyngiomas, and in one large case report, the oldest age of the patient operated on was 71 years [20]. Figure 237-4 shows the age distribution of a group of 109 patients reported in the literature. A few reported incidence rates were higher in males than females, and in pediatric patients, many reports showed no gender differences in incidence [20, 28, 32, 36] .Maston [37] counted a large group of intracranial tumors in children and found that craniopharyngiomas accounted for 9% of cases and their incidence was first among neoplasms of non-glial origin. Despite the high proportion of craniopharyngiomas in childhood brain tumors, 60% of patients were older than 16 years of age at presentation. The incidence of craniopharyngioma in the population is low, with a documented incidence of 0.13 per 100,000. There are approximately 338 new cases per year in the United States, including 96 pediatric patients 14 years of age or younger [99].
Signs and symptoms
Although patients may not be first seen for endocrine dysfunction, the main signs and symptoms in patients with craniopharyngioma are the various clinical manifestations caused by endocrine dysfunction. Approximately 93% of pediatric patients present with growth retardation, while adults present with sexual dysfunction or menstrual cycle disorders (88% of male patients present with decreased libido and 82% of female patients present with primary or secondary amenorrhea) [40, 41].
Craniopharyngiomas are slow-growing extra-axial tumors that are often very large by the time they become symptomatic, especially in pediatric patients. Children with severe visual impairment often fail to notice it and continue to attend school or watch television without attracting the attention of parents and teachers [32]. Adult patients are more sensitive to visual impairment, with approximately 90% complaining of vision loss.
About half of the patients present with headache, often due to hydrocephalus caused by the tumor. In pediatric patients, tumors often block cerebrospinal fluid pathways, causing signs and symptoms of increased intracranial pressure. In adults, giant tumors can cause psychosomatic symptoms or memory loss, which may or may not cause hydrocephalus. These patients may present with emotional indifference, poor self-control (incontinence), depression, and lethargy. Giant tumors may also grow posteriorly into the posterior cranial fossa, and three cases of posterior cranial fossa tumors reported in the literature presented with hearing loss [43].
Diagnostic imaging
Almost all craniopharyngiomas originate from remnant cells of the pituitary stalk and can be either supra- or subsaddle diaphragmic. Despite the same origin, the structure, morphology and growth type of the tumor vary considerably.Fahlbusch and colleagues [41] emphasized the importance of knowing the anatomical features of the tumor in terms of 1) whether the tumor is located under the saddle diaphragm; 2) whether the tumor is located on the saddle diaphragm and simply elevates the hypothalamus and third ventricle; or 3) whether the tumor penetrates the floor of the third ventricle and enters the third ventricle.
Electron computed tomography (CT) and magnetic resonance imaging (MRI) are valuable in showing the morphology of the tumor, its relationship to the ventricular system and the major intracranial arteries. enhanced MRI scans are more sensitive and can show mildly enhanced cystic walls and substantial portions of the tumor. On CT or MRI scans, the cystic portion of craniopharyngioma may appear as hyaline or dense changes due to differences in the protein composition of the cyst fluid and suspended calcium salts.
Sagittal MRI clearly shows the relationship between the tumor and the optic nerve and optic cross. MRI T2-weighted images help to distinguish the relationship between the suprasellar tumor and the anterior portion of the visual pathway. Tumors located within the triple ventricle on CT axial scans may actually be located within the suprasellar pool, and if the base of these tumors can be identified and exposed on the basal pool, the tumor can be removed through a purely extra-medial approach. (Figure 237-6)
CT often clearly demonstrates the calcified portion of the tumor, as well as the anatomic changes in the bone of the skull base due to tumor compression, and Kucharczyk and Montanera [45] showed that MRI scans alone can also clearly demonstrate the solid and calcified portions of craniopharyngiomas. CT or MRI scans are more likely to show the main arteries on the surface of the tumor, and patients do not need cerebral angiography for surgery.
Endocrine function test
Pituitary function tests are usually performed preoperatively. Poor intraoperative or perioperative outcomes are often due to adrenal and thyroid hypofunction [32]. Correction of hypoadrenalism with high-dose steroids may prevent intraoperative brain edema due to straining. Hypothyroidism is more difficult to correct and requires a longer period of treatment. Along with attention to preoperative diagnostic endocrine function tests, additional endocrine function tests must be performed when various postoperative hormone supplementation is discontinued. Postoperative follow-up in endocrinology, neuro-ophthalmology, and neuropsychology is also necessary [31].
Surgical treatment
Management of hydrocephalus and tumor macrocysts
Many patients with craniopharyngioma often present with a variety of clinical symptoms due to hydrocephalus, which is the most common clinical type in pediatric patients. In most cases, the cystic portion of the tumor is large in size and the treatment must first deal with the occupying effect caused by the tumor or cyst [46]. When the main manifestation is a variety of symptoms caused by hydrocephalus, a shunt can be performed first, and when the tumor blocks the bilateral Monro foramen, a bilateral ventricular placement is required, which is then connected to a single-tube shunt system (Figure 237-7). When a single large cyst is present within the tumor, it is valuable to drain the cystic portion prior to surgical resection to reduce the size of the tumor.
Continuous ventricular drainage over a period of time to relieve hydrocephalus and cystic partial drainage of the tumor, resulting in lower intracranial pressure, is preferable to a single puncture aspiration. Continuous drainage in patients with hydrocephalus can both lower intracranial pressure and control drainage flow. Similarly, continuous external drainage with a tumor cystic internal tube is beneficial to prevent sudden drop in intracranial pressure.
Tumor resection
There are various surgical approaches for craniopharyngioma. The choice of surgical approach should be based on the size of the tumor, the growth site, the degree of tumor calcification, and the easy access to cerebrospinal fluid pathways. Table 237-1 lists the various accesses available, from which the principles of various accesses can be seen. In general, the transmedial approach is preferred over the transmedial approach, and the unilateral approach is preferred over the bilateral approach that requires elevation of both frontal lobes, and except for a few cases, the tumor site can be reached directly without cutting through functional neural tissue.
The right inferior frontal approach requires only a slight stretching of the non-dominant hemisphere and is convenient for right-handed neurosurgeons. When the tumor expands mainly to the left front or grows to the left middle cranial fossa, the left or bilateral inferior frontal approach is required. In most cases, a coronal skin incision is used, and the bone flap should be as low as possible to the base of the anterior cranial fossa, usually avoiding the frontal sinus. When the posterior saddle area needs to be fully exposed, the craniotomy should be wide, including the anterior temporal area, and the lateral part of the pterygoid crest should be abraded as much as possible. The inferior frontal approach can be subdivided into several approaches (Figure 237-8): access to the gap between the optic nerves through the inferior optic cross or by grinding away the saddle nodes; opening the end plate to expose access to the third ventricle; and access to the tumor through the medial or lateral internal carotid artery to expose the tumor in the lateral part of the optic nerve and optic tract. The neurosurgeon should consider all possible approaches and choose the one that provides the greatest exposure of the tumor surface. Tumors that fill the trigeminal ventricles can push the optic cross anteriorly and squeeze the bundle laterally, and displacement of the visual organs can cause anteriorization of the optic cross and narrowing of the surgical separation space [33] [46]. During surgery, the arachnoid pool is separated along the edge of the pterygoid crest, the optic nerve, and the tumor surface to expose the tumor, and attention is paid to identifying the arachnoid membrane with a double (or multiple) layer structure and recognizing the arachnoid plane extending from the tumor surface (Figure 237-9). When using bipolar electrocoagulation for electrocautery, be careful not to adhere the arachnoid membrane on the tumor surface to the tumor envelope, as preserving the arachnoid plane facilitates safe total resection of the tumor, and the correct plane of separation is located between the arachnoid and tumor envelope, not within the arachnoid pool.
After tumor exposure, including scans suggestive of solid tumors, all tumor punctures should be performed first. Many tumors that scan as dense or solid contain a cystic component, and puncture can provide more room for surgical separation even if only a few milliliters of cystic fluid can be aspirated. For tumors with large cysts, it is sufficient to start with only a partial aspiration of the cystic fluid because the cyst containing the fluid provides a tense interface that facilitates separation of the tumor envelope from the arachnoid membrane. If too much cystic fluid is extracted at the beginning, the envelope will be too long and the separation along the tumor surface will be more difficult.
After most of the tumor surface is separated, the tumor can be aspirated and decompressed within the tumor. After decompression of the tumor, the artery supplying the tumor can be cut off by electrocoagulation and the arterial anastomosis around the median elevation can be carefully protected. The posterior or upward extension of the tumor into the triple ventricle often lacks significant arterial blood supply and does not adhere tightly to the surrounding area. During secondary surgery, tumors located below the basilar artery and posterior cerebral artery system often adhere closely to the surrounding area and should be removed with special care. The part of the tumor envelope that enters the visual field can be removed, but care should be taken not to lose the position of the traction, especially when a shunt has been placed. Once the traction of the intraventricular part of the tumor is released, the tumor will quickly retract and leave the visual field, making it difficult to retrieve the tumor. In pediatric patients, the calcified portion tends to be located at the base of the tumor, usually below the optic cross and optic nerve, and the calcified foci often need to be fragmented and then removed through the optic apparatus. Tumors remaining in the optic apparatus and below the hypothalamus need to be removed with a sharp separation. Finally, the use of a small angled dental microscope to examine the optic cross and the median eminence for residual tumor has been shown to be very useful in examining the tumor with an endoscope rather than with a microscope.
It has been reported in the literature that some small craniopharyngiomas can be located throughout the saddle [33, 49], and on CT scan the tumor appears as a clear area within the saddle, which may be misdiagnosed as a pituitary prolactin adenoma in female patients; these tumors are easily resected by transsphenoidal approach and the tumor envelope is easily distinguished. Some tumors with considerable suprasellar extension are also easily resected through the transsphenoidal approach as long as the tumor only elevates the saddle diaphragm at the upper pole, while the entire tumor remains subsaddle diaphragm [49].
Larger tumors that penetrate the saddle diaphragm, especially those with significant calcification, are more difficult to resect with a transsphenoidal approach even if the saddle is extensively disrupted, and Laws and co-workers have reported [50] a case of bilateral injury to the internal carotid arteries during resection of a very large, calcified saddle tumor. Large cystic tumors, including those with large suprasellar extensions, can still be resected by a transsphenoidal approach (Figure 237-10A and B). When the tumor causes extensive destruction of the pterygoid saddle, the saddle must be repaired with fat after tumor removal to prevent syndrome of chiasmatic prolapse (Figure 237-10C). (Figure 237-10C).
Samii and Bini recommended the introduction of a bifrontal approach for the removal of craniopharyngioma [48]. Surgery using this approach requires careful separation of the bilateral olfactory bundles back to the bilateral olfactory triangle. This approach provides good exposure of the tumor bilaterally and also allows adequate exposure of the end plate for accurate localization of the midline position.Samii suggested me to use this approach and subsequently applied it to 6 consecutive cases where the operation had to be performed around the bilateral olfactory and bilateral optic nerves, which was a bit tricky to perform and in 2 cases caused rupture of the olfactory bundle on one side due to excessive stretching. Opening the end plate is an important step to fully expose the resected third ventricle and many of the tumors that will elevate the floor of the third ventricle. Gentle pressure on the base of the third ventricle facilitates the operator’s ability to find residual tumor at the base of the third ventricle where the surface appears to lie in the suprasellar pool. The bifrontal approach allows the operator to accurately determine the midline location, whereas other lateral approaches often interfere with the operator’s judgment of the midline, the inferior frontal approach on one side has minimal effect, and the pterygoid point approach makes localization and direct visualization within the tricompartment difficult.
It has been described that the tumor can be removed through temporal lobe or inferior temporal approach. The literature reports 20 patients with craniopharyngioma in whom the anterior temporal lobe was surgically resected first in an attempt to radically remove the tumor [29]. Although only one death due to surgery was reported in this report, two other cases died due to pneumonia caused by varying degrees of postoperative coma.
Tumors within the third ventricle are often resected using a transmedial approach, either a transcallosal approach or a transfrontal-lateral ventricular approach, and Yasargil et al [51] noted that a transmedial approach can also be combined with a subfrontal approach. For this type of tumor, a more adequate exposure of the third ventricle is required than a simple approach through the interventricular foramen. The following methods of access to the third ventricle are available: (1) separation of the F fornix on one side; (2) separation of a vein adjacent to the interventricular foramen; (3) subchoroidal access via the choroid plexus; and (4) separation of the internal cerebral veins [46, 52, 53].
Sometimes staged surgery is necessary for total removal of the tumor. Usually, a transcranial procedure is used to remove the suprasellar portion of the tumor first, and a transsphenoidal sinus approach is used in the second stage to remove the intersellar portion of the tumor. [33, 36, 47]. Some tumors grow toward the middle and posterior cranial fossa and cannot be removed through the inferior frontal approach; in the second stage, the tumor must be removed using a trans-temporal, trans-inferior temporal, or using a posterior cranial fossa approach.
Pituitary stalk preservation
Radical resection of craniopharyngiomas while preserving the pituitary stalk has become possible with the application of advanced direct microscopy [33, 47, 48]. When the pituitary stalk is injured, the remnant of the pituitary stalk from the median eminence to the pituitary gland can serve as a stroma on which the pituitary portal system will repair itself.
Identification of the pituitary stalk is the basis of pituitary stalk preservation. The pituitary stalk can be displaced to various locations on the tumor surface, but it is often found where it crosses the saddle diaphragm to reach the pituitary gland. Another characteristic of identifying the pituitary stalk is the striated shape formed by the long portal veins on the surface of the pituitary stalk. Even when the pituitary stalk is severely displaced, these veins maintain their original parallel alignment, and this striated shape is more unique among the structures on the saddle.
Cyst puncture
Some scholars have advocated that cystic craniopharyngioma before radiation therapy and cystic tumors that recur and are treated again after isotope implantation should be treated by first puncturing and aspirating the cystic fluid [56-58]. For recurrent cystic tumors in children, some have treated them with drainage methods first and then treated with radiation after the child’s growth is complete. The literature has reported a case of a patient with cystic tumor in which the cystic fluid automatically flowed out of the nasopharynx for 30 years, and the patient remained in good condition throughout the process [59]. It has also been recommended that a drainage tube be placed into the tumor capsule and then connected to an Ommaya pump so that the capsule fluid can be repeatedly pumped out [46, 60], but there is a risk that this treatment will be overused in patients. It rarely works in those whose cyst wall has been partially resected before placement of the drain, because the cyst wall repair process often rejects the drain outside the cyst (Figure 237-12). Even if the drainage tube is placed after puncture with a puncture needle, it can quickly become obstructed by the formation of a fibrous sphincter covering it.
Postoperative monitoring
Patients with craniopharyngioma often receive high doses of highly potent anabolic corticosteroids to combat cerebral edema after craniotomy, and these anabolic steroids have the effect of the mildly saline corticosteroid hydrocortisone acetate; as these anabolic steroids are tapered, physiologic doses of hydrocortisone need to be applied instead of therapy. Patients with craniopharyngioma often have hyperalgesia, and patients must be given supplemental corticosteroids in cases of infection, stress, and fever. One death has been reported in a patient after craniopharyngioma resection during a metyrapone test [61].
Urolithiasis is almost always present after total or subtotal craniopharyngioma resection. Treatment starts with fluid replacement, and short-acting angiotensin needs to be applied when the patient develops irritable thirst or frequent urination, or when the disease progresses to hypernatremia. It should be understood that the release of antidiuretic hormone (ADH) after pituitary stalk damage is triphasic [62]. Initially, due to pituitary stalk damage, ADH secretion ceases, and then the axon terminals in the posterior pituitary degenerate and release ADH in higher amounts than physiologically required, which often occurs 48-96 hours after pituitary stalk injury. If a patient is given a long-acting antidiuretic agent, there is a risk of low renal filtration when endogenous ADH is secreted. When ADH is depleted at the end of the degenerated axon, uremia reappears. Treatment with intravenous acetic acid, oral tablets, and intranasal injection can be applied. Regular careful observation of urine specific gravity, body fluid intake and output, and blood electrolytes is necessary for successful treatment of post-surgical uremia.
Patients with uremia lacking a sense of thirst are more difficult to treat, a condition often seen in the presence of damage to the anterior hypothalamic osmolarity receptors and pituitary stalk dissection [54]. The lack of thirst is detrimental to the regulation of the patient’s blood electrolyte levels and can present with various complications arising from hypernatremia. Other symptoms of hypothalamic insufficiency caused after craniopharyngioma surgery include imbalance in caloric balance, altered arousal state and emotional behavior, and memory impairment.
Death after craniopharyngioma surgery is often due to hypothalamic injury and is clinically manifested by hyperthermia and lethargy. One patient had a fluctuating state of consciousness for as long as 15 months after surgery and finally died of pneumonia [29].
Conclusion
Most neurosurgeons consider total surgical removal of craniopharyngioma to be the most desirable outcome and to provide the best chance of cure for the patient [32, 47, 48, 51, 63]. The treatment strategy of the neurosurgeon depends on whether it is worthwhile to attempt total resection of the tumor at the risk of surgical death and functional impairment of the patient. It has been documented that total resection of the tumor as much as possible leads to a very satisfactory outcome, with some of them reporting low complication rates and no surgical deaths [47, 48, 51, 64, 65]. The mortality rate after radical resection of craniopharyngioma varies from one report to another, with a combined mortality rate of 1-10% reported in a large variety of cases. Most physicians consider a surgical mortality rate of more than 35% unacceptable in the modern era of neurosurgery, even for surgical treatment of giant tumors [66]. Some scholars also believe that craniopharyngiomas can be treated as malignant tumors due to their deep location and diverse growth types, and there is no need to overemphasize surgical radical resection [67].
Some craniopharyngiomas cannot be completely resected radically, often due to the close adhesion of the tumor to the surrounding important nerve and vascular structures, which prevents the safe resection of the tumor, and the residual tumor must be treated by other methods; some of them, which the surgeon thinks have been completely resected, can still be found to have residual tumor on immediate postoperative review or on imaging review after a period of time, and these so-called “accidental residual These so-called “accidental residual” tumors can be treated immediately by surgery or radiation therapy, or further treated after observing their growth.
Available data show that tumors treated by subtotal or partial resection without other methods are less effective and often recur after a period of time [32, 68], so that surviving patients are at risk of recurrence [69]. sung and his co-workers [20] noted that less than 10% of patients with craniopharyngioma treated by subtotal resection alone do not recur within 10 years after surgery. Some craniopharyngiomas can remain quiescent for years after partial resection, and some patients can live completely asymptomatic after partial resection [19, 40]; these rare cases may also be overemphasized, and in fact, most subtotal resected tumors recur within 3 years after surgery. Recurrence occurs later in radically total resected tumors than in those with partial resection alone [32, 68]. Patients with subtotal resection will likely have to take further treatment, either with radiation therapy or reoperation.
Radiation therapy
More than 70 years ago, Carpenter et al [57] reported a small group of patients with craniopharyngioma who showed significant improvement after radiation therapy, and they concluded that although the tumor was not destroyed by X-rays, the cells that had the ability to secrete and form cysts could be killed [70]. Subsequently, there have been doubts about the ability of radiation therapy to destroy craniopharyngioma epithelial cells [28].In the 1960s, Kramer et al [71, 72] reported good results after subtotal resection plus ultra-high voltage radiation therapy. Many subsequent studies have shown that radiation therapy improves patient survival and prolongs tumor recurrence [20, 65, 70, 73]. Patients treated with surgery plus radiotherapy have higher survival rates than those treated with surgery alone and significantly increase recurrence-free survival [20]. The results of subtotal resection plus radiotherapy have been reported to be satisfactory, as Baskin and Wilson [40] reported that in 74 cases treated with this method, 91% of patients achieved symptomatic relief and the operative mortality rate was 3%, and Shapiro et al [60] reported a lower recurrence rate in patients treated with subtotal resection plus radiotherapy than in patients treated with biopsy and cyst drainage followed by radiation. Recently, Merchant et al [74] also advocated conservative tumor decompression followed by radiation therapy.
However, the risks of radiation therapy cannot be ignored, and complications such as radiation brain necrosis, optic neuritis, endocrine hypofunction and dementia have been reported in the literature [32]. Radiotherapy may also induce the development of tumors, including meningiomas, various sarcomas, and gliomas (Figures 237-13 and 237-14). In pediatric patients, radiotherapy can cause severe intellectual impairment [75]. Therefore, there is a preference for delaying radiotherapy in pediatric patients at our institute. It is not clear at what age the damage of radiation therapy to the developing brain stops. Complications of radical resection of the tumor have also been reported to impair intelligence [75].
Reports of delayed neuropsychological and cognitive impairment due to craniopharyngioma surgery and radiation therapy are scarce and differ. In one report of 12 pediatric patients with craniopharyngioma after radical resection, no cognitive or short-term memory impairment was found, except for mild disorientation impairment in three cases [76]. In another group of prospective studies, no neuropsychological impairment was found in 13 patients with craniopharyngioma after surgery, and quality of life evaluations were significantly improved [25].
More recently, a literature analysis of 30 patients treated between 1984 and 1997 yielded different conclusions. In this group, 15 of the patients treated early attempted surgical resection of the tumor, of which 8 were given postoperative radiation therapy, while the next patients were given only “limited” surgical resection and all were treated with postoperative radiation therapy. The “limited” surgery group had a more pronounced reduction in intelligence scores (IQ) than the early surgery group, but fewer endocrine and neurological complications [74]. In a subsequent report, these authors treated all patients after 1997 with radiation therapy and scored the neuropsychological quantification of radiation therapy-induced damage to the central nervous system, and they concluded that there was no decrease in IQ scores on all items after radiation therapy in children with cerebral hemisphere or posterior cranial fossa tumors, while there was a significant decrease in midline tumors, especially in patients with craniopharyngioma, where the mean IQ score before radiation therapy was 91 and 30 months after treatment was 91, and the mean value decreased to 78 30 months after treatment [77].
A second surgery after tumor recurrence or radiotherapy is more difficult than the first surgery, and even physicians who advocate radical resection for the first surgery consider that the risk of reoperation is significantly higher. There is no doubt that localization of the arachnoid border and scar separation become more difficult during surgery for recurrent or previously radiated tumors, but it is my experience that these conditions do not prevent successful resection of the tumor (Figure 237-15).
Doctors who want to routinely perform total resection of craniopharyngiomas do not always remove the tumor completely [30, 31, 68]. Even when experienced surgeons use microsurgical techniques for total resection of tumors, there is still a certain rate of tumor recurrence, and Amacher [63] reviewed several reports and found tumor recurrence in 17 of 92 cases of total resection. Routine application of advanced imaging scans can detect most, if not all, residual tumor fragments, which helps to reduce the “false cure” rate. Given the tendency of tumors to recur, many scholars do not use the term “resection” of tumors, but instead use the term “radical resection”, but this term cannot be used for cases with large residual tumors.
Stereotactic Radiosurgery
A few small case studies have reported the use of Ý knife or stereotactic linear gas pedal for craniopharyngioma [78-80]. Stereotactic radiosurgery and endovenous radiotherapy or chemotherapy should still be considered scientific in nature [81]. more than 10 years ago, Lunsford [82] found that the first patients treated with stereotactic radiosurgery could develop complications of sudden visual field damage, and therefore recommended that the target should be 3-5 mm from the visual access.
In 31 cases reported by Chung et al [79], who extended radiotherapy to 9 cm3, 10% of the tumors had cystic partial enlargement and 13% tumor regrowth within 3 years after treatment, and another patient had partial visual field loss.Chiou et al [78] treated 10 cases using a median marginal dose of 19.4 Gy and a visual organ dose control of less than 8 Gy, and six cases had visual field defects after treatment with improved and 2 cases required further radiosurgery, but 1 case showed visual loss after treatment to complete loss of vision at 9 months.
Intracapsular radiotherapy or chemotherapy
More experience has been gained in the treatment of craniopharyngioma with cystic portion placement of radionuclides [56, 58, 83, 84]. In all data, knowledge of the volume size of the cystic part of the tumor is the basis for calculating the dose of radioactive material to be injected into the capsule and is an important factor in determining the minimum dose that will act on the cystic wall of the tumor [85].Leksell [86] suggested that a dose of 100 Gy acting on the surface of the cyst will cause the cystic part to atrophy. However, when the cyst wall is thin, this dose will penetrate the cyst wall into the surrounding brain tissue [28]. Some scholars also advocate a cyst wall dose of 200 Gy [56, 58]. Commonly used radionuclides are P32, 198Au, 91Y. Intracavitary radionuclide therapy is limited to craniopharyngiomas containing large cysts and is not suitable for solid tumors and tumors with thick or calcified cyst walls. After treatment, the cyst usually does not change significantly in the early stages, but it shrinks in the following weeks or months [58]. Usually the cyst is intubated and then connected to an external pump, but the use of stereotactic subintubation or direct placement remains a matter of opinion. Some centers use intracavitary radionuclide therapy for the first treatment, but some centers use it only for recurrent cystic tumors [56, 58]. A serious complication caused by radiotherapy has been reported in the literature as severe vision loss due to irradiation around the visual pathway [87]. It is more difficult to evaluate the value of this treatment; for example, in a recently reported group of six patients treated with intracavitary 90Y, with a mean follow-up of 3.5 years, the vast majority of cysts did not require further puncture to remove the cyst fluid after isotope implantation, but there were two deaths, at least one of which was due to tumor enlargement [88].
Bleomycin is a chemotherapeutic agent for the treatment of epithelial tumors and this effect has been applied in tissue culture studies of craniopharyngioma (Fahlbusch et al. citing Kubo and colleagues [47]) Broggi et al [89] reported intracapsular injection of bleomycin into 18 cystic tumors under stereotaxic fixation and 13 cases of cyst shrinkage. The available data suggest first treatment with bleomycin 2-5 mg three times a week for 3-5 weeks [90].Mottolese et al [91] reported 24 cases treated with intracapsular bleomycin alone and 70% of the tumors were in a stable state.
Bleomycin has some toxicity and a watertightness test should be performed prior to injection. Despite careful treatment, one-third of patients may experience transient fever, nausea, and vomiting. Other side effects that have been reported include blindness, drowsiness, and fatal mesencephalic damage.