Crniopharyngiomas

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Symptoms and Signs

Although lesions that expand in the suprasellar region have a high potential for producing neurological deficits, there may be some variation in presenting complaints, and adults and children have dissimilar clinical syndromes. These differences are summarized in Tables-1 and 2. Since craniopharyngiomas are slow­growing, extra-axial tumors, they may grow quite large before causing symptoms, especially in children. Many of these tumors in children obstruct the flow of cerebrospinal fluid (CSF) and present with increased intracranial pressure. In addition, children will tolerate a surprising degree of visual loss without complaint and may continue school and watch television without arousing the suspicions of parents or teachers despite severe deficits (in one case, complete visual loss in one eye and a major field cut in the other).

Adults are much more sensitive to visual impairment, and it is almost uniformly a complaint of adult patients. A notable exception are patients with purely intrasellar lesions. In institutions treating large numbers of women with complaints of amenorrhea or infertility, a higher proportion of intrasellar tumors is now found than was reported in series of even a decade ago.

Psychiatric symptoms are difficult to diagnose in children, and most examples are found in adults, usually in association with hydrocephalus. Decreases in mentation (especially memory), apathy, incontinence, depression, and hypersomnia may be noted. Long-standing mentation deficits or depression are associated with a poor prognosis. Kahn and coworkers found the marked mental changes of Korsakoff's syndrome in 3 of 12 adult patients

Diagnostic Procedures
Almost all craniopharyngiomas have a common origin from cells in the infundibular region. Despite this common site of origin, the growth pattern of the tumor varies enormously. To select the proper operative approach and identify tumors that will require staged operations, it is preferable to have complete radiologic tumor visualization in three planes. Both computed tomography (CT) and magnetic resonance imaging (MRI) are used in the evaluation of these tumors. Both types of scanning will demonstrate the mass of the tumor, outline the ventricular system. and show where the tumor abuts CSF spaces. Enhancement with an appropriate contrast agent will often bring out the solid portions of the tumor and allow better definition of cyst walls. The use of various MRI sequences often allows correct definition of cystic portions of craniopharyngiomas, which may appear solid on CT scanning. The density of cysts varies widely, depending on the content of protein and blood and the presence of keratin and calcium salts.

Sagittal MRI views have proved most useful. They show the relationship between the tumor and the optic nerves and chiasm, pituitary stalk, and basilar artery. In particular. tumors that look intraventricular on axial CT scans may be shown by the sagittal MRI view to abut the basal cisterns. Approaching the tumor through the basal cisterns may allow removal by entirely extra­axial pathways. Although MRI has been the most useful modality for defining the geometry and extension of craniopharyngiomas, it may fail to reveal solid, calcified portions of the tumor. Similarly. small calcifications that remain after surgery may not be appreciated on MR scans. We have found a combination of MRI and CT to be useful preoperatively and postoperatively.

Some authors have advocated preoperative angiography in the diagnostic workup of these tumors. However. the relationship between the tumor wall and the major vessels of the circle of Willis can be defined on MR scans, and MR angiography can be used as well. Scanning techniques have made preoperative angiography unnecessary in our practice for more than tow decades. Vessels that directly supply the craniopharyngioma are quite small and difficult to demonstrate on angiography. and even the perforating vessels that must be saved are not well seen.

Changes in the structure in the bone at the base of the skull may be identified by CT or plain radiograph and are characteristic in craniopharyngiomas. Two-thirds of the adults and almost all of the children will show bone changes on these studies. Half of all patients have an enlarged sella. Tumors with a suprasellar component may cause erosion of the dorsum sellae and anterior clinoids. Tumor calcification is found in approximately 85 percent of childhood tumors and 40 percent of those in adults.

Endocrine assessment is usually performed preoperatively. These tests are not diagnostic but indicate those patients at higher risk endocrinologically. Both hypoadrenalism and hypothyroidism may contribute to poor intra- or postoperative results. Hypoadrenalism is correctable and is adequately treated by the high dosages of steroid used in contemporary cranial surgery. Hypothyroidism takes longer to correct and correction should be attempted preoperatively if the patient shows clinical manifestations of decreased thyroid function or has mentation deficits and if the need for surgical intervention is not pressing. If endocrine results are not available and if there is an urgent need to decrease intracranial pressure, CSF shunting or external drainage may be employed. and the major operation deferred.