Craniopharyngiomas: An Appropriate Surgical Treatment based on Topographical and Pathological Concepts

Abstract

Treatment of craniopharyngiomas (CPs) represents a neurosurgical challenge, the major reason being their close relationship with the hypothalamus and the third ventricle (3V) boundaries. Nevertheless, CPs are generally defined as “suprasellar” lesions, an imprecise and frequently faulty term. Despite being heterogeneous lesions, CPs are actually characterized by repeating pathological patterns which depend on their point of origin along the pituitary-hypothalamic axis. Preoperative understanding of the accurate CP-hypothalamus relation is fundamental for planning proper surgery for each tumor. The two opposing therapeutic strategies usually advocated for CP treatment, radical versus conservative removal, should be replaced by a tailored plan to pursue the maximal tumor resection while minimizing the likelihood of hypothalamic injury in each case. Our topographical scheme, based on the accurate definition of the CP-third ventricle floor relationship, has proven useful to predict the degree of hypothalamic distortion and adherence to the tumor, fundamental information to predict the surgical risk associated with radical tumor removal. Apart from the sellar-suprasellar category of CPs, formed by tumors growing below a non-distorted third ventricle floor (TVF), four major CP topographies can be considered: i) suprasellar-pseudointraventricular CPs, which grow below an intact but upward displaced TVF; ii) suprasellar-secondary intraventricular CPs, which originate below the TVF but break through it and invade the 3V; iii) not-strictly intraventricular or infundibulo-tuberal CPs, which originate within the TVF itself and predominantly expand into the 3V; and iv) strictly intraventricular CPs that wholly develop within the 3V, above an intact TVF. The most extensive and strongest CP-hypothalamic adhesions occur in the secondary intraventricular and infundibulo-tuberal categories. A hypothalamic position around the middle portion of the tumor, an amputated pituitary stalk and an elliptical tumor shape on preoperative MRI are reliable signs to predict a high-risk CP adherence severity level. In these cases a limited removal is strongly advocated.