Craniopharyngioma adherence: a reappraisal of the evidence.

Craniopharyngioma (CP) adherence represents a most baffling problem for the neurosurgeon. The highest priority of current surgical treatment is to maximize tumor removal without compromising the patients' long-term functional outcome. Surgical damage to the hypothalamus may be avoided or at least ameliorated with a precise knowledge regarding the type of adherence for each case. This article presents a comprehensive review of the pathological, surgical, and radiological sources of evidence supporting that CP adherence, despite being heterogenous, is characterized by repeating patterns. The key underlying factors of CP adherence are also discussed. Three components define the type of adherence for each case: (i) the intracranial structures attached to the tumor, (ii) the adherence morphology, and (iii) the adhesion strength. Combination of these three components gives rise to five hierarchical levels of increased risk of hypothalamic injury during tumor removal. Tumor topography has been identified as the major predictor of the type of CP adherence. The most extensive and strongest adhesions to the hypothalamus occur in CPs originated in the suprasellar cistern that secondarily invade the third ventricle (secondary intraventricular CPs) and in those originated within the third ventricle floor itself (not-strictly intraventricular CPs). Three findings observed on preoperative conventional MRI scans have proven to be reliable predictors of adherence severity. A position of the hypothalamus around the middle portion of the tumor, an amputated pituitary stalk, and an elliptical tumor shape points to the severe and critical risk levels, and in those cases, a safer limited removal is strongly recommended.