[The 2013 Sixto Obrador Award. A triple-axis topographical model for surgical planning of craniopharyngiomas. Part II: Anatomical and neuroradiological evidence to define triple-axis topography and its usefulness in predicting individual surgical risk]

Abstract

Introduction and objectives: This study evaluates the pathological and magnetic resonance imaging evidence to define the precise topographical relationships of craniopharyngiomas and to classify these lesions according to the risks of hypothalamic injury associated with their removal.

Material and methods: An extensive, systematic analysis of the topographical classification models used in the surgical series of craniopharyngiomas reported in the literature (n=145 series, 4,588 craniopharyngiomas) was performed. Topographical relationships of well-described operated craniopharyngiomas (n=224 cases) and of non-operated cases reported in autopsies (n=201 cases) were also analysed. Finally, preoperative and postoperative magnetic resonance imaging studies displayed in craniopharyngiomas reports (n=130) were compared to develop a triple-axis model for the topographical classification of these lesions with qualitative information regarding the associated risk of hypothalamic injury.

Results: The 2 major variables with prognostic value to define the topography of a craniopharyngioma are its position relative to the sellar diaphragm and its degree of invasion of the third ventricle floor. A multivariate diagnostic model including 5 variables -patient age, presence of hydrocephalus and/or psychiatric symptoms, the relative position of the hypothalamus and the mammillary body angle- makes it possible to differentiate suprasellar craniopharyngiomas displacing the third ventricle upwards (pseudointraventricular craniopharyngiomas) from either strictly intraventricular craniopharyngiomas or lesions developing primarily within the third ventricle floor (infundibulo-tuberal or not strictly intraventricular craniopharyngiomas).

Conclusions: A triple-axis topographical model for craniopharyngiomas that includes the degree of hypothalamus invasion is useful in planning the surgical approach and degree of resection. Infundibulo-tuberal craniopharyngiomas represent 42% of all cases. These lesions typically show tight, circumferential adhesion to the third ventricle floor, with their removal being associated with a 50% risk of hypothalamic injury. The endoscopically-assisted extended transsphenoidal approach provides a proper view to assess the degree and extension of craniopharyngioma adherence to the hypothalamus.

Keywords: Craneofaringioma; Craniopharyngioma; Hipotálamo; Hipófisis; Hypophysis; Hypothalamus; Mammillary body angle; Tercer ventrículo; Third ventricle; Tuber cinereum; Ángulo mamilar.