Displacement of mammillary bodies by craniopharyngiomas involving the third ventricle: surgical-MRI correlation and use in topographical diagnosis

Abstract

Object Accurate diagnosis of the topographical relationships of craniopharyngiomas (CPs) involving the third ventricle and/or hypothalamus remains a challenging issue that critically influences the prediction of risks associated with their radical surgical removal. This study evaluates the diagnostic accuracy of MRI to define the precise topographical relationships between intraventricular CPs, the third ventricle, and the hypothalamus. Methods An extensive retrospective review of well-described CPs reported in the MRI era between 1990 and 2009 yielded 875 lesions largely or wholly involving the third ventricle. Craniopharyngiomas with midsagittal and coronal preoperative and postoperative MRI studies, in addition to detailed descriptions of clinical and surgical findings, were selected from this database (n = 130). The position of the CP and the morphological distortions caused by the tumor on the sella turcica, suprasellar cistern, optic chiasm, pituitary stalk, and third ventricle floor, including the infundibulum, tuber cinereum, and mammillary bodies (MBs), were analyzed on both preoperative and postoperative MRI studies. These changes were correlated with the definitive CP topography and type of third ventricle involvement by the lesion, as confirmed surgically. Results The mammillary body angle (MBA) is the angle formed by the intersection of a plane tangential to the base of the MBs and a plane parallel to the floor of the fourth ventricle in midsagittal MRI studies. Measurement of the MBA represented a reliable neuroradiological sign that could be used to discriminate the type of intraventricular involvement by the CP in 83% of cases in this series (n = 109). An acute MBA (< 60°) was indicative of a primary tuberal-intraventricular topography, whereas an obtuse MBA (> 90°) denoted a primary suprasellar CP position, causing either an invagination of the third ventricle (pseudointraventricular lesion) or its invasion (secondarily intraventricular lesion; p < 0.01). A multivariate model including a combination of 5 variables (the MBA, position of the hypothalamus, presence of hydrocephalus, psychiatric symptoms, and patient age) allowed an accurate definition of the CP topography preoperatively in 74%–90% of lesions, depending on the specific type of relationship between the tumor and third ventricle. Conclusions The type of mammillary body displacement caused by CPs represents a valuable clue for ascertaining the topographical relationships between these lesions and the third ventricle on preoperative MRI studies. The MBA provides a useful sign to preoperatively differentiate a primary intraventricular CP originating at the infundibulotuberal area from a primary suprasellar CP, which either invaginated or secondarily invaded the third ventricle.

History before diagnosis in childhood craniopharyngioma: associations with initial presentation and long-term prognosis

“…Importantly, growth failure is inversely related to HI and therefore a useful clinical marker to differentiate anatomical/functional levels of damage. The differentiation between anterior (grade I) and anterior and posterior (grade II) HI on preoperative sagittal MRIs (41,42) does not seem to be adequate to discriminate a real infiltration/ invasion of the tuber cinereum from the displacement of the third ventricle floor (43). Simple compression of the hypothalamus by a pure suprasellar CP, probably without functional effects, must be differentiated from invasion of such a structure, almost invariably associated with a progressive weight gain and other neuroendocrine, autonomic, and behavioral alterations.…”

Craniopharyngioma recurrence: the impact of tumor topography

“…According to our systematic review of pathological, surgical, and MRI evidence for an accurate definition of CP-third ventricle relationships, CPs originating in the upper neurohypophysis (median eminence) and adjacent basal hypothalamus (tuber cinereum) correspond to the infundibulo-tuberal, or not strictly intraventricular, category-a group of lesions embedded within the hypothalamus itself. [16][17][18][19] In contrast, CPs originating in the pars tuberalis of the pituitary stalk, below an anatomically intact TVF, quite often push against the third ventricle, mimicking an intraventricular location. Hence, we included these seemingly intraventricular lesions in the suprasellar-pseudointraventricular category.…”

“…Hence, we included these seemingly intraventricular lesions in the suprasellar-pseudointraventricular category. [16][17][18][19] From a surgical perspective, a precise distinction between both topographical categories is paramount.…”

“…9,25,31 Recently, we have verified that the type of anatomical distortion of the mammillary bodies caused by CPs constitutes reliable anatomical information to preoperatively differentiate lesions developing primarily within the TVF from suprasellar tumors, which are merely pushing the third ventricle upward. 19 Precise recognition of the position and relative displacement of the mammillary bodies can be made on conventional T1-weighted MRI, with an acute mammillary body angle (< 60°) characteristic of an infundibulo-tuberal topography, whereas an obtuse angle (> 90°) denotes a primarily suprasellar CP pushing the intact TVF upward (pseudointraventricular type). 9,19 Preoperative MRI identification of the type of optic chiasm distortion caused by the CP also allows precise definition of the tumor topography in many cases.…”

“…Nevertheless, among this latter type, it is the destruction and gliotic transformation of the basal hypothalamus that markedly reduces the likelihood of safe radical removal of the mass. 17,19 Modern high-resolution MRI sequences, such as heavily T2-weighted and fast imaging employing steady-state acquisition (FIESTA), may provide accurate information to define the relation between CPs and surrounding anatomical structures. In particular, these sequences have proven extremely useful in identifying the anatomical integrity and position of the TVF, even when it has been distorted by a large mass.…”