Infundibulo-tuberal CPs represent a major topographical category of lesions with a primary subpial development at the floor of the third ventricle. These lesions expand within the hypothalamus itself and subsequently occupy the third ventricle; consequently, they can be classified as not strictly intraventricular CPs. A tight attachment to the hypothalamus and remnants of the third ventricle floor is the pathological landmark of infundibulo-tuberal CPs.
Two different topographies might be considered among IVC: strict and non-strict intraventricular location. Non-strictly IVC have wider and tighter adhesions to third ventricle boundaries and this subtype is associated with a worse outcome.
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.
Background and Purpose-Even though the utilization of substrates alternative to glucose may play an important role in the survival of brain cells under ischemic conditions, evidence on changes in substrate selection by the adult brain in vivo during ischemic episodes remains very limited. This study investigates the utilization of glutamate, glutamine, and GABA as fuel by the neuronal and glial tricarboxylic acid cycles of both cerebral hemispheres after partially reversible focal cerebral ischemia (FCI). Methods-Right hemisphere infarct was induced in adult Long-Evans rats by permanent occlusion of the right middle cerebral artery and transitory occlusion of both common carotid arteries.(1,2-13 C 2 ) acetate was infused for 60 minutes in the right carotid artery immediately after carotid recirculation had been re-established (1-hour group) or 23 hours later (24-hour group). Extracts from both cerebral hemispheres were prepared and analyzed separately by 13 C nuclear magnetic resonance and computer-assisted metabolic modeling. Results-FCI decreased the oxidative metabolism of glucose in the brain in a time-dependent manner. Reduced glucose oxidation was compensated for by increased oxidations of ( 13 C) glutamate and ( 13 C) GABA in the astrocytes of the ipsilateral hemispheres of both groups. Increased oxidative metabolism of ( 13 C) glutamine in the neurons was favored by increased activity of the neuronal pyruvate recycling system in the 24 -hour group. Conclusions-Data were obtained consistent with time-dependent changes in the utilization of glutamate and GABA or glutamine as metabolic substrates for the glial or neuronal compartments of rat brain after FCI. (Stroke.
Experimental models of traumatic brain injury (TBI) provide a useful tool for understanding the cerebral metabolic changes induced by this pathological condition. Here, we report on the time course of changes in cerebral metabolites after TBI and its correlation with early brain morphological changes using a combination of high-resolution proton magnetic resonance spectroscopy ((1)H MRS) and magnetic resonance imaging (MRI). Adult male Sprague-Dawley rats were subjected to closed head impact and examined by MRI at 1, 9, 24, 48, and and 72 h after the injury. Extracts from funnel frozen rat brains were then obtained and analyzed quantitatively by high-resolution (1)H MRS. Finally, statistical multivariate analysis was carried out to identify the combination of cerebral metabolites that best described the time evolution of diffuse TBI. The temporal changes observed in the concentration of cerebral metabolites followed three different patterns. The first pattern included taurine, threonine, and glycine, with concentrations peaking 24 h after the injury. The second pattern included glutamate, GABA, and alanine, with concentrations remaining elevated between 24 and 48 h post-injury. The third one involved creatine-phosphocreatine, N-acetylaspartate, and myo-inositol, with concentrations peaking 48 h after the injury. A multivariate stepwise discriminant analysis revealed that the combination of the organic osmolytes taurine and myo-inositol allowed optimal discrimination among the different time groups. Our findings suggest that the profile of some specific brain molecules that play a role as organic osmolytes can be used to follow-up the progression of the early diffuse brain edema response induced by TBI.
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