title: [Chiasmatic syndromes-diagnostic possibilities with computerized tomography (CT)].
abstract: The normal suprasellar subarachnoid space (so-called "suprasellar hexagon") and its content are fairly well demonstrated by CT. Abnormal appearance (obstruction, stenosis, asymmetry) of this space is always suspect of a suprasellar space occupying lesion. Enhancing (intravenous application of iodine containing contrast medium) helps to delineate the exact tumor extension. The point of origin--important for deciding on the nature of a lesion--is often difficult to determine. The CT-pattern itself is not specific for a certain kind of tumor. We have observed a typical chiasmatic syndrome with all meningiomas of the tuberculum sellae, with 75% of the chromophobe adenomas and with 50% of the craniopharyngiomas. Absence of this syndrome was due to high position of the tumor (craniopharyngiomas) or to parasellar extension of the lesion (chromophobe adenomas). Diagnosis of recurrent tumor is difficult; it must be based on the post-operative CT-examination. Chiasmatic syndromes not due to the pressure effect of a space occupying lesion (i.e. chiasmatic syndromes of vascular, toxic or degenerative origin) can not be assessed directly by CT.
mesh_terms: D000239:Adenoma, Acidophil / Q000000981:diagnostic imaging; D000238:Adenoma, Chromophobe / Q000000981:diagnostic imaging; D003397:Craniopharyngioma / Q000000981:diagnostic imaging; D005128:Eye Diseases / Q000000981:diagnostic imaging; D006801:Humans; D008579:Meningioma / Q000000981:diagnostic imaging; D009897:Optic Chiasm; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging; D013100:Sphenoid Bone / Q000000981:diagnostic imaging; D013577:Syndrome; D014057:Tomography, X-Ray Computed; D014786:Vision Disorders / Q000000981:diagnostic imaging
vernacular_title: Chiasmasyndrome-computertomographische Diagnostik