Non-compressive disorders of the chiasm.
Chiasmal dysfunction produces a characteristic clinical picture, regardless of the mechanism. In most cases a compressive lesion is the cause. In occasional cases, however, no such extrinsic mass is found and other possible etiologies must be explored. In some of these cases, the pathologic process is identifiable with appropriate neuroimaging. For example, inflammation, infiltrative tumors, and radiation necrosis produce intrinsic chiasmal enhancement. Chiasmal ischemia may require specialized magnetic resonance (MR) sequences for diagnosis. Chiasmal hemorrhage, trauma and chiasmal herniation typically produce distinctive changes on noncontrasted imaging. In cases of metabolic insult, either toxic or hereditary, radiographic changes are typically absent. In each of these, the correct diagnosis can usually be made with a combination of clinical and radiographic features.
Department of Ophthalmology, Indiana University Medical Center, Indianapolis, IN, USA.
Valerie A
VA
Purvin
Aki
A
Kawasaki
D004677:Encephalocele / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D020300:Intracranial Hemorrhages / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D007511:Ischemia / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D059906:Neuroimaging / Q000379:methods; D029242:Optic Atrophy, Hereditary, Leber / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D009897:Optic Chiasm / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology*; D019574:Optic Nerve Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D011832:Radiation Injuries / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography