RETROSELLAR ARACHNOIDAL CYST AS UNUSUAL CAUSE OF HOMONYMOUS HEMIANOPIA

Background. Arachnoidal cysts are cystic lesions filled with a cerebro spinal-fluid-like content within the leptomeninges. Usually arachnoida l cysts represent, a congenital malformation. Clinical signs (increase d intracranial pressure and/or neurological defects) may become appare nt in children or young adults. Patient. A sixteen year old boy was re ferred to our outpatient clinic because of blurred vision in both eyes since five days. The patient complained of cephalgia and of an increa sed sleep requirement in the last two weeks. Morphological findings we re within the normal range. The visual acuity was 0.7 in the right eye and 0.2 in the left eye. The visual fields showed an incomplete homon ymous hemianopia to the right. The CT and MRI revealed a retrosellar a rachnoidal cyst. Two weeks after fenestration of the cyst the visual a cuity had risen to 1.3 in both eyes and the visual field defects had d isappeared nearly completely. Conclusion A retrosellar arachnoidal cys t can impair the visual pathway. Early fenestration prevents permanent damage.