[A case of pituitary adenoma presenting binasal inferior quadrants hemianopsia]

Visual field defect due to pituitary adenoma ordinarily shows bitemporal hemianopsia. But we experienced a case presenting binasal inferior quadrants hemianopsia. A 60-year-old woman was admitted to our hospital complaining of headache and blurred vision. At ophthalmologic examination, the visual acuity on the right was 0.02 and on the left 0.3. Visual field showed a loss of bilateral inferior nasal quadrants. There was neither pallor nor edema of either of the optic disks. A computerized tomography (CT) scan showed an enhancing mass in the intra- and suprasellar region. But despite remarkable suprasellar expansion of the tumor, the straight view of bilateral carotid angiograms revealed no elevation of the first part of the anterior cerebral arteries (ACA). On the lateral view, the terminal portion of the precommunicating part of the left ACA showed rather marked anteroinferior displacement. 2 mm thin sliced CT scans at the suprasellar region revealed that the left internal carotid artery had been touching the lateral portion of the tumor and the ACA had been displaced anteriorly by the tumor. Two weeks after admission, transsphenoidal tumor resection was carried out. Total removal was achieved and histological examination showed that the tumor was nonfunctioning chromophobe adenoma. The postoperative course was uneventful except for transient diabetes insipidus. The patient's visual acuity rapidly improved to 0.8 on the right and 0.5 on the left two weeks after operation. Although there was still a tendency for left inferior nasal field defect, remarkable improvement was obtained subjectively and objectively. According to the findings of CT scans and cerebral angiograms, binasal hemianopsia may have been produced by the mechanism as follows.(ABSTRACT TRUNCATED AT 250 WORDS)