Chiasma syndrome in acromegalic patients--correlation of neuroradiologic and neuroophthalmologic findings.

The study evaluated neuroophthalmologic and computerized tomography (CT) findings in 100 patients with somatotrophic adenoma and clinical picture of acromegaly, who underwent transsphenoidal adenomectomy. Prior to the surgery, visual field was normal in 77 patients. The diameter of adenoma in these patients ranged from 8 to 30 mm on CT, and the average value was 13.5 mm. Various kinds of visual field disturbances were present in 23 patients. The diameter of their adenomas ranged between 18 to 35 mm, with the average of 24.7 mm. Compared to visual field defects, CT findings of suprasellar adenoma extension were better correlated with chiasma syndrome (p < 0.001). All patients with suprasellar mass greater than 10 mm had chiasma syndrome. Degenerative adenoma changes (hemorrhagic necrosis), which precipitate abrupt increase in size of the tumor, were more frequently seen in patients with chiasma syndrome. The incidence of chiasma syndrome directly correlates with the degree of suprasellar extension of the tumor.