Visual evoked potential in the management of pituitary tumor during pregnancy.

We examined a pregnant woman with chiasmal syndrome in the late stage of pregnancy. Her vision was determined to be seriously threatened after 31 weeks' gestation. Study of the latency of preoperative visual evoked potentials (VEPs) in other patients with pituitary tumor showed that insofar as latency is not delayed, surgical decompression is expected to be followed by functional improvement of the optic pathway. We monitored optic nerve function by serially recorded VEPs, and labor was induced at 38 weeks because there had been no delayed response up to that time. After a decompressive operation, visual field and visual acuity recovered normally. Serially recorded VEPs can provide a useful monitor along with visual field and acuity tests in guiding therapy for a patient with threatened vision in late pregnancy and in determining whether or when to induce labor.