VALUE OF VISUAL-EVOKED POTENTIAL MONITORING DURING TRANS-SPHENOIDAL PITUITARY SURGERY

The visual outcome of 22 patients undergoing trans-sphenoidal excision of pituitary macroadenomas with intraoperative flash visual evoked po tential (VEP) monitoring (Group A), was compared with a non-randomized group of 14 patients who had undergone similar operations without VEP monitoring (Group B). Tumour size, preoperative visual acuity, periph eral fields, and latencies and amplitudes of P1 and P2 were analysed t o ascertain the best predictor of postoperative visual function. It wa s found that patients in Group A had a significantly greater improveme nt in field defects than those in Group B. There was no difference in postoperative improvement in visual acuity between the two groups. Non e of the variables analysed were good predictors of visual outcome.