Background. Recurrent pituitary adenomas and localisation of microadenomas potentially cause difficulties during transsphenoidal pituitary surgery. Neuronavigation might improve tumour removal in such cases.

Methods. Between 12/98 and 04/01 transnasal transsphenoidal adenomectomies were performed in 152 patients at our department. In 16 of these patients neuronavigation was chosen as a means of safely approaching the tumour and improving the efficacy of tumour localisation and removal. Mean age of the 7 female and 9 male patients was 51.8±13.7 years. Patients were subdivided according to the underlying pathology, i. e. microadenomas (n=8, mean diameter: 5.75±2.1 mm), and recurrent adenomas (n=8). The imaging of adenomas was achieved in preoperatively obtained 1 mm transversely reconstructed magnetic resonance sections from a dynamic enhanced 3D-FFE sequence (Gyroscan 1.5 Tesla, Philips). Contour-guided surgery via a transnasal transsphenoidal approach to the sella region was performed using the MKM navigation microscope (Zeiss).

Results. Endocrinologic studies revealed secretion of growth hormone (GH), ACTH, and follicle stimulating hormone (FSH) in 5, 4, and 1 patient, respectively. The remaining 7 adenomas did not secrete any hormones. All pituitary tumours were accurately localised by neuronavigation. In all recurrent macroadenomas, the tumours were rapidly and safely approached through the scarred tissue and the tumour volume was significantly reduced. Neither intraoperative nor postoperative complications occurred in these patients. In hormone-secreting pituitary tumours with far lateral localisation, endocrinologic abnormalities were corrected in 5 patients, while hormone secretion was significantly decreased in 3 patients. In 1 patient with histologically verified adenoma, hormone secretion did not significantly change following surgical removal.

Conclusions. Neuronavigation in pituitary surgery is of use in only a small number of cases. Nevertheless, we suggest that contour-guided, transsphenoidal adenomectomy may prove helpful in approaching recurrent adenomas and localising lateral microadenomas.