The hypophysis

Fluoroscopic frameless stereotaxy for transsphenoidal surgery

OBJECTIVE

To assess the value of frameless fluoroscopy-guided stereotactic transsphenoidal surgery using the FluoroNav Virtual Fluoroscopy System (Medtronic Sofamor Danek, Inc., Memphis, TN).

METHODS

Twenty consecutive patients undergoing transsphenoidal surgery for sellar lesions were assigned to transsphenoidal surgery with or without computer-assisted fluoroscopic image guidance using the FluoroNav system. Prospective data regarding patient age, sex, lesion characteristics, operative time, and treatment cost were obtained.

RESULTS

Although patients in the FluoroNav group were, on average, 17 years younger than the patients in the control group, more patients with recurrent adenomas were treated in the image guidance group. No other significant differences between the groups were found. FluoroNav provided accurate, continuous information regarding the anatomic midline trajectory to the sella turcica as well as anatomic structures (e.g., sella, sphenoid sinus) in the lateral view. No patient required reversion to intraoperative videofluoroscopy. No statistically significant differences were found with regard to preincision setup time, operative time, or cost. FluoroNav allowed procedures to be performed with significantly fewer x-rays being taken.

CONCLUSION

Fluoroscopic computer-assisted frameless stereotaxy furnishes accurate real-time information with regard to midline structures and operative trajectory. Although it is useful in first-time transseptal transsphenoidal surgery, its primary benefit is realized in recurrent surgery.

Pituitary surgery for endocrine disorders

The use of pituitary surgery for patients with over-production of growth hormone, corticotrophin and prolactin is reviewed. The value of specialized neuroradiological techniques is discussed including computerized tomography, air-encephalography and cavernous sinus venography. The indications for transcranial as opposed to trans-sphenoidal surgery are considered. The place of trans-sphenoid surgery in the treatment of acromegaly is emphasized and the indications for surgical treatment are reviewed. The two syndromes due to over-production of ACTH are considered--Cushing's disease and Nelson's syndrome. The increasing use of pituitary surgery for the treatment of Cushing's syndrome due to increased ACTH production is noted, but a warning is given about the small ACTH-secreting pulmonary carcinoid tumour that may closely mimic Cushing's disease. The difficulties encountered in trying to treat patients with Nelson's syndrome are stressed. It is recommended that in the rate case where total adrenalectomy is required in Cushing's disease, pituitary irradiation should be given before or shortly after adrenalectomy. The present position relating to the surgical treatment of the small prolactin-secreting pituitary tumour is reviewed. Published data and personal experience suggests that for many of these patients, treatment with bromocriptine is preferable to trans-sphenoidal surgery. Large prolactinomas usually need transfrontal surgery and X-ray therapy, sometimes followed by bromocriptine treatment. The need for steroid cover for pituitary surgery is discussed and it is suggested that a glucocorticoid with less salt-retaining action than cortisol should be used. The importance of post-operative endocrine assessment is emphasized and a convenient method suggested. The incidence of complications after transsphenoidal surgery is low, although panhypopituitarism occurred in 14% of the cases reported.

Water intoxication after hypophysectomy

A case of excessive water retention after hypophysectomy is recorded. Its probable cause, inappropriate secretion of ADH, is explained and the diagnosis and management discussed. Three other recorded cases occurring after hypophyseal surgery are mentioned. The importance of postoperative electrolyte measurements in early diagnosis and management is emphasized.