ROLE OF HORMONAL EXPLORATION IN AVOIDING THE FAILURES OF SURGERY FOR CUSHINGS-DISEASE

Patients with Cushing's disease are not cured by transsphenoidal micro surgery in about 30% of the cases. Beside the problem of invasive macr oadenomas, these failures are due either to diagnostic errors, or to v ery small microadenomas that could no be found. Positive diagnosis of hypercortisolism is quite straightforward and the problem is sensitivi ty rather than specificity. Primary adrenocortical hypercortisolism sh ould not be mistaken. Depression-related hypercortisolism can be diffi cult to distinguish from Gushing disease: most cases are recognized af ter clinical story and CRF stimulation test. Ectopic ACTH secretion by a carcinoid tumor represents at least 8% of ACTH-dependant hypercorti solism. It cannot be reliably distinguished from corticotroph microade noma by either classical dynamic tests or anterior pituitary imaging. However measurements of ACTH in the inferior petrosal sinus under basa l condition and CRF stimulation allow the diagnosis of central or peri pheral ACTH secretion with a quasi 100% sensitivity and specificity. I n contrast this technique is of poor help for the diagnosis of lateral ization of corticotroph microadenomas, for which it gives erroneous re sults in 25 to 50% of the cases. Rapid intraoperative measurement of A CTH in peripituitary blood seems a more reliable approach. In our seri es it gave correct results in ii out of 12 cases. In 1995 hormonal exp loration of Gushing disease should limit the failures of anterior pitu tary surgery to the cases of invasive macroadenomas that cannot be com pletely removed.