gms | German Medical Science

Background: Diagnostics and treatment of ACTH-dependent hypercortisolism are challenging. We are confronted with two major problems: The distinction between ACTH overproduction due to pituitary lesion from ectopic ACTH production is not always obvious in conventional biochemical tests. Localization of pituitary lesions is the second problem as microadenomas are often missed in MRIs. To define the diagnosis we performed bilateral ACTH sampling in BIPSS and evaluated its value for tumor lateralization. Can BIPSS improve the outcome when MRI is negative?

Materials and methods: Prior to BIPSS standard biochemical tests were performed. All the patients received sella MRI..During catheterization timing of the ACTH sampling before and after CRH stimulation was - 5, 0, 5, 10, 15 min. Prolactin was measured as index of pituitary venous drainage. Diagnostic criteria included the central vs peripheral ACTH ratio (IPS:P) and right vs left ratio.

Results: 13 of 23 patients with ACTH-dependent hypercortisolism showed no clear sella MRI findings. These patients underwent BIPSS. 11/13 patients obtained an IPS:P ratio 3-83 suggesting Cushing’s disease. 1/13 patient was detected to have an ectopic ACTH secretion. 1/13 patient Nelson's syndrome. 10/13 patients underwent transsphenoidal surgery. 9/10 patients showed right to left ACTH gradient of 3-78.1One patient showed no side gradient. 5/10 patients showed remission after surgery and 5 patients required an early second look operation taking tumor lateralization predicted in BIPSS into consideration. In only 2 cases, tumor lateralization in BIPSS was incorrect. A microadenoma was found on the other side. 3/5 patients showed remission after revision operation. In total 8/10 patients showed remission after transsphenoidal surgeries. The accuracy for remission was in total 80%.

Conclusion: BIPSS is an old tool in the diagnostic of Cushing Syndrome, invasive and technically demanding. In our patient population it turned out to be a method with high success ratio with no major complications. It’s a powerful tool to distinguish central ACTH overproduction from etopic ACTH secretion and should be reserved for selected patients. Furthermore we believe that BIPSS can be applied for the preoperative localization of pituitary microadenomas when MRI studies are not clear.