Intraoperative bilateral cavernous sinus sampling for ACTH measurements during transsphenoidal pituitary surgery in patients with Cushing's disease.

Intraoperative bilateral cavernous sinus sampling combined with rapid ACTH measurement was performed in a pilot study in seven patients with Cushing's disease during transsphenoidal pituitary surgery before and immediately after removal of the ACTH-producing pituitary microadenoma. Before tumor removal a gradient in ACTH concentrations greater than 1.5:1 toward the side of the tumor was found in six patients whereas ACTH concentrations in the right and left cavernous sinuses were similar in one patient with a midline tumor. Immediately after tumor removal, six of seven patients showed variable decreases in ACTH levels in the ipsilateral and/or contralateral side, whereas in one patient the ACTH levels in cavernous sinuses failed to reflect successful tumor removal. These results indicate that intraoperative bilateral cavernous sinus sampling combined with rapid ACTH measurement may be useful to confirm and lateralize ACTH-producing pituitary microadenomas during surgery, but ACTH levels measured immediately after tumor removal do not always predict surgical cure.