Cushing's disease; inferior petrosal sinus venography and samplings

Hypersecretion of ACTH in patients with Cushing's syndrome originates from either a pituitary tumor (Cushing's disease) or an ectopic ACTH-secreting tumor. These 2 entities may be clinically indistinguishable, and additional difficulty arise because pituitary microadenomas may be radiologically occult. Recently, bilateral selective venous sampling from the inferior petrosal sinuses became the procedure of choice for confirming a false negative study of a combined hormonal test and pituitary ACTH hypersecretion. We performed selective venous catheterization and sampling for ACTH. The central location of the lesion was detected in 1 case (intersinus gradient = 1.1 : 1), and the remaining 5 cases revealed lateralization of the lesions (intersinus gradient = 3.7 - 20.1 : 1), which correlated well with transsphenoidal microadenomectomies in all the cases. We concluded that selective venous ACTH sampling from the inferior petroal sinus is a reliable and useful aid in the diagnosis of Cushing's disease when standard clinical and biochemical studies are inconclusive