The use of intercavernous sinuses phlebography in the diagnosis of ACTH-secreting microadenomas

The use of intercavernous sinus phlebography in the diagnosis of pituitary adenomas has enabled the collection of selective venous samplings of the inferior petrosal sinuses (IPS), where pituitary hormones can be measured before becoming excessively diluted in the systemic circulation. This approach has been particularly useful in patients affected by ACTH-secreting microadenomas, whose diagnosis and preoperative localization can be very difficult. Five female patients, 30–53 years old, suffering from hyperadrenocorticism have been studied. The basal and dynamic hormonal assessment indicated an ACTH-dependent hyperadrenocorticism, although the computed tomography of the sella turcica, performed in all the patients, was negative in 3 patients and doubtful in 2. The perihypophyseal phlebography showed a small left-sided intrasellar expansive process in patient no. 1 and a right-sided intrasellar mass in patients no. 2 and 3. The analysis of ACTH concentrations in the IPS and in the peripheral circulation showed the presence of a concentration gradient between the side of presumed adenoma and the contralateral side (2.7 times;p<0.01) and between the side of the presumed adenoma and the periphery (3.4 times;p<0.01). No significant difference was found between the ACTH concentration in the contralateral IPS and that of the periphery. Surgery confirmed the presumed diagnosis in all cases.