Bilateral simultaneous sampling of the cavernous and inferior petrosal sinuses in the differential diagnosis of Cushing’s disease

Background. Currently, the “gold standard” of differential diagnosis of Cushing’s disease is inferior petrosal sinus sampling and measurement of the adenocorticotropic hormone (ACTH) level. The studied literature data indicate a wide variability in the sensitivity and specificity of inferior petrosal sinus sampling in the range of 85–100 and 67–100 %, respectively, which can lead to an erroneous diagnosis of the source of ACTH hyperproduction and, as a consequence, to incorrect and untimely treatment.Aim.To improve the results of differential diagnosis of Cushing»s disease by using bilateral simultaneous sampling of the cavernous and inferior petrosal sinuses.Materials and methods. Cohort single-center retro/prospective study of 70 patients with confirmed ACTH-dependent Cushing’s syndrome. For the purpose of differential diagnosis, a number of indicators were calculated: central-peripheral ratio, prolactin-normalized ACTH ratio, successful catheterization. Sampling results were evaluated in comparison with contrast-enhanced pituitary magnetic resonance imaging data and intraoperative data.Results. The study of the central-peripheral ratio showed the need to assess it simultaneously at the level of the cavernous and inferior petrosal sinuses. This approach makes it possible to significantly increase the sensitivity and specificity of the applied gradient to 93.1 and 85.7 %, respectively. Prolactin-normalized ACTH ratio is a second line predictor in the differential diagnosis of Cushing’s disease with sensitivity and specificity reaching 94.7 and 28.6 %, respectively. The gradient of successful catheterization is a reflection of possible hemodynamic features of a particular sinus, does not serve as an indicator of the correct positioning of microcatheters in the vascular bed.Conclusion. Bilateral simultaneous sampling of the cavernous and inferior petrosal sinuses is an effective method of differential diagnosis of Cushing’s disease and ectopic ACTH-dependent syndrome.