Do Inferior Petrosal Sinus Drainage Variations Affect the Sampling Lateralization Results?

Objective: To evaluate the relationship between adenoma lateralization and the variations in petrosal sinus drainage. Materials and Methods: A total of 24 patients diagnosed as ACTH dependent Cushing Syndrome (CS) in the Department of Endocrinology and Metabolism Disorders between May 2006 and May 2012 were evaluated. The patient files for data, including laboratory results and imaging records, were analyzed retrospectively. MRI was performed using a 1.5-T scanner. The femoral vein was cannulated using the Seldinger technique and bilateral venous sheaths were inserted for bileteral inferior petrosal sinus sampling (BIPSS). Results: Microadenomas were detected with MRI in 12 patients. Right lateralization has been determined in 12 patients (54.5%), left lateralization in 5 patients (22.7%) and central gradient in 2 patients (22.8%). No peripheral/ central gradient was obtained by BIPSS in 3 patients compatible with an ectopic source of ACTH. Pituitary surgery was performed in 19 patients. Conclusion: BIPSS may avoid unnecessary pituitary surgery. Asymmetric drainage may affect the results of lateralization. This study suggest that drainage variations may have subgroups.