An assessment of petrosal sinus sampling for localization of pituitary microadenomas in children with Cushing disease

Context: Pituitary adenomas in Cushing disease ( CD) are usually small and difficult to visualize. Bilateral inferior petrosal venous sampling (BIPSS) before and after ovine CRH stimulation is reserved for patients who have ACTH-dependent Cushing syndrome and negative magnetic resonance imaging (MRI) or positive MRI but inconsistent biochemical data. Objective: The objective of the study was to evaluate the usefulness of BIPSS as a tool for localization of a pituitary adenoma in children with CD. Design: The study was a retrospective review of the records of 141 children who were admitted for evaluation of CD from 1982 to 2004. Setting: The study was conducted at a tertiary care center. Interventions and Outcome Measures: Lateralization of ACTH secretion during BIPSS was compared with MRI and surgical findings for the localization of a microadenoma. Results: A total of 94 patients, 49 males and 45 females with an age range of 5.3 to 18.7 yr ( 13 +/- 3.2 yr), underwent BIPSS. Localization of a microadenoma by BIPSS agreed with surgical location in only 58% of the cases (95% confidence interval, 43 - 66). The combined use of information from the MRI and inferior petrosal venous sampling did not predict the location of the tumor more frequently than MRI alone ( P > 0.1), which in this study localized a lesion in 39% of the patients ( 95% confidence interval, 28 - 50). The procedure was completed successfully in all patients, and no serious complications were recorded. Conclusions: Although BIPSS was safe and well tolerated in an experienced center, lateralization of the ACTH gradient during BIPSS was a poor predictor of the site of the adenoma in children with CD.