An algorithm to improve lateralization accuracy of inferior petrosal sinus sampling: procedural nuances for complex patterns of venous drainage. Patient series

Abstract

Background: Inferior petrosal sinus sampling (IPSS) is a useful technique in the diagnosis of Cushing's disease (CD) when the imaging finding is negative or equivocal. Different authors have reported considerable variability in the ability to determine tumor laterality with IPSS. Here the authors present a retrospective case series of 7 patients who underwent IPSS using a systematic algorithm to improve lateralization accuracy by identifying optimal sampling sites on the basis of individual cavernous sinus drainage patterns in each patient.

Observations: Of the 7 patients identified, 6 were determined to have CD and subsequently underwent surgery. IPSS was accurate in all patients from whom laterality was predicted. Arterial and venous angiography were used to define cavernous sinus drainage patterns and determine optimal sampling sites. All patients who underwent surgery achieved hormonal cure.

Lessons: All IPSS predictions of lateralization were correct when available, and all patients who underwent surgery achieved hormonal cure. Advances in angiographic techniques for identification of the site of primary drainage from the cavernous sinus and subsequent optimization of microcatheter placement may improve the ability to predict tumor laterality.

Keywords: ACTH = adrenocorticotropic hormone; CD = Cushing’s disease; CRH = corticotropin-releasing hormone; Cushing’s disease; IPS = inferior petrosal sinus; IPSS; IPSS = inferior petrosal sinus sampling; MRI = magnetic resonance imaging; endovascular; inferior petrosal sinus sampling; pituitary.

FIG. 1.

Algorithm for the diagnosis of Cushing’s disease from an ACTH-dependent Cushing’s syndrome. IPSS is used when pituitary MRI is unable to identify a likely ACTH-secreting adenoma.

FIG. 2.

IPSS procedural algorithm used in each of the patients. We attribute this systematic approach to the improved accuracy of lateralization in our series. In the event of an IPS that cannot be cannulated or visualized, we perform retrograde venography to determine the site of primary drainage from the cavernous sinus. If this fails to identify an optimal sampling location, we perform contralateral venography and finally arterial angiography with delayed roadmapping.

FIG. 3.

A: Lateral projection of the venous phase of a right internal carotid artery digital subtraction angiogram showing anterior drainage of the right cavernous sinus through the pterygoid plexus (red arrow). B: Posteroanterior (PA) view of a venogram from the right cavernous sinus performed after identifying and cannulating the right IPS. An atretic left IPS can be visualized (red arrow). C: PA view of final catheter sampling positions in the right cavernous sinus and left IPS–internal jugular vein junction (red arrows).

FIG. 4.

A: MRI of patient 6. Axial T2 MRI without contrast showing a small hyperintensity in a left-central location, just inferior to the infundibulum (red arrow). This hyperintensity was determined not to be a tumor intraoperatively, prompting exploration and identification of the microadenoma in the right pituitary gland. B: Lateral projection of a venogram of the right cavernous sinus showing drainage through a complex venous plexus rather than a single IPS (red arrow). C: Posteroanterior view of final catheter sampling positions showing placement in the right cavernous sinus and left IPS (red arrows).