Posterior Fossa Venous Drainage

This paper aims to make simple the evaluation of the main veins related to the brainstem and cerebellum. Posterior fossa venous drainage is best understood in context with its three main collectors: superior: toward the Vein of Galen; posterior: toward the torcular complex; and anterior: toward the superior petrosal sinus. A fourth possible drainage path, often harder to distinguish, is directed toward the inferior petrosal sinus. Veins of these four systems are frequently connected to one another. Despite traditionally being considered less regular than its arterial disposition, posterior fossa venous anatomy follows specific patterns that are easy to identify. The three more representative veins of each venous confluent have been selected, to help in recognizing them angiographically. Since pial large veins are primarily located over the surface of the encephalon, most related anatomical structures can be confidently identified. This is of special interest when angiographic 2D or 3D studies are evaluated and provide fundamental assistance in locating precise structures. To better aid in understanding venous disposition, an overview of embryologic and fetal development is also discussed.

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

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.

The Angle of the Microguidwire on the Lateral Projection: a Prediction of Cannulation of the Occluded Inferior Petrosal Sinuses for the Transvenous Embolization of Cavernous Sinus Dural Arteriovenous Fistulas

OBJECTIVE: To describe that the angle of the guidwire on lateral projection under fluoroscopic image is a prediction of cannulation of the occluded inferior petrosal sinus in the transvenous embolization of cavernous sinus dural fistulas.METHODS: From January 2018 through January 2021, 12 consecutive cavernous sinus dural fistulas with ipsilateral inferior petrosal sinus occlusion identified in 12 patients were cured by cannulation of the occluded ipsilateral inferior petrosal sinus. Clinical, radiologic and procedure data of the 12 patients were retrospectively reviewed. The angle of microguidewire between on lateral projection under fluoroscopic image between the inferior petrosal sinus and the internal jugular vein was measured by 180°Protractor(Deli Group Co., LTD, Zhejiang, China). RESULTS: In the 12 patients, access via the occluded ipsilateral inferior petrosal sinus was primarily attempted as the transvenous approach. During the procedure, the angle of microguidwire on lateral projection under fluoroscopic image between the inferior petrosal sinus and the internal jugular vein was 117°±7°, which is very useful to confirm the cannulation of the occluded inferior petrosal sinus. Complete occlusion was achieved in all fistulas, with no procedure-related morbidity or mortality. Postprocedural symptom was improved in all patients. CONCLUSION: Cannulation of an occluded inferior petrosal sinus is possible and reasonable as an initial access attempt for cavernous sinus dural fistulas. The angle of microguidwire on the lateral projection under fluoroscopic image can help to confirm the orifice of the occluded inferior petrosal sinus.