REVIEW PAPER

The inferior petrosal sinus: a comprehensive reviewwith emphasis on clinical implications

Martin M. Mortazavi & Christoph J. Griessenauer &

Sanjay Krishnamurthy & Ketan Verma & Marios Loukas &R. Shane Tubbs

Received: 1 December 2013 /Accepted: 29 January 2014 /Published online: 14 February 2014# Springer-Verlag Berlin Heidelberg 2014

AbstractIntroduction The inferior petrosal sinus is an important com-ponent of the cerebral venous system with implications indiagnosis and treatment of a variety of diseases such asCushing’s disease, carotid cavernous, and dural arteriovenousfistulas.Methods This manuscript will review the anatomy, embryol-ogy, and clinical implications of the inferior petrosal sinus.Conclusions Knowledge of the inferior petrosal sinus is ofgreat importance for open surgical approaches to the skullbase and endovascular access to the cavernous sinus and sellarregion.

Keywords Inferior petrosal sinus . Anatomy . Skull base .

Pathology

Introduction

The inferior petrosal sinus (IPS) is an important paired cere-bral venous channel at the base of the skull that drains thecavernous sinus and receives inflow from auditory structures

and brain stem along its course prior to emptying into thejunction of the sigmoid sinus and superior jugular bulb. In thejugular foramen, the relationship of the IPS and the cranialnerves is of great importance. Embryologically, the IPS de-velops as a new structure connecting the anterior head vein,precursor of the cavernous sinus, and jugular bulb vesiclevein. Endovascular access to the IPS has important diagnosticand therapeutic utility for a variety of conditions involving thecavernous sinus and sellar regions. This manuscript will re-view the anatomy, embryology, and important clinical impli-cations of the IPS.

Anatomy

The IPS (Figs. 1, 2, 3, and 4) are paired venous structures atthe base of the skull that drain venous blood from the cavern-ous sinus to the junction of the sigmoid sinus and the superiorjugular bulb on each side. Along its course, the IPS receivesvenous drainage from the internal auditory vein, medullaoblongata, pons, and inferior cerebellar surface. It originatesfrom the posteroinferior aspect of the cavernous sinus andtraverses the anteromedial portion of the jugular foramenalong with the meningeal branch of the ascending pharyngealartery. The inferior petrosal sulcus, a groove within the poste-rior cranial fossa at the junction of the petrous portion of thetemporal bone and the basilar part of the occipital bone,provides the bony surrounding. Variations of the relationshipof the IPS and the cranial nerves exiting through the jugularforamen have been reported. In the proximal portion in thejugular foramen, the IPS most commonly courses infe-rior to the horizontal portion of the glossopharyngealnerve. Further distal in the foramen, the IPS courses inan inferolateral direction between the descending portionof the glossopharyngeal nerve anteriorly and the vagusand accessory nerves posteriorly [7, 8, 16, 17]. The IPSenters the internal jugular vein in the lower portion of

M. M. Mortazavi : C. J. Griessenauer : S. Krishnamurthy :K. Verma :R. S. TubbsPediatric Neurosurgery, Children’s of Alabama,Birmingham, AL, USA

M. Loukas : R. S. TubbsDepartment of Anatomical Sciences, St. George’s University, St.George’s, Grenada

R. S. TubbsCentre of Anatomy and Human Identification, Dundee University,Dundee, UK

R. S. Tubbs (*)Children’s Hospital of Alabama, Birmingham, AL, USAe-mail: shane.tubbs@childrensal.org

Childs Nerv Syst (2014) 30:831–834DOI 10.1007/s00381-014-2378-7

the jugular foramen or even below the skull base whereit lies lateral to the glossopharyngeal, vagus, and spinalaccessory nerves [11, 19].

Embryology

The medial head vein or vena capitis medialis occurs at theearly stage of the development of the cerebral venous systemand lies medial to the emerging cranial nerve roots and oticvesicle. At the 5–10-mm stage, the medial head vein hasdisappeared and is replaced by the lateral head vein or venacapitis lateralis located lateral to the otic vesicle, medial to thetrigeminal nerve, and lateral to the facial and vestibular nerves.It has connected to the precardinal vein, the precursor of the

internal jugular vein. Stems for the anterior, medial, andposterior venous plexuses form off the lateral head vein.Around the 14–18-mm stage, a venous channel parallel tothe lateral head vein connecting these plexuses develops.This channel provides the basis for the cerebral venous struc-tures cranial to the jugular bulb. At the 24–40-mm stage, theposterior component of the lateral head vein has disappeared,while the anterior component remains as the cavernous sinus.At this stage, a new channel, the IPS, medial to the oticvesicle, develops connecting the cavernous sinus to the jugu-lar bulb vesicle vein. At this stage of development, the junc-tion of the IPS with the internal jugular vein is strictly extra-cranial, while in adults, the junction occurs at the anteriorsurface of the jugular bulb (Fig. 5) [12, 15, 20, 21].

Fig. 1 Schematic drawing of the venous sinuses of the skull base

Fig. 2 Cadaveric dissection of the right-sided superior (SP) and inferiorpetrosal (IP) sinuses of the skull base. The trigeminal nerve (T) is locatednear the origin of the two venous pathways from the cavernous sinus

Fig. 3 The inferior petrosal sinus as it enters the jugular foramen and itsrelationship to the glossopharyngeal nerve

Fig. 4 Cadaveric dissection illustrating the basilar venous sinus (upperarrow), the inferior petrosal sinus (middle arrow), and the marginal sinus(lower arrow)

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Clinical implications

Endovascular access to the IPS has important diagnostic andtherapeutic utility for a variety of conditions and requiresprecise understanding of the four drainage patterns related tothe IPS [1, 18]. Most commonly (type 1) and in 45 % ofpatients, the IPS drains directly into the internal jugular vein atthe superior bulb (Fig. 4) with little or no communicationwith the anterior condylar vein (ACV) [6, 11]. In type II,the IPS anastomoses with the ACV before draining intothe internal jugular vein and the ACV then drains intothe vertebral venous plexus. This occurs in 24 % ofpatients [18]. In type III, the IPS drains into the internaljugular vein as a plexus of veins rather than as a singlevein and also occurs in 24 % of patients. This plexusalso drains into the vertebral venous plexus [18]. In theleast common drainage pattern, type IV, occurring in 7 % ofpatients, the IPS predominantly drains into the vertebral ve-nous plexus via the ACV [11].

Fig. 5 Schematic drawing of the embryonic development of thecerebral venous system (precardinal vein (PCC), primitive sig-moid sinus (PSS), primitive transverse sinus (PTS), stem of themiddle cerebral plexus (SMCP), stem of the anterior cerebralplexus (SAP))

Fig. 6 Fifty-nine-year-old femalepresented with increasinglethargy and elevated cortisol forwork-up. A MRI of the brainshowed a small hypodensity inthe posterior inferior part of thepituitary gland (panel a). Inferiorpetrosal sinus sampling waspreformed and consistent withcentral Cushing’s disease. Anangled guide catheter was placedin the left internal jugular vein(panel b). Microcatheters werenavigated into the left andsubsequently the right inferiorpetrosal sinus (panels c and d). Aseries of specimens werecollected from bothmicrocatheters and from the leftfemoral vein sheath before andafter administration ofintravenous corticotropin-releasing hormone. The patientwent on to endoscopic transnasal,transsphenoidal resection of thepituitary adenoma

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The IPS provides endovascular access to test for Cushing’sdisease and treat carotid cavernous and dural arteriovenousfistulas via transvenous embolization. Bilateral inferior petro-sal sampling (BIPSS) is the current gold standard method fordiagnosing Cushing’s disease (Fig. 6) [2, 4, 5, 10, 13, 14]. Inthe early 1990s, Oldfield et al. reported this method consistingof insertion of catheters into the IPS via the femoral veins andinternal jugular veins under angiographic visualization andcollection of blood samples from each sinus. The plasmaadrenocorticotropic hormone (ACTH) levels in these samplesare compared with the levels in the blood obtained peripher-ally. Since the release of ACTH is periodic and the samplingcan take place at an inopportune moment, corticotropin-releasing hormone (CRH) is used to increase the sensitivityof the test. A central to peripheral ratio of ACTH above 3.0 isan indicator of Cushing’s disease. Caveats of the procedureinclude false negative results in the presence of a unilateralhypoplastic or plexiform inferior petrosal sinus [3]. In addi-tion, errors in lateralization of the adenoma can occur due tothe asymmetric drainage of the IPS [3, 15]. Venous angiogra-phy facilitates understanding in variations the venous drainageand helps to avoid such problems [3, 9, 13, 15]. In experiencedhands, BIPSS has a very low risk of complications such aspulmonary embolisms, venous thrombosis, cranial nerve pal-sy, and brain stem vascular damage [7].

Conclusions

Knowledge of the inferior petrosal sinus is of great importancefor open surgical approaches to the skull base andendovascular access to the sellar region and cavernous sinus.

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