statdx/docs_md/articles/cavernous-sinus_2a0f0fa0-b60c-4a90-82de-9d78bdf42463.md

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title	docid	authors	breadcrumbs	category	cmeTopicId	documentVersionId	imageCount	lastUpdated	pageDescription	pageKeywords	pageTitle	enhancedTitle	type	breadcrumbs
Cavernous Sinus	2a0f0fa0-b60c-4a90-82de-9d78bdf42463	key value 1fa14dfd-71ea-4960-908e-e720313bc63a Santhosh Gaddikeri, MD key value 94f835c8-fa13-4e8a-995b-53048e6b0605 Philip R. Chapman, MD	name slug treeNodeId Head and Neck head-and-neck 5c1f8e17-7acd-48d8-9d55-f9f8c2cad850 name slug treeNodeId Anatomy anatomy 5deb3a75-762a-49d7-8d1c-dffda4a1b190 name slug treeNodeId Orbit orbit 46f22f52-3729-40de-ab3e-766ff16954b6 name slug treeNodeId Cavernous Sinus cavernous-sinus null	Head and Neck	2d946367-4532-4e99-b9e2-3b3761890929	8ef524b6-81f6-4647-a8c2-a8a8a7b6a669	28	02/19/24	Cavernous Sinus	Head and Neck, Anatomy, Orbit, Cavernous Sinus	Cavernous Sinus | STATdx	Cavernous Sinus	ANATOMY	Head and Neck Anatomy Orbit Cavernous Sinus

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title: "Cavernous Sinus" docid: "2a0f0fa0-b60c-4a90-82de-9d78bdf42463" authors:

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TERMINOLOGY

• Abbreviations

  • Cavernous sinus (CS)

• Definitions

  • Paired venous lakes with multiple septa within located lateral to sella turcica, pituitary & sphenoid sinus, & medial to mesial temporal lobe
  • CSs drain multiple veins from orbit, sylvian fissure, middle & anterior fossa; ultimately provide venous drainage posteriorly & inferiorly via inferior petrosal, superior petrosal, & basilar venous sinuses
  • Described as anatomic jewel box due to its complex contents, including several cranial nerves & internal carotid artery (ICA)
  • Term cavernous sinus 1st used by Winslow in 1734

IMAGING ANATOMY

• Overview

  • Valveless, septated dural venous sinuses of central skull base, present on either side of sella
  • Extradural in location communicating with extradural space of spine & orbits, in contrast to other venous sinuses, which are located between 2 layers of dura
  • Important given location, relationship to sella, pituitary gland, & internal contents, including multiple cranial nerves & cavernous ICA

• Anatomy Relationships

  • Boundaries - Boat-shaped structure, narrowest anteriorly & widest posteriorly, bounded by dura with 5 walls, including anterior, posterior, medial, lateral, & superior/roof - Superior: Extends from base of anterior clinoid process to posterior clinoid process - Lateral: Bordered by 2 layers of dura - Medial: Bordered by lateral margin of sella & lateral wall of sphenoid sinus with carotid sulcus - Anterior: Extends to anterior clinoid process & superior orbital fissure (SOF) below it - Posterior: Extends to posterior clinoid process, lateral margin of upper clivus, & petroclival junction, extending laterally to point just medial to trigeminal impression
  • Superior wall/roof - Extends from optic strut & SOF anteriorly to petrous apex (PA) & tentorial incisura posteriorly - Medial margin of roof contiguous with diaphragma sellae - Oculomotor triangle, triangular-shaped portion of CS roof created by 3 dural folds - Lateral margin of roof separated from lateral wall of CS by cord-like thickening of dura called anterior petroclinoid foldthat extends from tentorial edge at PA to anterior clinoid process - Separate fold extends from tentorial edge at PA to posterior clinoid process, posterior petroclinoid fold - Thin band of dura, interclinoid fold, extends from anterior clinoid process to posterior clinoid process - CNIII, along with its sleeve of arachnoid (oculomotor cistern), pierces roof at oculomotor triangle - CNIV enters posterolateral aspect of oculomotor triangle just posterior to CNIII - Small portion of roof passes inferomedial to anterior clinoid process where dural roof merges with dura, forming proximal & distal dural rings
  • Lateral wall - Sail-shaped dural sheet that extends from SOF & anterior clinoid process anteriorly to PA posteriorly; faces medial temporal lobe - Consists of thick dural membrane that typically can be dissected into 2 distinct layers - Thin outer (meningeal) layer - Thicker inner (endosteal) - Inner layer envelops oculomotor nerve (CNIII), trochlear nerve (CNIV), ophthalmic (V1) & maxillary (V2) segments of trigeminal nerve - Lateral & medial walls of CS merge inferiorly along lateral margin of sphenoid, just above maxillary nerve (V2) - While V3 invested by contiguous dura, not considered component of CS wall - V2 similar to V3 in regards to CS lateral wall; lies at inferior margin of CS or just outside CS envelope rather than being true component of wall - Lateral wall merges inferiorly & posteriorly with dura covering Meckel cave
  • Medial wall - Consists of upper sellar component & lower sphenoid component - Upper sellar component of medial wall formed by thin dural membrane, typically single cell layer in thickness that separates venous compartment from lateral margin of pituitary gland - Inherent weakness of upper sellar component makes it susceptible to invasion from pituitary tumors - Thicker lower medial wall adherent to carotid sulcus of sphenoid bone
  • Anterior wall - Rectangular in shape extending from optic strut, beneath anterior clinoid process laterally to include SOF - Inferior margin formed by foramen rotundum - Anterior CS merges with venous plexus in SOF
  • Posterior wall - Extends from lateral margin of dorsum sellae to medial aspect of trigeminal impression of PA & superomedial aspect of Meckel cave - Limited inferiorly by junction of PA & body of sphenoid bone at superomedial aspect of petroclival fissure - Dorello canal & CNVI - Small gap that separates PA from clivus near medial & superior tip of PA - Small petrosphenoid ligament of Gruber, crosses from PA tip to base of posterior clinoid process - Contains venous tissue at confluence of posterior CS & petrosal sinuses - CNVI passes from prepontine cistern through Dorello canal to enter CS - Petrolingual ligament (PLL) - Extends from PA to lingula of sphenoid bone - Invariably surrounds dorsal & lateral walls of lacerum segment of ICA - Important surgical landmark that marks point at which ICA lacerum segment transitions to cavernous segment - Also marks inferior & posterior margin of CS
  • Venous communications - Venous tributaries - Superior, inferior ophthalmic veins - Sphenoparietal sinus - Communicate with each other via intercavernous plexus (anterior, posterior, & inferior across sella) & basilar venous plexus (across clivus) - Communicates posteriorly with inferior petrosal sinus, superior petrosal sinus, & basilar venous sinus - Additional communications with veins of pterygoid venous plexus & skull base foramina (foramen ovale, rotundum, & spinosum, carotid canal, & sphenoidal emissary foramen)
  • Meckel cave - Dural outpouching that begins in posterior fossa (porus trigeminus) & extends over petrosphenoid junction into medial & posterior aspect of middle cranial fossa - Contains part of trigeminal nerve, including trigeminal ganglion - Superior, anterior, & medial portions of Meckel cave are immediately adjacent to posterior & lateral aspects of CS - Medial & inferior aspect of Meckel cave is just lateral to ICA as it arises from medial opening of carotid canal & begins to turn vertically & anteriorly into CS - Trigeminal ganglion positioned in anterior & inferior aspect of Meckel cave, divides into 3 divisions: Ophthalmic (V1), maxillary (V2), & mandibular (V3) - Ophthalmic division (V1) extends medially & anteriorly & enters lateral wall of CS - Maxillary division (V2) extends anteriorly, along inferior margin of CS to enter foramen rotundum - Mandibular division (V3) extends inferiorly & laterally through foramen ovale

• Internal Contents

  • CNIII - Pierces roof of CS in oculomotor cistern & gets embedded in lateral wall - Surrounded by thin sleeve of arachnoid & CSF (oculomotor cistern) that travels with nerve for several millimeters to anterior clinoid process
  • CNIV - Also pierces roof of CS, & nerve positioned in lateral wall below CNIII
  • V1 (ophthalmic division of CNV) in lateral wall below CNIV
  • V2 (maxillary division of CNV), most inferior cranial nerve in lateral CS wall
  • V3 (mandibular division of CNV) does notenter CS proper (passes from Meckel cave inferiorly into foramen ovale)
  • CNVIlies within CS proper, next to ICA
  • Sympathetic fibers travel along ICA within CS
  • Cavernous ICA - Bouthillier et al described 7-segment classification system for ICA - Cervical - Petrous - Lacerum - Cavernous - Clinoid - Ophthalmic - Communicating segments - Cavernous segment begins as lacerum segment of ICA passes beneath PLL - Initially ascends & then turns (posterior genu) anteriorly to assume horizontal course through CS - Posterior genu, usual site of origin for meningohypophyseal trunk - Horizontal portion of cavernous ICA lies within carotid sulcus along lateral margin of sphenoid bone - Carotid sulcus occasionally dehiscent, allowing ICA to protrude into sphenoid sinus - Horizontal segment gives rise to inferolateral trunk, which supplies tiny branches to intracavernous cranial nerves & tentorium - Near anterior margin of CS, ICA turns cephalad (anterior genu) & continues medial to anterior clinoid process - Along this anterior vertical course, ICA passes through 2 anatomically distinct dural rings: Proximal dural ring, which forms true roof of CS anteriorly, & distal dural ring - Short vertical clinoid segment medial to anterior clinoid process & corresponds to interdural segment of artery between proximal & distal dural rings

ANATOMY IMAGING ISSUES

• Imaging Recommendations

  • Due to high soft tissue contrast resolution & multiplanar capabilities, MR ± contrast remain imaging modality of choice - Coronal thin-section high-resolution T2 & T1 weighted sequences - Axial & coronal T1 fat-saturated thin-section high-resolution sequence after intravenous gadolinium contrast injection
  • CT angiogram best for identifying pathology of cavernous ICA & for carotid cavernous fistula
  • CT venogram can produce adequate venous-phase contrast enhancement to evaluate for CS thrombosis or thrombophlebitis
  • High-resolution bone CT imaging, complementary in evaluation of erosive or destructive pathologies of central skull base
  • Conventional angiogram often necessary for diagnosis & treatment of direct & indirect carotid cavernous fistulas as well as cavernous carotid aneurysms

• Imaging Pitfalls

  • Enhancement of CS can be asymmetric, especially in arterial phase or early venous phase, & should not be mistaken for pathology
  • Given presence of multiple potentially enhancing structures in & around CS (CS, pituitary, & ICA), small enhancing lesion, such as perineural tumor spread, may be difficult to discriminate
  • Fat can be normally seen anterior in CS near SOF & posterior ICA
  • Air foci in CS can be seen on CT from venous emboli resulting from peripheral IV catheter placement

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Images

Graphics

Axial graphic of sella turcica, as viewed from above, depicts normal sellar and parasellar anatomy. Dura covering right cavernous sinus (CS) is removed to show CNV and CNVI. All cranial nerves are shown in left CS. Mandibular division of CNV does not run through CS but exits from Meckel cave inferiorly to enter foramen ovale. Note CS is not a single venous channel but is extensively septated.

Axial graphic of sella turcica, as viewed from above, depicts normal sellar and parasellar anatomy. Dura covering right cavernous sinus (CS) is removed to show CNV and CNVI. All cranial nerves are shown in left CS. Mandibular division of CNV does not run through CS but exits from Meckel cave inferiorly to enter foramen ovale. Note CS is not a single venous channel but is extensively septated.

Coronal graphic depicts contents of CSs. The following cranial nerves traverse CS within lateral wall of CS, from superior to inferior: Oculomotor (CNIII), trochlear (CNIV), 1st (ophthalmic or V1) and 2nd (maxillary or V2) divisions of trigeminal (CNV) nerves. The only cranial nerve actually within venous sinusoids of CS is abducens nerve (CNVI).

Lateral graphic demonstrates cranial nerve detail in sellar region. CNIII, CNIV, CNV1, and CNV2 are in lateral dural wall of CS. CNVI courses within venous sinusoids of CS, adjacent to internal carotid artery (not shown). Meckel cave is CSF-filled, dural and arachnoid-lined invagination that communicates freely with prepontine cistern. It contains fascicles of trigeminal nerve (CNV) and trigeminal (gasserian) ganglion.

Axial T1 C+ MR

Series of 6 axial contrast-enhanced T1 MR images, presented from inferior to superior through the skull base and CS, demonstrates the right maxillary nerve (V2) passing anteriorly into the foramen rotundum and the left trigeminal ganglion. The mandibular nerve (V3) will exit inferiorly through the foramen ovale (not shown).

The Meckel cave is located posterior, inferior, and lateral relative to the CS. Dura forming the posterior part of the lateral wall of the CS also forms the upper medial 1/3 of the Meckel cave, separating the 2 structures. Note the abducens nerve (CNVI) seen here as a filling defect within the clival venous plexus, just before entering the Dorello canal.

Both abducens nerves are seen coursing through the Dorello canal to enter the posterior CS. The right trigeminal nerve is seen entering the Meckel cave.

Cranial nerves exiting the CS through the superior orbital fissure (SOF) are CNIII, CNIV, CNVI, and the 1st (ophthalmic or V1) division of CNV.

The optic nerve in the optic canal is located anteromedial to the anterior clinoid and superomedial to the SOF. It is separated from the SOF by a thin, bony strut, the "optic strut." The cavernous carotid is posteromedial to the anterior clinoid. Note the origin of the ophthalmic artery from the internal carotid artery, just above the transition from the intracavernous carotid (below) to the intradural carotid (above) segments.

Pituitary infundibulum is seen within the suprasellar cistern posterior to the optic chiasm; avid enhancement seen here is typical. The supraclinoid internal carotid artery (or terminal segment) is seen laterally.

Coronal T2 MR

First of 6 sequential coronal T2 MR images, presented from posterior to anterior, demonstrates the optic tracts within the posterior aspect of the suprasellar cistern and the anterior cerebral and supraclinoid internal carotid arteries.

The posterior optic chiasm and part of the pituitary infundibulum are seen here. Note the internal carotid, middle cerebral, and anterior cerebral arteries. Individual trigeminal nerve rootlets are well demonstrated within the Meckel cave on thin-section imaging.

Image at the level of the optic chiasm within the suprasellar cistern demonstrates normal pituitary gland and regional vascular anatomy. Note the normal location and appearance of the Meckel cave, seen inferior and lateral. The pituitary gland and venous blood within the CS are nearly isointense with each other on T2.

Normal appearances of the anterior pituitary gland, CS, Meckel cave, and suprasellar cistern are shown. The oculomotor nerves (CNIII) and optic nerves (CNII) are well seen. The anterior communicating artery, which connects the 2 anterior cerebral arteries and the left middle cerebral artery genu, are visible.

The most anterior aspect of the suprasellar cistern demonstrates normal optic nerves (CNII), oculomotor nerves (CNIII), cavernous internal carotid arteries, and the anterior cerebral artery within the anterior interhemispheric fissure.

The anterior clinoid processes seen here form the anterolateral boundaries of the sella turcica. Note the normal optic nerves, located medial to the anterior clinoids, and the anterior genu of the cavernous internal carotid artery on the left.

Coronal T1 C+ MR

First of 6 sequential contrast-enhanced T1 MR images through the sella, presented from posterior to anterior, demonstrates details of the Meckel cave. The mandibular (V3) division of the trigeminal nerve is seen inferior to the normally enhancing gasserian ganglion.

The pituitary infundibulum insertion into the gland is well seen. Note the mandibular nerve (3rd division of trigeminal nerve or V3), best seen on the right as it exits through foramen ovale, entering the high masticator space. It is easy to see how extracranial tumors may gain access to the intracranial compartment without destroying the skull base, either through direct extension or via perineural spread.

The left foramen ovale is well seen. Note the 3rd and 6th cranial nerves within the CS. All of the cranial nerves are not well seen on this image.

This image demonstrates the oculomotor, abducens, and maxillary nerves. The pituitary gland enhances less strongly than venous blood in the CS.

Normal cranial nerves traversing the CS from superior to inferior include the oculomotor nerve, trochlear nerve, abducens nerve, ophthalmic nerve (V1), and maxillary nerve (V2). The 4th cranial nerve (trochlear) is small and difficult to visualize but is normally located in the lateral CS between the oculomotor and trigeminal nerves, lateral to the abducens.

The oculomotor nerve is again well seen in the anterior CS before it traverses the SOF. The vidian canal, which contains the vidian artery and nerve, is seen in the sphenoid bone. Note the optic nerves medial to the anterior clinoids before entering the optic canals.

Anatomic-Pathologic Correlation

Coronal T2 MR at the level of the CS demonstrates pituitary macroadenoma in the sella with suprasellar extension invading into the right CS. There is encasement of the right cavernous carotid with preserved flow void. There is significant mass effect on the optic apparatus. Note the normal left CS.

Axial MR performed in the same patient with bacterial sinusitis and bilateral CS thrombosis is shown. The flow voids in the internal carotid arteries are less distinct but present. The CS walls enhance normally, but the internal venous compartments of the CSs fail to enhance bilaterally due to venous sinus thrombosis.

Axial 3D time-of-flight MRA demonstrates a saccular aneurysm arising from posterior genu of right cavernous carotid projecting medially with mild mass effect on the pituitary gland. Note normal left cavernous carotid flow-related signal.

Additional Images

Axial MR performed in the same patient with bacterial sinusitis and bilateral CS thrombosis is shown. The flow voids in the internal carotid arteries are less distinct but present. The CS walls enhance normally, but the internal venous compartments of the CSs fail to enhance bilaterally due to venous sinus thrombosis.

Bacterial sinusitis complicated by bilateral CS thrombosis is shown. Coronal MR through the CSs demonstrates complete opacification of the sphenoid sinus secondary to bacterial sinusitis. The lateral walls and roofs of the CSs enhance normally. However, there is conspicuous lack of enhancement in the central areas of CSs bilaterally. Normal flow voids (dark areas) are identified in the internal carotid arteries bilaterally.

Lateral graphic of normal pituitary: The adenohypophysis is comprised of the pars tuberalis, pars intermedia, and pars distalis. The neurohypophysis is comprised of the median eminence of hypothalamus, infundibulum, and pars nervosa. Periosteal dural layer covers the sellar floor.

Axial CECT in a patient with bacterial facial cellulitis and bilateral CS thrombosis is shown. The superior ophthalmic veins show filling defects bilaterally, consistent with thrombosis. The lateral walls of the CSs enhance normally. However, on this delayed venous-phase image, the CSs demonstrate lack of significant internal enhancement consistent with bilateral thrombosis.