CAVERNOUS SINUS

CAVERNOUS SINUSSurgical anatomy and Cavernous Sinus ThrombosisDr. Mukhallat Qazi1st Year PostgraduateDepartment of OMFSOVERVIEW Introduction Development AnatomyStructures withinStructures aroundTributaries

2Cavernous Sinus Thrombosis Clinical Presentation Danger Area of the Face Investigations Neuroradiology Complications Treatment

INTRODUCTION3The space or compartment commonly called the cavernous sinus is a veritable anatomical jewel box containing more significant structures than any other comparable space outside the brain itself. (Parkinson 1990)

Cavernous+ SinusCavernous- Cavern: A large cave or chamber in a cave specific type of cave, naturally formed in soluble rock with the ability to grow speleothems

Sinus- Medieval Latin: A hollow curve or cavity in the bodyCalled Circular sinus" by Ridley (1695)Wilson(1732)Named this structure CAVERNOUS SINUS Due to its spongious structure which seemed to be formed by numerous fibres and connective tissue septae4

Dural SinusesLie between the endosteal and meningeal layers of dura materAre lined by endothelium, firm collagenous tissueHave no valvesWalls are devoid of muscular tissueNumerous lacunes and trabeculae56

DEVELOPMENTPadget (1956)Cavernous sinus Plexiform extension of prootic sinus and ventral myelencephalic veinSuperior ophthalmic v Primitive maxillary v as it drains into the prootic sinus, and develops into the superior ophthalmic vein which drains directly into the cavernous sinus.778Knosp (1987)20% of fetal skull bases- SMCV drains into the Cavernous Sinus60% of fetal skull bases- SPS and Cavernous Sinus show a connectionHence developmental basis for varied pattern of venous tributaries and drainage

9Schematic drawings of the developmental anatomy of cavernous and para-cavernous venous structures in the embryonic stage.

S. Tanoue et al. AJNR Am J Neuroradiol 2006;27:1083-10892006 by American Society of NeuroradiologySchematic drawings of the developmental anatomy of cavernous and para-cavernous venous structures in the embryonic stage. SSS indicates superior sagittal sinus; PTS, primitive tentorial sinus; PS, prootic sinus; PMS, primitive maxillary sinus; and IPS, inferior petrosal sinus.A, Lateral view; B, axial view. In an 8-week embryo, cerebral venous structures develop from primitive dural plexuses surrounding primitive cerebral vesicles. The plexuses fuse to form venous sinuses and cortical veins. Two major primitive sinuses, the primitive tentorial sinus and the prootic sinus, contribute to the development of cavernous sinus and para-cavernous sinus veins. The primitive SMCV is connected with the transverse sinus via the primitive tentorial sinus.C, In a 12-week embryo, after several weeks, the primitive SMCV is elongated and develops anteromedially to form the SMCV as a development of the cerebral hemisphere. The prootic sinus contributes to form the superior ophthalmic vein, the cavernous sinus, and the foramen ovale venous plexus.D, Axial view; E, lateral view. In a developed embryo, the SMCV makes further anteromedial development in the prenatal stage; however, in many patients, there is no direct connection between the SMCV and the cavernous sinus. Secondary anastomosis after birth may form a connection between the SMCV and the cavernous sinus, and the connection to the primitive tentorial sinus subsequently degenerates.ANATOMY11

Number 2, Paired Dimensions Length 20mm Width 09mmLocation Middle Cranial Fossa Either side of body of sphenoid Extent From Superior Orbital Fissure to the Petrous apex of Temporal bone Shape Triangular in cross section, Boat shaped12

STRUCTURES WITHIN.. CONTENTS1314

Anatomical Relations1516

The CS in parasagittal views. A. Osteology. OF, optic foramen; SOF, superior orbital fissure; FR, foramen rotundum; CC, carotid canal; Se, sella turcica; Ac, anterior clinoid process; Pc, posterior clinoid process. Note that the optic canal runs medial to the Ac. B. Venous plexus. The plexus consists of large-caliber fenestrated venous spaces that may communicate with the contralateral CS through foramina in the medial bony wall. II, optic nerve; PG, pituitary gland. C. The carotid siphon and sympathetic plexus. The ophthalmic artery is given off as the first major intracranial branch of the internal carotid artery just as it exits the roof of the CS. Smaller meningeal branches are not shown. The sympathetic nerve supply travels as a neural plexus (not shown) around the carotid artery, entering the orbit with the ophthalmic artery and through the superior orbital fissure. ICA, internal carotid artery (carotid siphon); OA, ophthalmic artery. D. Cranial nerve supply. All cranial nerves except the abducens travel through the CS tightly adherent to the lateral dural wall. The abducens nerve has an unpredictable course through the venous plexus but is usually adherent at least in part to the carotid siphon. Note how the abducens nerve travels vertically over the petrous ridge and becomes tethered by Gruber's ligament just before entering the CS. This tethering predisposes the abducens nerve to deceleration injury in head trauma. The maxillary division is closely associated, but outside, the CS. The parasympathetic nerve supply to the globe travels within the oculomotor nerve. III, oculomotor nerve; IV, trochlear nerve; V-1, ophthalmic division (trigeminal nerve); V-2, maxillary division; V-3, mandibular division; VI, abducens nerve. E. The lateral dural wall. (Modified from Zide BM, Jelks GW: Surgical Anatomy of the Orbit, p 8. New York, Raven Press, 1985) 16Osseous Relations171718

ANTERIOROptic strutAnterior clinoid processLesser wing of sphenoidMEDIALCarotico-clinoid foramenMiddle clinoid processPituitary fossaBody of sphenoidCarotid sulcusLATERALGreater wing of sphenoidForamina (rotundum, ovale, spinosum)POSTERIORPosterior Cliniod ProcessDorsum SellaPetrous ApexTrigeminal Impression

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Ant Clin Process Carotid sulcus- Course of ICA Optic Strut- Lateral and inferior wall of the optic canalThese three structures almost encircle the ICA CLINICAL SIGNIFICANCE OF OSSEOUS RELATIONS

In surgically exploring cavernous sinus, an initial step is to unlock the contents of the sinus from the bony confines.This step includes unroofing and mobilizing the optic nerve, and then removing anterior clinoid process.This phase can be performed in an extradural or intradural fashion.

DURAL RELATIONS

Floor formed by single periosteal layer of dura, supero--medially it continues with dura of sella turcica.2122

ROOFAnterior extension of the Tentorium CerebelliLateral extension of Diaphragma SellaRoofAnteriorDura lining the lower margin of Ant Clin Process- Anterior Clinoidal FoldPosterior Posterior Clinoidal FoldPatch of dura- Occulomotor triangle

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Posterior WallLower margin shared with basilar sinus, pierced by Abducens nUpper edge- posterior petroclinoidal foldInferomedial Triangles are seen2324

25Lateral wall

Dura propria of Uncus of the temporal lobe

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Upper and lower dural rings

The segment of the internal carotid artery located between the upper and lower dural rings, which is exposed by removing the anterior clinoid process, is referred to as the clinoid segment.The dura lining and extending medially from the upper surface of the anteriorclinoid forms the lateral part of a dural ring, referred to as the upper or distal ring, which defines the upper margin of the carotids clinoid segment Further medially, the dura forming the upper ring blends into the diaphragma sellae.27NEURAL RELATIONSCranial nerves III to VI are closely related to cavernous sinus.

Oculomotor Nerve29

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Trochlear Nerve31Ophthalmic Nerve32

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Abducens Nerve34

Exit through the SOF and supplies the Superior Oblique mClinical SignificanceCranial nerve palsy is the most common manifestation of pathologic processes involving the cavernous sinus.

Diplopia, Sixth nerve palsy with Horners Syndrome, impaired visual acuity may suggest cavernous sinus lesions.

Most cavernous sinus explorations are for benign disease with the goal of preserving and improving cranial nerve function.

Exploration of cavernous sinus usually follows mobilization of lateral wall and entry through one or more of the various triangles formed by these cranial nerves and dural folds.

35Horner syndrome (Horners syndrome) results from an interruption of the sympathetic nerve supply to the eye and is characterized by the classic triad of miosis (ie, constricted pupil), partial ptosis, and loss of hemifacial sweating (ie, anhidrosis)35Anatomic Triangles

Vascular Relations37Arterial RelationsInternal Carotid Artery and its anatomically divided course-Petrous CavernousIntracranialVenous RelationsAfferent TributariesEfferent DrainageInternal carotid artery38

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Petrous part40

ICA ascends to reach itsbifurcation into the middle and anterior cerebralartery (MCA and ACA) to form the circle of Willis4041

42Veinous relationsTributaries (afferent veins): Superior ophthalmic vein (SOV) Inferior ophthalmic vein (IOV)Central retinal vein Superficial middle cerebral vein (SMCV) Uncal vein (UV) Sphenoparietal sinus (SPPS) Meningeal veins43

Drainage (efferent veins):

Foramen ovale plexus (FOP)Vein of the foramen rotundumPterygoid plexus (PP)Internal jugular vein (IJV)Facial vein (FV)Angular vein (AV)Retromandibular veinSupraorbital veinFrontal vein (FrV)44

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Basilar plexus (BP)Sphenoparietal sinus (SPPS)Sigmoid sinus (SS) Superior petrosal sinus (SPS)Inferior petrosal sinus (IPS)Intercavernous sinus (ICS)Jugular bulb (JB)Middle temporal vein (MTV)46

COMMUNICATIONS OF CAVERNOUS SINUSVenous blood from the brain flows via the superficial( cortical) and the deep cerebral veins into the venous (dural) sinuses. There are numerous connections between the cortical veins and dural sinuses. This facilitates the spread of thrombus infection between these vessels. Also allows opening of collateral draining vessels in the event of an occlusion.Summary of communicationThe cavernous sinuses receive blood from cerebral veins the ophthalmic veins (from the orbit) emissary veins (from the pterygoid plexus of veins in the infratemporal fossa). These connections provide pathways for infections to pass from extracranial sites into intracranial locations. In addition, because structures pass through the cavernous sinuses and are located in the walls of these sinuses, they are vulnerable to injury due to inflammation.

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Clinical significance of Vascular RelationsLesion of surgical importance affecting ICA range from aneurysm to carotid-cavernous fistulae.After removal of anterior clinoid process, mobilization of anterior loop of ICA can be done for clipping of aneurysm.Treatment of aneurysm ranges from simple observation to balloon occlusion and trapping of the lesion with or without bypass.Conditions affecting Cavernous sinus and its contents Midbrain Infection Cavernous Sinus Thrombosis Orbital FracturePetrous Bone Fracture (Temporal bone Fracture ) Internal Carotid Artery Aneurysm MastoiditisIncreased Intracranial Pressure

Clinical and applied aspects It is the only anatomic location in the body in which an artery travels completely through a venous structure. If the internal carotid artery ruptures within the cavernous sinus, an atriovenous fistula is created.Cavernous sinus syndrome may result from mass effect from a tumour or CST and cause opthalmoplegia from compression of the oculomotor nerve, trochlear nerve, and abducens nerve, ophthalmic sensory loss from compression of the ophthalmic nerve, and maxillary sensory loss from compression of the maxillary nerve.Cavernous sinus thrombosis is the formation of a blood clot within the cavernous sinus. Emissary Veins53Emissary Syn. ambassadorFrom skull veins to external veinsImportance- to maintain intracranial and extracranial venous pressure at an equilibrium, valve-less to ensure the same.May carry Infected thrombus from extracranial to intracranial circulation

The emissary veins are valveless veins which normally drain from the dural venous sinuses into veins that lie outside the skull (external veins) Usually, the body takes the help of muscle contraction to pump blood up the veins. So, when the muscles contract, they squeeze blood up in the veins. When this happens, there should be mechanism to prevent blood from going back. This is where the valves come in to play. They prevent backward flow of blood. Veins have valves because they contain blood that flows at a low pressure while arteries do not have valves because they contain blood that flows at high pressure. Valves prevent the back flow of blood which would normally occur in the veins as a result of the low pressure compared to arteries where the heart provides the pressure needed to send blood through the system.

53CAVERNOUS SINUS THROMBOSISThrombosis of the cavernous sinus is one of the most dramatic of neuro-ophthalmic conditions. Within a short period, a swollen orbit, limited ocular motility and impaired vision develop, and may progress to a life threatening conditionRapid diagnosis and therapeutic action are required. Morbidity is high, and outcome cannot be certain.54EpidemiologyFrequency: In the US occurrence of CST has always been low, with only a few hundred case reports in the medical literature. The majority of these date from before the modern antibiotic era. One review of the English language found only 88 cases from 1940 -1988.Mortality/ morbidity: Prior to the advent of affective antimicrobial agents, the mortality rate from CST was effectively 100%. Typically death is due to sepsis or central nervous system infection. With aggressive management the mortality rate is now less than 30%. Morbidity however remains high and complete recovery is rare. Roughly one sixth of patients are left with some degree of visual impairment and one half have cranial nerve deficits. Race : no predilection Sex: no predilection Age : all ages are affected with a mean of 22 years

55Causes of cavernous sinus thrombosis56Danger area of the face57

Odontogenic origin of CVTCST is one of the major complications resulting from infection of teeth or surrounding structures in the upper and lower jaws.Extraction of mandibular molars (Buccal Space) and maxillary anterior teeth (Infraorbital Space) in the presence of acute infection, usually staphylococcal, can cause this condition.The infection can spread by Direct Hematogenous(metastatic )

Infra Temporal Space Pterygoid plexus which receives tributaries from transverse facial vein, which passes through buccal space.Buccal space infections that erode the transverse facial vein may cause ascending thrombophlebitis of pterygoid venous plexus posterior routeEmissary veins connect pterygoid plexus to the cavernous sinus through for. of vesalius, ovale and lacerumAngular vein ascending thrombophlebitis as a result of infraorbital space infection Ophthalmic vein Anterior route58Direct SpreadSpread by direct extension via the infratemporal space through the cranial wall By way of pterygoid plexus and emissary veins, against the usual flow. This is possible because of the anatomic anomaly of the absence of valves in the angular, facial and ophthalmic veins.Staphylococcus aureus More often from upper teeth than lower teeth.

Heamatogenous SpreadMore often from lower teeth than upper teethReverse of direct spread.Streptococcus (haemolytic, non-hemolytic, or viridans) usually associated

59Method of spread into cranial cavity

PtosisProptosisChemosisStarts as unilateral may prgress to contralateralSystemicToxic appearance, headache nausea giddiness vomiting and somnolenceFeverProgression- signs of meningitis, brain abscess 6162

The clinical symptoms of CST vary depending upon the anatomical structures involved. The most common symptoms are fever, proptosis, chemosis, and external ophthalmoplegia. Ophthalmoplegia is extraocular muscle weakness that results (in CST) when cranial nerves III, IV, and/or VI are damaged due to their passage through the cavernous sinus. Other symptoms of lethargy, headache, periorbital swelling, papilledema, and venous engorgement occur in 50%-80% of patients. Decreased visual acuity, sluggish/dilated pupil, periorbital sensory loss, and decreased corneal reflex are less frequent symptoms that occur in