Radiological Imaging of the cavernous sinus lesions

Dr/ ABD ALLAH NAZEER. MD.

Cavernous Sinus AnatomyPaired collection of thin walled veins between the endosteal and meningeal dural layers located at the center of the head which drains intracranial blood

Anterior Border = Superior orbital fissurePosterior Border = Petroclinoid fold and Clivus dura matterInferolateral Border =Inner middle cranial fossaLateral Border = Outer dural meningeal layer with deeper inner nerve containing layerMedial Border = Sella turcica.

Venous FlowReceives venous tributaries from the superior and inferior ophthalmic veins and superficial cortical veinsDrains into the superior and inferior petrosal sinusesConnected to the venous basilar plexus posteriorly

• Nerves– Lateral wall, superior to inferior

• CN III: Occulomotor nerve• CN IV: Trochlear nerve• CN V1: Ophthalmic nerve, the V1

branch of the trigeminal nerve • CN V2: Maxillary nerve, the V2

branch of CN V– Paralleling internal carotid

artery• CN VI: Abducents nerve

• Artery– Internal carotid artery• Bends as the

cavernous, C4 segment• Bifurcates

– Meningohypophyseal trunk & Inferolateral trunk

Cavernous Sinus TumorsMost common etiology of cavernous sinus syndromePrimary tumors

SchwannomaNeurofibromaMeningiomaHemangioma Lymphoma

Secondary involvement/Metastatic disease Pituitary AdenomaNasopharyngeal carcinomaPerineural spread of tumor through neural foraminaBase of skull tumor

ChondrosarcomaOsteosarcoma

Pituitary adenomaSix to 10% of pituitary adenomas invade the cavernous sinus, and represents its most frequent lesion. It is an intrasellar process with lateral extension to the cavernous sinus, in opposition to other diseases originating from the CS. These invasive pituitary adenomas are associated with more surgical mortality and morbidity. Macroadenomas (>1 cm) appear hypointense on T1-weighted image (WI) and hyperintense on T2-wi. They enhance after gadolinium administration, but less than normal pituitary tissue. Invasion of the cavernous sinus is secondary to the perforation of its medial wall, and is very likely if the lateral intercarotid line is crossed or if the encasement of the intracavernous ICA by the tumor is greater than or equal to 67%. Invasion may be more extended laterally after perforation of the lateral wall of the cavernous sinus. In general, they displace the ICA without narrowing.

Pituitary adenoma. Coronal T2-wi (a) and coronal enhanced T1-wi (b) showing an enhancing pituitary adenoma (arrows), appearing hyperintense on T2-wi and invading the left cavernous sinus with an encasement of the left internal carotid artery. Note the displacement of the arteries by the mass (stars) without stenosis.

Large enhancing pituitary mass extending to the right cavernous sinus and encasing the right ICA.

Meningioma.Meningiomas became up to 18% of all intracranial tumors. They may arise from a suprasellar or parasellar location. Suprasellar meningiomas commonly arise from the diaphragm sellae or tuberculum sellae, and vision defects caused by compression of the optic chiasm are common clinical findings. Large meningiomas originating along the planum sphenoidale or greater wing of the sphenoid bone may extend into the suprasellar cistern or parasellar regions. These tumors may be entirely parasellar if they originate from the dural wall of the cavernous sinus. Meningiomas are generally isointense relative to cortical gray matter on T1- and T2- weighted images.

Meningioma: axial T2-wi (a) and T1-wi after contrast (b) showing a left cavernous sinus mass (white arrows) slightly hypointense on T2 sequence with strong and homogeneous enhancement. This lesion presents a dural tail anteriorly and posteriorly and totally encases the intracavernous left internal carotid artery, which is narrowed (black arrow).

T2 isointense left cavernous sinus meningioma with narrowing of the left ICA

Intracranial solitary fibrous tumor. Axial T2-wi (a) and coronal enhanced T1-wi (b) of a large extra-axial mass (arrows) of the right skull base extending to the right cavernous sinus with an important mass effect on the right temporal lobe and mesencephalon. This lesion shows a strong enhancement after contrast (b), and a mixed signal on T2-wi (a) with intermediate-high and low signal intensity.

Intracranial solitary fibrous tumor: It is a rare mesenchymal tumor, usually extra-axial. It appears isointense on T1-wi with strong and heterogeneous enhancement. The characteristic finding is a patchy appearance with high and low signal areas on T2-WI

Schwannoma Although vestibular schwannomas represent about 95% of intracranial schwannomas, neural sheath tumors can develop in all the other nerves of the cerebello-pontine angle, especially trigeminal and facial nerves but also IX to XII nerves. Neuroimaging features are the same as for vestibular schwannomas, including possible cystic or hemorrhagic components. Trigeminal schwannomas represent about 0.2% of all intracranial tumors and about 2%-3% of all intracranial schwannomas, and they may arise in any segment of the nerve; however, the majority develops at the gasserian ganglion. They may grow primarily in the parasellar region or extend posteriorly through the porus trigeminus into the posterior fossa. Tumor extension into the pterygoid fossa or paranasal sinuses occurs in 10% of cases. The pressure exerted by the tumor leads to erosion of the underlying bone and enlargement of the foramen ovale, foramen rotundum, or the superior orbital fissure, which is better appreciated on thin-section coronal-CT scans. Trigeminal schwannomas typically follow the course of the fifth cranial nerve and have a dumbbell-shaped configuration. They are smoothly marginated tumors and are usually isointense comparing to gray matter on T1WI and hyperintense on T2WI. Small tumors are homogeneous; large tumors can have heterogeneous signal intensity due to degenerative changes, including cyst formation and fatty degeneration.

Trigeminal Nerve Schwannoma

Schwannoma: axial enhanced T1-wi at the level of the cavernous sinus showing a well defined and enhanced mass lesions located bilaterally along the cisternal portion of the trigeminal nerves (arrows); the left one extending to the cavernous sinus and Meckel's cavum. Theses lesions suggest schwannomas of the trigeminal nerves and can be seen in type II neurofibromatosis. Note the enhanced extra-axial left temporo-polar lesion corresponding to a meningioma.

Neurinoma of the trigeminal nerve (T1-weighted sequences and T2).

Neurinoma of the Meckel´s cave.

Plexiform Neurofibromas.Most commonly involve the trigeminal nerve, typically the first and second branchesSeen in 30% of patients with neurofibromatosis type 1 but are extremely rare outside this diseaseImaging:

Tortuous or fusiform enlargement of the nerves that exhibit heterogeneous signal intensityNeurofibromas are less likely to extend to the Meckel cave unlike schwannomas

Plexiform neurinoma

Plexiform Neurofibromas.

Multiple plexiform neurofibromas in a patient with NF-1 with one of the neurofibromas extending into the right cavernous sinus

Chordoma and Chondrosarcoma Chondromatous tumors develop from embryonic cartilaginous remnants enclosed in the bones of the skull base. They often arise from the petrooccipital or sphenooccipital synchondrosis and destroy the adjacent bones. Chondromatous tumors can be hypoattenuating at CT, possibly with a marginal high-attenuation area due to a dense matrix of hyaline cartilage or massive calcification. Lytic bone erosion may be seen. At MR imaging, the tumor is hypointense on T1- weighted images and heterogeneously hyperintense on T2-weighted images; it enhances poorly due to its hypovascularity.

Chondrosarcoma: large mass localized on the right petroclival fissure invading the right cavernous sinus and extending to the posterior fossa with mass effect on the pons. CT shows stippled calcifications and petrous apex erosion (a). This mass is strongly hyperintense on T2-wi (b), and shows heterogeneous enhancement after contrast (c).

Chordoma: mass centered on the clivus and the right cavernous sinus, heterogeneously hyperintense on T2-wi. (a), hypo- to isointense on T1-wi with an heterogeneous enhancement after contrast (b) corresponding to a chordoma.

Chondroma.

HemangiomaIt's a vascular lesion rarely located in the CS. Differential diagnoses include meningioma and schwannoma. Hemangioma appears isodense or slightly hyperdense compared with surrounding structures on CT, and does not contain calcifications. The characteristic imaging findings are a high signal in T2-wi and a progressive and strong centripetal enhancement. 

Cavernous hemangiomas. A, Axial post contrast T1-weighted image shows a large and homogeneously enhancing mass arising from the lateral wall of the left CS. B, Axial post contrast T1-weighted image in a different cavernoma, which shows inhomogeneous contrast enhancement but also arises from the lateral wall of the CS, pushing the ICA (arrow) medially. When a mass arises in the lateral wall of a CS, the most important differential diagnosis is that of meningioma versus cavernoma.

Hemangioma: hemangioma appears as a very well delineated lesion of the left cavernous sinus (white arrows), hyperintense on T2-wi (a), associated with progressive and centripetal enhancement (black arrow: b, c).

Juvenile angiofibroma. Axial post contrast T1-weighted image shows a very large tumor involving both CSs and surrounding the ICAs (arrows). The mass extends into the sella, paranasal sinuses, right middle cranial fossa, and both orbits. Note flow voids (arrowheads) due to enlarged blood vessels.

Metastasis: sagittal enhanced T1-wi (a) showing melanoma metastases appearing as enhanced lesions at the level of the pons (black arrow) and the left third cranial nerve (dotted arrow). Note also the heterogeneously enhanced mass of the orbital ceiling (white arrow) extending to the optic apex and cavernous sinus (black star). Axial CT with bone filter (b) showing a widening of the optical foramen and a destruction of the left anterior clinoid process (circle).

Cavernous sinus metastasis: Metastases are infrequent and secondary to perineural or hematogeneous extension, from head and neck cancer or distant primary malignancy.

Leukemia: coronal T2-wi (a) and T1-wi after contrast (b) showing a insular lesion of the left cavernous sinus (white star), hypointense on T2-wi in comparison with the right cavernous sinus (black star). The lesion encases the intracavernous carotid artery without narrowing it.

Leukemia/lymphoma: They usually involve the CS by direct extension from the nasopharyngeal structures, or by hematogeneous dissemination. They are enhancing masses with T2-low signal intensity and restricted diffusion. An infiltration of the skull base bone and an encasement without constriction of the carotid artery can be seen

Nasopharyngeal carcinoma: nasopharyngeal carcinoma invading both cavernous sinuses with carotid encasement and mass effect on the pons. The tumor appears with an intermediate signal on T2-WI (a) and heterogeneous enhancement on T1-wi after contrast (b).

Nasopharyngeal carcinoma: It can involve the CS by direct skull base invasion, through the foramen lacerum, or along the branches V2 and V3 of trigeminal nerve. The tumor appears hypointense on T2-wi, hypo- to isointense on T1-wi and enhances after contrast. The perineural spread is depicted by an enlarged and enhanced nerve associated with an enlargement of its foramina

Left nasopharyngeal mass with extension in the left cavernous sinus.

Aneurysms The diagnosis of aneurysms is critically important in a sellar region evaluation. The arteries in the Willis´ polygon, which surrounds the sella turcica, are the most frequent locations of intracranial aneurysms. A round lesion with an internal signal void on spin echo MRI, especially on those acquired with T2WI is a classic feature of an aneurysm with rapid internal blood flow. However, partially thrombosed aneurysms appear as well demarcated round parasellar or intra-sellar lesions with internal T1WI hyperintensity and characteristic heterogeneous T2WI hypointensity, findings that indicate intra-aneurysmal clotting. Because a giant aneurysm with partial internal clotting may mimic a solid destructive tumor of the skull base, MR angiography or conventional angiography should be performed in cases with these features before biopsy is considered. The finding of a residual patent lumen on images helps confirm the diagnosis of aneurysm.

Aneurysm: axial T2-wi (a) shows a heterogeneous and enlarged right cavernous sinus with a multilayer appearance (black arrows) corresponding to a giant intracavernous aneurysm. Note the mass effect on the right temporal lobe. See also the 3D volume rendering showing the aneurysm (b).

Cavernous ICA Aneurysm.

Right posterior communicating artery aneurysm digital angiography and MR.

Carotid-cavernous fistula (CCF)CCF is a traumatic or spontaneous abnormal communication between the cavernous sinus and the ICA or the meningeal arterial branches of the CS. CCF can be a direct communication between cavernous ICA and the cavernous sinus (type A) and is almost always caused by a traumatism or less frequently by a ruptured ICA aneurysm. Indirect CCF (type B, C and D) are dural shunts between the CS and the meningeal branches of the cavernous ICA and/or external carotid artery. On enhanced CT, an enlarged cavernous sinus associated with a dilated superior ophthalmic vein and uni- or bilateral proptosis can be seen. On MR imaging, flow voids within the cavernous sinus and hyperintensity on arterial 3D TOF suggest the diagnosis

Enlarged right superior ophthalmic vein with early arterial enhancement of the right cavernous sinus suggestive of carotid cavernous fistula

Carotid-Cavernous (C-C) Fistula.

Carotid-cavernous fistula: axial T2-wi (a) of a carotid-cavernous fistula appearing as a heterogeneous signal with flow voids of the right cavernous sinus (black arrows). Note the dilatation of the superior ophthalmic vein (dotted arrow) and the carotid-cavernous fistula (white arrow) on an arterial TOF of another patient with a carotid-cavernous fistula (b).

Intracavernous aneurysms. A, Axial T2-weighted image shows a left intracavernous ICA (A) aneurysm. Note flow artifacts (arrow) confirming the pulsatile nature of the lesions. B, Coronal postcontrast maximum-intensity image from a CT angiogram in the same patient shows the left intracavernous aneurysm.

CS thrombosis. A, Coronal post contrast T1-weighted image shows an enlarged and inhomogeneous-appearing right CS that contains areas of low signal intensity (arrow) compatible with clot. B, Coronal post contrast T1-weighted image in a different patient shows a large nonenhancing clot expanding the left CS. The ipsilateral ICA is slightly narrowed.

Venous thrombosis of the CS might be related to loco-regional infection spreading from sinonasal cavities and the mastoid. It appears as a non-fatty defect of an enlarged cavernous sinus. The superior ophthalmic vein may be dilated.

Cavernous Sinus Thrombosis:

Acute fulminant invasive mucormysosis with sphenoid sinusitis complicated by acute cavernous sinus thrombosis

Venous thrombosis: bilaterally heterogeneous and enlarged cavernous sinus on T2-wi (a), containing low signal areas on enhanced T1-wi suggesting clots (blacks arrows: b).

Cavernous Sinus Thrombophlebitis.

Enlarged non-enhancing left superior ophthalmic vein (compared with right).Enlarged left cavernous sinus with subtle central hypointensity.Enlarged extra-ocular muscles.

Lemierre syndrome: enhanced axial CT (a, b) showing a left heterogeneous and irregular nasopharyngeal thickening (white arrow). Note also a lack of opacification of the left internal jugular vein compatible with a thrombosis (black arrow) associated with narrowing of the intracavernous internal carotid artery (white arrow: c) well depicted on a 3D reconstruction of the MR angiogram.

Lemierre syndrome includes an internal jugular vein (IJV) septic thrombosis caused by an oropharyngeal infection and septic metastasis. The thrombophlebitis can also be located in the cavernous sinus. Enhanced CT is the preferred tool to diagnose IJV thrombosis. MRI is useful to depict cavernous sinus involvement.

Tolosa Hunt syndrome (THS)THS is a non-specific granulomatous inflammation located in the orbital apex and extending to the cavernous sinus. THS can be bilateral in 5% of the patients. It responds strongly to systemic corticosteroid. It appears as a soft tissue mass, isointense to gray matter on T1-wi. It shows a variable signal on T2-wi and moderate to intense contrast enhancement. The cavernous ICA can be narrowed by the inflammatory process

Tolosa Hunt syndrome: axial (a) and coronal (b) T2-wi, sagittal (c) enhanced CT, showing a insular hypointense enlargement of the left cavernous sinus (arrows) with an enhancement and an extension to the orbital apex (star on image c). These findings are consistent with a Tolosa Hunt syndrome.

Tolosa-Hunt Syndrome

T2 iso-hypointense signal in the left cavernous sinus with enhancementEnhancement is also seen in the left superior orbital fissure

Epidermoid cystCS epidermoid cysts are rare and can involve it in three different ways; an extracavernous epidermoid cyst can invade and compress the CS. It can arise from the lateral dural wall of the CS. Finally, it can be located inside the CS. They appear hypodense on CT. The main features are a heterogeneous hyper signal on FLAIR and high resolution T2 imaging, and high signal intensity on diffusion WI. They show no enhancement .

Epidermoid cyst: hypodense lesion (a) of the left cavernous sinus on CT, with high signal intensity on diffusion WI(b) and heterogeneous hyperintensity on high resolution T2-wi (c).

Normal fat deposits. Axial noncontrast CT scan shows normal and incidentally found deposits of fat (arrowheads) in the posterior CSs. These deposits may be seen in obese individuals, those taking corticosteroids, or those with Cushing syndrome. In the absence of these conditions, they have no significance.

Fat deposits: Normal fatty areas can be found within the cavernous sinus. In some specific conditions, these fat deposits can be larger as seen in patients receiving corticosteroids, in Cushing syndrome and obese people.

Fungal infection. A, Coronal postcontrast T1-weighted image shows involvement by aspergillosis of the mucosa in the left sphenoid sinus (white arrow), which extends laterally and has resulted in thrombosis of the adjacent CS (black arrow). The intracavernous ICA (arrowhead) is narrowed, and its walls are significantly thickened. B, In a different patient, an axial postcontrast T1-weighted image shows enhancing mucosa in the right sphenoid sinus with enhancing soft tissues in the ipsilateral CS (including the Meckel cave), with narrowing of the ICA and significant thickening of its walls.

MRI revealing a mass in the right cavernous sinus, extended to the anterior cranial fossa and the superior orbital fissure with strong enhancement (arrows).

Thank You.