Findings

Etiologic classification of cavernous sinus lesions.

Meningioma (Fig. 2)

Meningiomas are the most common lesions to involve the cavernous sinus, arising from the dura of the cavernous sinus or from the adjacent dura in petroclival region, sphenoid ridge, or clinoid process with extension to the cavernous sinus. They can be exophytic, projecting laterally from the lateral dura, growing in between the two dural layers of the lateral wall in the “interdural plane” or invading the cavernous sinus proper.

The dural tail sign and hyperostosis of adjacent bone, if depicted, can provide a clue to diagnosis. Luminal narrowing of the ICA can be seen if it is encased by tumor. The cellular nature of these tumors manifests as hyperattenuation on CT.

Schwannoma (Fig. 3, 4 and 5)

Schwannomas are benign nerve sheath tumors arising from Schwann cells. Cavernous sinus schwannomas most commonly arise from the trigeminal nerve.

These lesions tend to have an ovoid shape when they are restricted to the cavernous sinus but assume a classic dumbbell shape when they extend into the posterior cranial fossa, the orbit, or the infratemporal fossa. MR FIESTA images are useful to directly depict the cranial nerve of origin.

Diagnostic clue: Heterogeneity with cystic spaces and haemorrhage.

Cavernous Hemangioma (Fig. 6 and 7)

Cavernous hemangiomas are not true neoplasms and are better described as vascular malformations. Establishing the diagnosis of cavernous hemangioma before surgery is of paramount importance, because these tumors are notorious for causing profuse and often uncontrollable intraoperative hemorrhage

Diagnostic clue: Flow voids. DSA may show hypertrophic branches from the ICA and the ECA. Dynamic contrast enhanced T1-weighted MR images show characteristic progressive “fill-in” of contrast agent, with intense homogeneous enhancement on late gadolinium-enhanced MR images.

Hemangiomas encasing the cavernous segment of the ICA usually do not cause luminal narrowing of the ICA, in contrast to meningiomas.

Pituitary Adenoma (Fig 8 and 9)

Pituitary adenomas are the most common lesion to secondarily involve the cavernous sinus. Pituitary macroadenomas are by definition >10 mm diameter masses arising from the pituitary gland, and usually extending superiorly into the suprasellar cistern where it can compress the chiasm.

Invasion of the cavernous sinus is an important prognostic factor with regard to surgery for pituitary adenomas, with a higher incidence of both intraoperative ICA injury and postoperative leakage of CSF when cavernous sinus invasion is present.

Diagnostic clue: Bilateral indentation by the diaphragma sellae as the tumor passes superiorly can give a snowman or figure-eight configuration. 

Craniopharyngiomas (Fig. 10)

Craniopharyngiomas arise from remnants of the craniopharyngeal duct. Cavernous sinus invasion is rare. Adamantinomatous craniopharyngiomas have a T1-hyperintense component owing to “motor oil cysts” (“machine oil cysts”) and are frequently calcified; papillary craniopharyngiomas are solid and are not calcified

Diagnostic clue: Pituitary gland seen separately from the mass.

Chondrosarcoma (Fig. 12)

Cranial chondrosarcomas usually arise from the skull base, most commonly at the site of the petro-occipital synchondrosis and can extend to involve the cavernous sinus.

Diagnostic clue: Off-midline location, very high T2 signal intensity because of the chondroid matrix. Regions of low signal intensity owing to calcifications. CT demonstrates matrix calcification in a chondroid pattern (“ring and arc” pattern) and helps in the assessment of bone destruction.

Chordoma

Chordomas are locally aggressive neoplasms of the axial skeleton, with around one-third occurring in the clivus, arising from the spheno-occipital junction.

Diagnostic clue: midline location, bone destruction.

Differentiation of chordomas from chondrosarcomas can be difficult at imaging, especially if the lesion grows in a position off the midline.

Juvenile Nasopharyngeal Angiofibroma (Fig. 13)

These lesions are histologically benign but locally aggressive neoplasms that arise in the nasal cavity or nasopharynx near the sphenopalatine foramen. They occur almost exclusively in adolescent male patients. Cavernous sinus invasion can occur owing to skull base erosion or extension by way of the skull base foramina. These tumors have a notorious tendency to bleed profusely when dissected. Hence, preoperative endovascular embolization of the tumor is a part of routine management of these lesions

Diagnostic clue: Flow voids and intense enhancement reflecting its highly vascular nature. Expansion of the pterygopalatine fossa and anterior bowing of the posterior wall of the maxillary sinus

Nasopharyngeal Carcinoma (Fig. 14)

Nasopharyngeal carcinomas are the most common primary malignancy of the nasopharynx and the most common extracranial malignancy to invade the cavernous sinus.

Diagnostic clue: Aggressive mass lesion. Bulky metastatic cervical lymphadenopathy.

Systemic neoplasia (Fig. 16)

Systemic lymphoma and leukemia can involve the cavernous sinus either by direct extension from adjacent structures, such as the marrow of surrounding bones or the nasopharynx, or by hematogenous dissemination. Most of these lesions represent non-Hodgkin lymphoma.

Diagnostic clue: T2 hypointensity and diffusion restriction.

Cavernous Sinus Thrombosis (Fig. 17)

Cavernous sinus thrombosis most often occurs as a complication of bacterial or fungal sepsis in the paranasal sinuses, the face, the orbits, and the skull base.

Imaging signs of cavernous sinus thrombosis include a bulky cavernous sinus, a convex configuration of the lateral wall, and filling defects within the sinus with absent enhancement. Indirect signs that support the diagnosis of cavernous sinus thrombosis are ipsilateral retro-orbital fat stranding, bulky extraocular muscles, and exophthalmos.

Diagnostic clue: Dilated SOV with loss of flow void.

ICA Aneurysm (Fig. 18)

Most cavernous ICA aneurysms are incidentally detected at imaging, most often in women older than 50 years.

At CT aneurysms are mildly hyperattenuating and can show peripheral curvilinear calcifications.

On T2 aneurysm can be seen as a flow void or can be heterogeneously hyperintense owing to slow flow or partial thrombosis. Completely thrombosed aneurysms generally demonstrate iso- to hyperintense signal intensity on both T1- and T2-weighted MR images. DSA plays an important role in planning management of cavernous ICA aneurysms.

Diagnostic clue: round shape of the lesion and its continuity with the ICA.

Carotid-Cavernous Fistula (Fig. 19)

CCF represents an abnormal communication from the carotid artery to the cavernous sinus; this communication can be either direct or indirect by way of the branches of the carotid artery. CCF can be traumatic or spontaneous

Features of CCF at routine imaging include a bulky ipsilateral cavernous sinus, a dilated superior ophthalmic vein, stranding of the retro-orbital fat, and bulky extraocular muscles.

Fungal Infection (Fig. 20)

Cavernous sinus involvement with fungal infection is due to spread from an invasive fungal infection of the paranasal sinus.

Commonly seen in immunocompromised patients. Angioinvasion by fungal hyphae is characteristic of this disease. Features of cavernous sinus thrombosis are seen.

CT demostrates hyperdensity and bone erosion, a specific feature suggestive of invasive disease.

The infarcted tissue characteristically has diffusion restriction and nonenhancing T2-hypointense nature; in the nasal turbinate, this feature has been called the “black turbinate sign”.