Orbital apex disorders: Imaging findings and management

Abstract

Orbital apex disorders include orbital apex syndrome, superior orbital fissure syndrome and cavernous sinus syndrome. These disorders result from various etiologies, including trauma, neoplastic, developmental, infectious, inflammatory as well as vascular causes. In the past, these have been described separately based on anatomical locations of disease process; however, these three disorders share similar causes, diagnostic evaluation and management strategies. The etiology is diverse and management is directed to the causative process. This imaging review summarizes the pertinent anatomy of the orbital apex and illustrates representative pathological processes that may affect this region. The purpose of this review is to provide an update on the current status of diagnostic imaging and management of patients with orbital apex disorders.

Introduction

Orbital apex (OA) disorders include three groups of disorders: orbital apex syndrome (OAS), superior orbital fissure syndrome (SOFS) and cavernous sinus syndrome (CSS). OAS, also known as Jacod syndrome, is an uncommon disorder related to various etiologies involving the OA, including trauma, neoplastic, developmental, infectious, inflammatory as well as vascular causes. It is characterized by ophthalmoplegia; proptosis; ptosis from palsy of cranial nerves (CN) III, IV, and VI; hypoesthesia of the ipsilateral forehead, upper eyelid and cornea by involvement of ophthalmic (V1) division of the trigeminal nerve; and eventual visual deficit from optic neuropathy.¹ SOFS, also known as Rochon-Duvigneaud syndrome, occurs from a lesion immediately anterior to the OA. It presents similarly to OAS, without the accompanying optic nerve impairment.^2,3 CSS includes hypoesthesia of the cheek and lower eyelid in addition to the signs seen in OAS due to involvement of maxillary (V2) division of the trigeminal nerve.^4,5 Additionally, CSS may present with oculosympathetic paresis (Horner’s syndrome) due to involvement of the sympathetic chain adjacent to the cavernous segment of the internal carotid artery (ICA).¹ Past literature has described these three syndromes separately based on the anatomical locations; however, these disorders share similar causes, diagnostic evaluation and management strategies.^1,6 The purpose of this review is to provide an update on the current status of diagnostic imaging and management of patients with OA disorders.

Applied anatomy

The osseous OA is formed by the superior orbital fissure and the optic canal (Figures 1 and 2). The optic canal is located in the superomedial corner of the OA and its contents include the optic nerve and ophthalmic artery (Table 1). The SOF lies inferior and lateral to the optic canal with an optic strut separating it from the optic canal.^7,8 The SOF contains the superior ophthalmic vein (SOV), CN III, IV, VI and the V1 of the trigeminal nerve (Table 1). Posterior to SOF is the cavernous sinus (Figure 1). The medial portion of the SOF contains CN III and VI, and the nasociliary nerve, which are enclosed in the annulus of Zinn, the tendinous ring for four of the six extraocular muscles (Figure 3). Superior and medial to the SOF, the annulus of Zinn contains the optic nerve and ophthalmic artery in the optic foramen. These structures are at greater risk of compression or shear injury as a result of their confinement within the annulus of Zinn.³ The lateral portion of the SOF contains CN IV, the frontal nerve, the lacrimal nerve, and the SOV.⁸ CN IV is less frequently involved in SOFS and OAS secondary to its anatomical location outside the annulus of Zinn.^3,9 Cavernous sinuses are located posterior to SOF and lateral to the sella turcica. V1 and V2 divisions of CN V, CN III and IV pass through the lateral wall of the cavernous sinus (Table 1). The ICA and adjacent sympathetic fibers pass through the medial portion of the sinus. CN VI passes through sinus between the ICA and the lateral wall.^7,8,10

Figure 1.

Orbital apex anatomy: CT. Axial and coronal CT slices demonstrate the useful clinical anatomy of the orbital apex. Red arrow: SOF, yellow arrow: greater wing of sphenoid, blue arrow: optic strut, green arrow: anterior clinoid process, white arrow: optic canal. CT: computed tomography; SOF: superior orbital fissure.

Figure 2.

Orbital apex anatomy: MRI. Top images: Axial T2W MR images (top) through the orbits demonstrate the useful clinical anatomy of the orbital apex. Red arrow: ICA, with arrow: cavernous sinus, blue arrow: SOF, green arrow: optic canal, white arrow: greater wing of sphenoid, pink arrow: optic nerve. Bottom image: Enlarged coronal T2W MR image though the orbital apex well demonstrates the anatomy. Yellow arrow: optic canal, red arrow: anterior clinoid process, blue arrow: SOF, white arrow: ethmoid sinus. MRI: magnetic resonance imaging; T2W: T2-weighted; ICA: internal carotid artery; SOF: superior orbital fissure.

Table 1.

Applied anatomy of orbit.

Structure	Contents
Superior orbital fissure	CN III, CN IV, CN V1, CN VI, superior ophthalmic vein
Inferior orbital fissure	CN II
Optic canal	CN II, ophthalmic artery
Cavernous sinus	CN III, CN IV, CN V1, CN V2, CN VIa, cavernous portion of ICAa

^aTrue contents. CN: cranial nerve; ICA: interior carotid artery.

Figure 3.

Diagrammatic representation of the right superior orbital fissure with its content. (Image modified from Rai S and Rattan V. Natl J Maxillofac Surg 2012; 3: 222–225, copyright 2012, Wolters Kluwer).⁴⁹

OA disorders

Definition

Until now the literature has described OAS, SOFS, and CSS separately based on the anatomical locations of the pathologic process; however, they share clinical features because of overlapping anatomical positions. Moreover, these syndromes can be progressive in nature, with SOFS developing into OAS or CSS.¹ Ophthalmoplegia results from impairment of CN III, IV, and VI.³ Ptosis results from impaired cranial nerve III innervation to the levator palpebrae superioris muscle or by loss of sympathetic innervation to the superior tarsal muscle.¹¹ Proptosis is caused by the loss of extraocular muscle tension on the globe, retrobulbar swelling, or venous congestion.² Impaired parasympathetic innervation from cranial nerve III results in mydriasis, and involvement of the nasociliary nerve results in loss of corneal reflex.² Injury to the optic nerve occurs most commonly at the intracanalicular portion of the optic nerve, especially in traumatic damage.¹² This is likely due to close approximation of the dural covering of the optic nerve with the periosteum of the optic canal, causing the optic nerve to be more susceptible to compression, tension, or shear injury.³ As V1 and V2 divisions of CN V passes through the lateral wall of the cavernous sinus, they both can be involved in CSS.⁵ However, CN VI is more frequently involved in CSS because of its location within the sinus when compared to CNs in the lateral wall.⁴ Communication via the intercavernous sinuses can result in bilateral cavernous sinus involvement.

Classification based on etiology

These disorders are classified based on etiology into trauma/iatrogenic, infectious, inflammatory process, neoplasms, vascular disorders and developmental (Table 2). Summarized clinical features and imaging findings are described in Table 3.

Table 2.

Etiologies of orbital apex disorder.

Etiology	Lesions
Traumatic	Cranio-maxillo-facial fractures
Iatrogenic	Sinonasal surgery Orbital/facial surgery Retained foreign body
Neoplastic	Metastases – Head and neck squamous cell cancers – Adenocystic carcinoma – Nasopharyngeal carcinoma Perineural spread of cancer Lymphoma/Leukemia Meningioma Nerve sheath tumors (schwannoma, neurofibroma)
Infectious	Fungus – Aspergillus – Mucormycosis Bacteria – Streptococcus – Staphylococcus – Actinomyces – Gram-negative bacilli – Anaerobes – Mycobacterium tuberculosis Spirochetes – Treponema pallidum Viruses – Herpes zoster
Inflammatory	Sarcoidosis Pseudotumor (idiopathic orbital inflammation), including variants – Nonspecific orbital inflammation without etiology – Tolosa–Hunt syndrome (apical variant form) – Immunoglobulin (Ig)G4-related disease (IgG4-RD) variant form – Sclerosing variant with chronic progressive fibrosis
Endocrine	Thyroid ophthalmopathy
Vascular	Cavernous sinus thrombosis Carotid cavernous fistula Carotid cavernous aneurysm
Developmental and hereditary	Dermoid Epidermoid Fibrous dysplasia Neurofibromatosis
Miscellaneous	Mucocele

Table 3.

Salient clinical and imaging features of orbital apex disorders.

Diagnosis		Salient clinical feature	CT	MRI	Post-contrast imaging
Traumatic	Craniomaxillofacial fractures	History of facial trauma	– Imaging of choice – CTA: if vascular injury is suspected	MRI reserved for evaluation of nerve injury	Not needed
Neoplastic	Metastases	Known or occult primary	Soft-tissue mass at orbital apex. MRI better than CT	T1WI best for evaluating marrow replacement	Local invasion, cavernous sinus, or intracranial extension
	PNTS	Known head and neck malignancy, most commonly: SCC	MRI is preferred	T1WI: enlarged/thickened nerves within canals and foramina – High T1 signal in adjacent muscles: denervation: leading to fatty replacement T2WI: replacement of normal high signal CSF in Meckel cave (CN5) by hypointense tumor	Abnormal enhancement of affected nerve
	Lymphoma	Systemic lymphoma or MALT lymphoma	Hyperdense or isodense masses	T1WI: iso- to hypointense T2WI: iso- to hypointense DWI: diffusion restriction	–Diffuse enhancement –Necrosis in post-treatment cases
	Meningioma	Often asymptomatic	– 75%: hyperdense – 25%: partially calcified “Tram-Track” calcification. Hyperostosis of underlying bone	T1WI: iso- to hypointense T2WI: iso- to hypointense	Homogenous enhancement
	Schwannoma	Most commonly arising from trigeminal nerve branches	Smooth bony erosion of central skull base with associated foraminal widening	T1WI- iso-to hypointense T2WI-hyperintense – Cyst formation is common – Well-defined cone shape if orbital apex is involved – Dumbbell shaped if SOF is involved	CEMR is best imaging tool
Infections	Orbital cellulitis	History of adjacent sinusitis	Ill-defined heterogeneous enhancing infiltrative soft tissue with extraconal and/or intraconal fat stranding	T1WI: hypointense T2WI: Heterogeneous hyperintense – Fungal infections: hypointense on T2WI	Diffuse heterogeneous enhancement
	Subperiosteal abscess	History of adjacent sinusitis	Lenticular rim-enhancing collection in extraconal orbit with displacement of extraocular muscles are evident on both CT and MR
Inflammatory	Sarcoidosis	Known sarcoidosis: chest symptoms	MRI is preferred. T1WI: hypointense. T2WI: variable hyperintense. CEMR is modality of choice. Diffuse enlargement and homogenous enhancement of optic nerve sheath with extension along intracranial optic nerve pathways
	IOI	Often unilateral. Bilateral involvement: 25%, often children. MRI is preferred. Orbital fat stranding, myositis, a focal intraorbital mass, lacrimal gland inflammation and enlargement, diffuse orbital involvement, and involvement of the optic nerve sheath complex, uvea and sclera.
	THS	Variant of IOI	Disease extends through orbital fissure into cavernous sinus
	Thyroid ophthalmopathy	Five years after onset of Graves’ disease. Exophthalmos, eyelid retraction, lagophthalmos	MRI is preferred. Order of EOM involvement: inferior> medial> superior> lateral rectus> oblique muscle bellies. – Mid-EOM belly thickness of > 5 mm, lacrimal gland enlargement, increased orbital fat, eyelid edema, stretching of the optic nerve, and tenting of the posterior globe T1WI: acute phase: isointense enlargement of EOM bellies and increased EOM signal on fat suppressed T1WI; T2WI: chronic phase: decreased T2 signal in EOM bellies; post-contrast: decreased EOM enhancement compared to normal, enlargement of SOV. Characteristic sparing of the tendinous insertion
Vascular	CCA	Orbital pain and diplopia	CT without contrast: well-defined round, slightly hyperattenuating lesions. Calcification ±	Non-thrombosed aneurysms: Flow void on T1 and T2WI. Thrombosed aneurysms– heterogeneous signal depending on the age of clot 3D-DSA is more sensitive than 2D-DSA for detecting small aneurysms	– Non-thrombosed aneurysms– bright with uniform enhancement, – Thrombosed aneurysm shows rim enhancement due to central filling defect
	CCF	Traumatic CCFs (direct): penetrating trauma or laceration secondary to skull base fracture. Acute onset pulsatile exophthalmos, chemosis, and bruit Nontraumatic CCFs (indirect): generally occurs days to months after onset	– Proptosis, enlarged SOV, CS and EOMs, dirty orbital fat due to edema. – Traumatic CCF is easy to recognize due to history of trauma and associated skull fracture.	T1WI: variable T2WI: asymmetric signal in CS due to increased flow voids – CTA and MRA show early enhancement of CS and SOV compared to other dural sinuses.	– Dilated SOV, asymmetric enhancement of CS and tortuous collaterals with cerebral drainage. – DSA is necessary for planning and treatment
	CST	Aseptic or septic. Staphylococcus is the most common pathogen in septic cases.	Asymmetrical and heterogeneous cavernous sinus, convex lateral margin, enlargement of SOV, associated sinusitis or orbital cellulitis in case of septic CST, with or without narrowing of cavernous portion of ICA or rarely pseudoaneurysm
Congenital/ Hereditary	PNF	Cosmetic facial deformities	Serpentine, non-capsulated infiltrative soft-tissue masses, skull base foramina widening optic canal and/or SOF	T1WI: heterogeneous T2WI: typical “target sign” due to hyperintense nodular mass with central low-signal	Heterogeneous enhancement – Frequently trans-spatial
	ONG	Visual impairment	MRI is preferred. Fusiform optic nerve masses, isointense on T1WI and hyperintense on T2WI with or without cystic components. Variable enhancement on post-contrast T1WI.
	FD	Congenital, often asymptomatic	CT is preferred. Expansile marrow lesion with variable attenuation. Sclerotic FD: ground-glass matrix, pagetoid FD-mixed lucent and sclerotic areas, cystic FD: central lucency with thin sclerotic borders. Narrowing of adjacent neural foramina, venous and arterial canals.		Post-contrast MR: variable enhancement
	Dermoid	Congenital, presents in second to third decade, with headaches (32%) and/or seizures (30%)	– Round/lobulated, well-delineated, unilocular cystic mass with fat density – Fluid or soft-tissue attenuation with or without capsular calcification	T1WI/ T2WI: hyperintense – Ruptured fat droplets may cause fat-fluid level within ventricles and may show adjacent inflammatory changes	Usually do not enhance
	Epidermoid	– Rare benign tumors – Clinically: gradual mass effect, headache, cranial nerve deficits, seizures, raised intracranial pressure	– Well-circumscribed cystic mass without complex features. – May cause scalloping of adjacent bone	– T1WI/T2WI: well-circumscribed mass with homogeneous fluid signal – DWI: restricted diffusion	Subtle rim enhancement can be seen
Miscellaneous	Mucocele	Frontal (60–65%), ethmoid (25%), maxillary (5–10%), sphenoid (2–5%)	– Low- or soft-tissue density opacification of sinus with expansion and remodeling of sinus wall. – High-density areas may be due to inspissated secretions or fungal colonization	MR features depend on the proportions of water, mucus and protein. – Water-rich contents show low signal on T1WI and high signal on T2WI. – Protein-rich contents show high signal on T1WI and low signal on T2WI DWI: variable diffusion restriction	– Thin peripheral enhancement – Thick peripheral enhancement usually due to superinfection (mucopyocele)

CEMR: contrast-enhanced magnetic resonance; CSF: cerebrospinal fluid; MRA: magnetic resonance angiography; MRI: magnetic resonance imaging; CT: computed tomography; CTA: computed tomography angiography; T1WI: T1-weighted imaging; T2WI: T2-weighted imaging; DWI: diffusion-weighted imaging; PNTS: perineural tumor spread; SCC: squamous cell cancer; IOI: idiopathic orbital inflammation; THS-Tolosa Hunt syndrome; EOM: extra-ocular muscles; CCA: carotid cavernous aneurysm; CCF: carotid-cavernous fistula; CST: cavernous sinus thrombosis; NF: neurofibroma; ONG: optic nerve glioma; FD: fibrous dysplasia; SOF: superior orbital fissure; ICA: internal carotid artery; DSA: digital subtraction angiography; 2D: two-dimensional; 3D: three-dimensional; MALT: mucosa-associated lymphoid tissue; SOV: superior ophthalmic vein.

Trauma/iatrogenic

OA disorders can occur as a result of either craniomaxillofacial trauma or iatrogenically during sinonasal/orbital/facial surgery. Limited data are available regarding the incidence of traumatic OAS or CSS; however, retrospective studies revealed the incidence of SOFS after facial trauma ranges from 0.3% to 0.8%.⁹ Both penetrating and blunt trauma can result in direct or indirect injury.¹² Direct injury either results from penetrating trauma or impingement of the OA by displaced bony fragments. Indirect injury results from high-energy impact to the face, thereby transmitting shear forces to the SOF or optic canal.¹³ The orbit is functionally a closed compartment, and rapidly increasing intraorbital pressure due to trauma can potentially result in permanent vision loss from ischemic damage to the retina and optic nerve.¹⁴ Associated retro-bulbar hemorrhage, edema and orbital emphysema is often present.

Imaging findings

The most common imaging findings in traumatic OA disorders are several comminuted fractures frequently involving the skull base, orbit, high transfacial (Le Fort), zygomatic maxillary complex or naso-orbito-ethmoidal regions.^9,15 Thin-section axial bone computed tomography (CT) with multiplanar reconstruction is the modality of choice (Figure 4). Three-dimensional (3D) CT reformatted images help in surgical planning, intraoperative navigation and execution of complex craniofacial fracture reconstruction. CT angiography is considered if vascular injury is suspected. MR is helpful for assessing associated intracranial and orbital soft-tissue injury.¹⁵

Figure 4.

Facial fractures. A 47-year-old male status post-motor vehicle collision. Axial computed tomography (CT) images in bone (a) and brain (b) windows demonstrate a comminuted fracture of the greater wing of the left sphenoid bone (red and yellow arrow), left lateral orbital wall (blue arrow), and lamina papyracea (green arrowhead) causing deformity of the face and irregularity of the optic canal. A small subarachnoid hemorrhage is seen more superiorly (curved white arrow). (c) CT image demonstrates comminuted fractures of the inferior orbital wall (green and blue arrows) and left maxillary sinus (red and yellow arrows) with resultant cranial caudal narrowing of the optic canal (curved white arrow).

Management

Early treatment is warranted. Orbital compartment syndrome is an emergency condition and a combination of corticosteroids therapy and decompressive surgery should be administered.^3,13 A multispecialty surgical approach is often needed. If not treated promptly, optic nerve compression can result in optic nerve ischemia and subsequently vision loss.

Neoplastic

Neoplastic etiology is most commonly seen in older age-group patients. Most common neoplastic involvement of the OA is by head and neck squamous cell carcinoma (SCC), adenocystic carcinoma, mucoepidermoid carcinoma and nasopharyngeal carcinoma either via perineural spread, local invasion, or metastasis.^16–19 Perineural tumor spread (PNTS) is most commonly seen with SCC, adenoid cystic carcinoma, as well as lymphomas and melanoma. Trigeminal nerve (CN V) is the most commonly affected at the skull base with involvement of maxillary (V2), mandibular (V3), and ophthalmic (V1) divisions in that order.^18,19 Perineural invasion of a cutaneous malignancy such as basal cell and SCCs have also been described.¹⁷ Primary neural tumors affecting the OA are less common.^1,18,19 In children, rhabdomyosarcoma is the most common orbital tumor causing OAS.²⁰ Lymphomatous involvement of the OA occurs with systemic lymphoma through localized invasion of the paranasal sinuses or skull base, or due to metastasis. The majority of orbital lymphomas are of B-cell origin.²¹ Non-Hodgkin lymphoma, specifically the mucosa-associated lymphoid tissue (MALT) subtype, is the most common primary orbital lymphoma.¹⁸ Infrequently, metastatic melanoma, metastases from breast, kidney, or lung cancers can result in an OA disorder.^1,18,19 Schwannomas are rare in the orbit, most commonly arising from trigeminal nerve branches and occasionally arising from peripheral branches of the CN III, CN IV, and CN VI, ciliary ganglia, as well as sympathetic and parasympathetic fibers.^1,18,19 Thin-section contrast-enhanced MR (CEMR) is the imaging modality of choice. Noncontrast CT better depicts any bony erosion/destruction and foramina widening.

Metastasis: imaging findings

CEMR can show local invasion of orbital soft tissue or cavernous sinus involvement as well intracranial extension better than CT. MR is more sensitive for depicting marrow replacement (Figure 5). Differential diagnoses include non-neoplastic infiltrative processes such as thyroid ophthalmopathy, idiopathic orbital inflammation (IOI) and granulomatous diseases, especially sarcoidosis, which are discussed later.

Figure 5.

Metastases: parotid adenoid cystic carcinoma. A 63-year-old female with parotid adenoid cystic carcinoma presenting with diplopia and visual field deficit. Axial (a) and coronal (b) post-contrast images demonstrate an enhancing lesion centered at the orbital apex (yellow arrow). Coronal images show extension of the lesion into the cavernous sinus (red arrow). (c) Axial post-contrast image through the brain (a) demonstrates an enhancing dural metastatic lesion (white arrow). Sagittal T2 (b), T1 (c), and post-contrast (d) images of the spine demonstrate abnormally low T1 signal throughout all vertebral bodies corresponding to widespread enhancing metastatic lesions.

PNTS: imaging findings

MR is more sensitive than CT for PTNS. Imaging shows focal or diffuse enlargement and enhancement of the CN, often with skipped areas, widening of associated skull base foramen, and muscular denervation atrophy. T1-weighted images (T1WI) can depict enlarged/thickened nerve replacing perineural high-signal fat within canals and foramina; high T1 signal in adjacent muscles indicates chronically denervated muscles, due to fatty replacement (Figure 6). T2-weighted images (T2WI) can depict replacement of normal high-signal cerebrospinal fluid in Meckel cave (CN5) by hypointense tumor. Post-contrast T1WI with fat suppression better depicts abnormal enhancement of the affected nerve (Figure 7). Differentials include neurofibroma, schwannoma and sarcoidosis.

Figure 6.

Perineural tumoral spread. A 59-year-old female with history of left forehead squamous cell carcinoma. Coronal post-contrast images through the orbits (a) and sphenoid sinus (b) demonstrate a thickened and enhancing right supraorbital nerve (red arrow) abutting the superior rectus with posterior extension to the orbital apex and superior orbital fissure (red and blue arrows). Axial post-contrast (c) is confirmatory.

Figure 7.

Perineural tumoral spread. Same patient as Figure 6, axial (a) and coronal (b) images through the level of pituitary in 2011 demonstrate normal left cavernous sinus and Meckel’s cave. In 2012, axial (c) and coronal (d) post-contrast images through the same region demonstrate enhancing tumor infiltrating the left cavernous sinus (yellow arrows) and left Meckel’s cave (red arrows).

Lymphoma: imaging findings

Lymphoma involves the orbital structures, such as the optic nerve and orbital wall, and may result in remodeling of adjacent bony wall. On CT, they are typically hyperdense or isodense. Lymphoma is iso- to hypointense on T1WI and T2WI, and shows diffusion restriction, with homogeneous enhancement. Necrosis occurs in post-treatment cases (Figure 8). Differentials include metastasis, sarcoid, PTNS, infection and meningioma.

Figure 8.

An 84-year-old female with transformed diffuse B-cell lymphoma refractory to therapy presenting with left vision loss and syncope. Axial T2 (a) and axial post-contrast (b) images through the brain demonstrate a dural-based enhancing lesion that extends into the orbital apex and optic nerve (red arrows). (c) Axial fluid-attenuated inversion recovery image through the basifrontal lobes (a) demonstrates associated white matter changes (red arrow). An axial post-contrast image (d) through the sphenoid air cells shows a peripherally enhancing fluid collection (red arrow). Biopsy of the sphenoid sinus revealed diffuse large B-cell lymphoma.

Meningioma: imaging findings

Meningioma tends to grow along the floor of the middle cranial fossa, anteriorly toward the OA, medially into the sella turcica, posterior into the Meckel’s cave, and inferiorly along the V3 into the foramen ovale and masticator space. Dural tail may or may not be apparent. On CT, at least 75% appears hyperdense and 25% at least partially calcified (Figure 9), may cause hyperostosis of underlying bone, and shows homogeneous enhancement. On MRI, these are hypo- to isointense to gray matter on T1WI and T2WI and show homogenous enhancement (Figure 10). Differentials include metastasis, sarcoidosis, neurofibroma, schwannoma and lymphoma. Primary optic nerve sheath meningiomas are less frequent than secondary lesions that extend from the intracranial site.¹⁸ They arise from the dura and displace the optic nerve or appear as tubular thickening around the nerve, sparing the substance of the nerve. A “tram-track” enhancement or calcification is often observed on imaging (Figure 9). A differential includes optic nerve glioma, which shows a thickened optic nerve.

Figure 9.

Meningioma: computed tomography. A 54-year-old female with right-sided diminution of vision. (a) axial, (b) coronal and (c) sagittal images through the right orbit show an enlarged left optic nerve with tram-track calcification around the right optic nerve (black arrows in (a) and (b), white arrow in (c)). This calcification is characteristic for optic nerve sheath meningioma.

Figure 10.

Meningioma: magnetic resonance imaging. A 61-year-old male with history of prior subtotal sphenoidal meningioma resection presenting with left eye blindness. Axial post-contrast images at the level of the superior orbital fissure (a) and cavernous sinus (b) demonstrate an extra-axial enhancing lesion (red arrows) related to the sphenoid bone extending into the superior orbital fissure (blue arrow), orbital apex, and cavernous sinus (curved yellow arrow). Coronal post-contrast image (c) through the orbits demonstrates the large enhancing mass (*) encircling and compressing the left optic nerve (red arrow). The normal right optic nerve is seen for comparison (yellow arrow in image (c)).

Schwannoma: imaging findings

Schwannomas are either well-defined cone shaped if the OA is involved or dumbbell shaped if SOF and show variable enhancement imaging. CT may show smooth bony erosion of the central skull base with associated foraminal widening. CEMR is the best imaging tool. Schwannomas are iso- to hypointense on T1WI and hyperintense on T2WI. Cyst formation is common (Figure 11). Differentials include meningioma, PTNS and lymphoma.

Figure 11.

A 56-year-old male with sudden-onset ophthalmoplegia and decreased facial sensation in the left V1 distribution. Axial T2 (a) and post-contrast (b) images demonstrate a cystic lesion in the left cavernous sinus (yellow arrow) with a fluid level (red arrow). No enhancement is seen (yellow arrow). Surgery revealed a hemorrhagic V1 schwannoma.

Management

Management of OA neoplasms is dictated by the causative pathology. Surgical resection, radiation therapy, and chemotherapy are all potential treatment modalities. If not treated promptly and accurately, disabling neurological symptoms including vision loss can occur.

Infection

Orbital infection is described with respect to the orbital septum, as either preseptal (periorbital) or post-septal (orbital). The orbital septum provides a barrier against spread of periorbital infections into the orbit proper and thus OAS is rarely a complication of preseptal cellulitis.² Orbital cellulitis is a post-septal infectious process most commonly due to adjacent sinusitis, either directly spread through bony erosion or pre-existing dehiscence of the sinus walls or via a perivascular pathway. Other related complications of sinusitis include Pott puffy tumor, orbital abscess, subperiosteal abscess (SPA) and septic cavernous sinus thrombophlebitis (CST).^22,23

Orbital (post-septal) cellulitis: imaging findings

Ill-defined heterogeneous enhancing infiltrative soft tissue with extraconal and/or intraconal fat stranding. Rapidly increasing intraorbital pressure may result in optic nerve traction and impending vision loss. On MR, inflammatory processes appear hypointense on T1WI and heterogeneous hyperintense on T2WI (Figure 12). A hypointense inflammatory process on T2WI is characteristic of fungal infection (Figure 13). Post-contrast T1WI shows diffuse heterogeneous enhancement. Differentials include IOI, immunoglobulin (Ig)G4-related disease (IgG4-RD), orbital sarcoidosis, and orbital lymphoproliferative lesions.

Figure 12.

Coronal (a), axial (b) T2W MR image shows a hyperintense lesion medial to the medial rectus muscle (yellow arrow) extending to the medial orbital wall forming sub-periosteal abscess and extending laterally into the intraconal fat. Post-contrast coronal T1W image (c) shows the enhancement (yellow arrow). This was a case of orbital cellulitis. T2W: T2-weighted; MR: magnetic resonance; T1W: T1-weighted.

Figure 13.

An 87-year-old male presenting with right eye pain, vision loss, ophthalmoplegia, and ptosis of the right eyelid. Axial T1 (a) and coronal T2 (b) images through the cavernous sinus demonstrate intermediate signal soft tissue (yellow arrows) expanding into the right cavernous sinus. Note lack of normal flow voids on the right compatible with internal carotid artery (ICA) thrombosis. A normal ICA flow void is seen on the left (red arrows in (a) and (b)). Axial (c) and coronal (d) post-contrast T1 images through the cavernous sinus demonstrate enhancement of the expansile right cavernous sinus soft tissue (yellow arrows). Again, note lack of normal right ICA flow voids and normal left-sided ICA flow voids (red arrows). Surgery revealed invasive fungal hyphae compatible with aspergillus.

Orbital or SPA: imaging findings

In addition to the aforementioned imaging features, a lenticular rim-enhancing mass in the extraconal orbit with displacement of extraocular muscles are evident both on CT and MR. Associated ethmoid sinusitis is almost always evident.

Treatment

Orbital cellulitis, orbital abscesses, and SPA are treated aggressively with appropriate broad-spectrum intravenous antibiotics. Additionally, surgical intervention is indicated in the presence of an orbital or SPA. Delay in treatment of orbital infections can result in vision loss and cavernous sinus thrombosis (CST).

Inflammatory disorders

Several inflammatory diseases can lead to OA disorders including granulomatosis with polyangiitis (Wagner’s disease), Churg-Strauss syndrome, and sarcoidosis.^1,5,24 Orbital sarcoidosis is a noncaseating granulomatous inflammation of the orbit without systemic manifestation. Orbital sarcoidosis may manifest most commonly as diffuse lacrimal gland infiltration, optic nerve sheath thickening and enhancement extending along optic nerve pathways, asymmetric extraocular muscle infiltration, intraorbital-enhancing soft tissue masses similar to pseudotumor, eyelid and periorbital preseptal infiltration, uveitis, and nasolacrimal apparatus. Other frequent causes include IOI and thyroid ophthalmopathy. IOI, previously known as orbital pseudotumor, is a non-granulomatous orbital inflammatory process. IOI is a diagnosis of exclusion with no known local or systemic cause.³ Three disease variants of IOI have been described: apical variant form Tolosa-Hunt syndrome (THS), IgG4-RD with plasma cell-mediated inflammation and a sclerosing form with chronic progressive fibrosis.²⁵ OA disorders are frequently caused by nonspecific IOI and a THS variant due to involvement of the cavernous sinus or OA. Cranial nerve paresis in THS typically coincides with the onset of pain or follows it within a period of as long as two weeks, although the pain or paresis usually resolves within 72 hours of corticosteroid therapy.²⁶ Thyroid ophthalmopathy often occurs five years after the onset of Graves’ disease.^27,28 Graves’ ophthalmopathy typically consists of an active inflammatory phase and an inactive fibrotic phase.^27–29 Symptoms are a result of autoimmune-mediated extraocular muscle enlargement and adipogenesis, which increases intraorbital pressure and impedes venous drainage.¹⁹ Physical examination shows exophthalmos, eyelid retraction with lagophthalmos, chemosis, and conjunctival injection. Restrictive ophthalmoplegia and visual impairment can occur in advanced cases.²⁷

Orbital sarcoidosis

OA disorders are generally caused by sarcoid involvement of the optic nerve sheath with extension along intracranial optic nerve pathways. CEMR is the modality of choice. It is hypointense on T1WI and variably hyperintense on T2WI, with significant enhancement (Figure 14). Contrast-enhanced computed tomography (CECT) and post-contrast T1WI can demonstrate diffuse enlargement and homogenous enhancement of the involved structure. Ga-67 scintigraphy is supportive but not specific. Differentials include IOI, lymphoproliferative disorders, and thyroid ophthalmopathy.

Figure 14.

A 64-year-old male presenting with right-sided vision loss and cranial neuropathy. The patient has a history of sarcoidosis. Axial (a) and coronal (b) post-contrast T1 images at the level of the cavernous sinus demonstrate enhancing extra-axial soft tissue along the greater wing of the right sphenoid (red arrow) with intracranial extension into the cavernous sinus (yellow arrows). Coronal computed tomography through the chest in soft tissue (c) and lung (d) window demonstrates anteroposterior window lymphadenopathy (yellow arrows) as well as upper lobe predominant fibrosis (red arrows) compatible with sarcoidosis.

Idiopathic orbital inflammation

Usually unilateral, bilateral in 25% cases. Bilateral cases are more common in children. Imaging features vary widely; however, they are similar to sarcoidosis: fat stranding, focal intra- or extraconal mass, myositis, enlarged and inflamed lacrimal gland, involvement of the orbit diffusely as well as uvea, sclera and optic nerve sheath complex (Figure 15).

Figure 15.

Orbital pseudotumor. A 42-year-old male with left eye exophthalmos, lid swelling, and facial swelling. Axial (a) and coronal (b) noncontrast computed tomography images through the orbits demonstrate enlargement and infiltrative changes of the lacrimal gland (yellow arrows) as well as of the extra-ocular muscles (red arrows). Axial short inversion time inversion recovery (STIR) (c) and post-contrast (d) images through the orbits show enlargement and increased signal in the left lateral rectus muscle (red arrow). Additionally, there is nodular extension of disease into the superior orbital fissure and orbital apex (thick yellow arrow). Symptoms resolved after steroid therapy.

THS variant

The disease extends through the orbital fissure into the cavernous sinus (Figure 16). Differentials include sarcoidosis, lymphoproliferative disorders, and thyroid ophthalmopathy.

Figure 16.

Tolosa Hunt syndrome. A 44-year-old female with waxing and waning ophthalmoplegia of the left eye for two years. The patient is treated episodically with mycophenolate mofetil and steroids. Post-contrast axial (a) and coronal (b) post-contrast images through the brain demonstrate an enhancing lesion extending from the orbital apex to the cavernous sinus (red arrows). The patient underwent external beam radiation for persistent symptoms. Follow-up contrast-enhanced magnetic resonance imaging ((c) and (d)) demonstrates normal cavernous sinuses bilaterally (red arrows). The enhancing lesion previously seen in the left cavernous sinus is no longer present.

Thyroid ophthalmopathy

Inferior, medial, superior, lateral rectus, oblique muscle bellies are involved in that descending order.² A mid-belly thickness of >5 mm is considered abnormal. Findings are often bilateral and symmetric; however, they can be unilateral.² Additional findings include increase in orbital fat, enlargement of the lacrimal gland, and lid edema, stretched optic nerve, with possible posterior globe tenting. Chronic atrophy of extra-ocular muscles (EOMs), fibrosis, and deposition of intramuscular fat are crucial points for diagnosis. MR findings in acute disease include isointense enlargement of EOM bellies on T1WI and increased EOM signal on fat-suppressed T1WI (Figure 17). However, in chronic disease, there is decreased T2 signal in EOM bellies. Additionally, there is thinning of the optic nerve posteriorly due to compression at the apex. There is characteristic sparing of the tendinous insertion. Post-contrast T1WI demonstrates decreased EOM enhancement compared to normal; there may also be enlargement of the SOV. Differentials include IOI, orbital sarcoidosis, and lymphoproliferative disorders.

Figure 17.

A 68-year-old male with Graves’ disease presenting with proptosis and diplopia. Coronal short inversion time inversion recovery (a) and axial post-contrast images through the orbits demonstrate an enlarged inferior rectus muscle with tendinous sparing (yellow arrows), which is characteristic of thyroid orbitopathy.

Management

Sarcoidosis and other granulomatous inflammatory disorders are managed via a multidisciplinary approach with systemic immunomodulatory agents, including corticosteroids, cyclophosphamide, methotrexate, and azathioprine.¹⁹ Steroid therapy classically results in rapid improvement in IOI including THS. The treatment of thyroid ophthalmopathy is dependent on the clinical phase of the disease, and consists of immunosuppression with corticosteroids in acute phases.²⁸ Decompressive surgery and radiation therapy are reserved for alleviating tension on the optic nerve.²⁹

Vascular disorders

Cavernous carotid aneurysms (CCA), carotid-cavernous fistulas (CCFs) and CST can result in an OA disorder. CCA can present with orbital pain and diplopia.^30,31 They may occur as a result of atherosclerosis, trauma, infection, or congenital weakening of the arterial wall.³⁰ Anterior growth of a CCA can result in compression of the optic nerve or superior orbital fissure, leading to an OAS or SOFS. Lateral growth compresses the cavernous sinus leading to CSS.³¹ Gradual progressive enlargement of the CCA leads to rupture and results in intracranial hemorrhage, CCF formation, or thromboembolism causing distal cerebral infarction.³⁰

CCFs are classified as traumatic or nontraumatic. Traumatic CCFs are direct, high-flow lesions, arising from a single-hole tear/transaction of the cavernous ICA with arteriovenous shunt into the cavernous sinus.^10,32 Injury to the carotid artery can be the result of penetrating trauma or laceration secondary to skull base fracture involving the sphenoid bone/carotid canal. CCFs give rise to venous hypertension and congestion, resulting in the characteristic triad of acute-onset pulsatile exophthalmos, chemosis, and bruit.³³ Venous hypertension can lead to intracranial hemorrhage, massive epistaxis, and cerebral or retinal ischemia.^10,32 Nontraumatic CCFs are mostly indirect, low-flow lesions arising from a cavernous sinus dural arteriovenous fistula (CSdAVF), which is a fistulous communication between the cavernous sinus or its tributaries with branches of the ICA or external carotid arteries or both.^10,34 Predisposing factors include postmenopausal female, Ehlers-Danlos syndrome, fibromuscular dysplasia, osteogenesis imperfecta and Pseudoxanthoma elasticum. Clinical symptoms generally occur days to months after onset. Rarely, nontraumatic AVF can be direct and high flow, resulting from spontaneous rupture of a CCA into the cavernous sinus.³⁴ Clinical symptoms occur early and are often severe, and may lead to rapid vision loss or subarachnoid hemorrhage.

CST/thrombophlebitis (CST) can be aseptic or septic. Aseptic CST occurs in patients predisposed to a hypercoagulable state such as malignancy, hereditary and acquired coagulopathies, pregnancy, oral contraceptives, post-surgical status and inflammatory bowel disease.³⁵ Septic CST commonly results from complication of infection, such as sinusitis, orbital cellulitis, odontogenic and otomastoiditis. Staphylococcus is the most common pathogen found.

CCAs: imaging findings

CT without contrast shows well-defined round, slightly hyperattenuating lesions. Calcification can be present. On CECT, non-thrombosed aneurysms appear bright with uniform enhancement; a thrombosed aneurysm shows rim enhancement due to central filling defect. On T1W and T2W MR, non-thrombosed aneurysms show flow void. Thrombosed aneurysms show heterogeneous signal intensity depending on the age of the clot. Three-dimensional digital subtraction angiography (DSA) is more sensitive than 2D-DSA for detecting small aneurysms.

CCFs: imaging findings

Non-contrast CT shows proptosis, enlarged SOV, CS and EOMs, and dirty orbital fat due to edema. T2WI shows an asymmetric signal in CS due to increased flow voids. On CECT and post-contrast T1WI, findings include dilated SOV, asymmetric enhancement of CS and tortuous collaterals with cerebral drainage (Figure 18). CT and MR angiography show early enhancement of CS and SOV compared to other dural sinuses. Traumatic CCF is easy to recognize owing to history of trauma and associated skull fracture. DSA is necessary for planning and treatment (Figure 17).

Figure 18.

A 67-year-old female presenting with proptosis, conjunctival arteriolization and cranial nerve VI palsy. Coronal three-dimensional contrast-enhanced magnetic resonance (MR) angiogram (a) through the cavernous sinuses demonstrates abnormal early enhancement and enlargement of the left cavernous sinus (yellow arrows). Axial post-contrast T1 (b) image demonstrates an enlarged left superior ophthalmic vein (curved red arrow). Frontal (c) and sagittal (d) angiographic images again demonstrate an abnormal early blush in the cavernous sinus (yellow arrows) as well as an enlarged draining superior ophthalmic vein (red arrows) compatible with a carotid cavernous fistula.

CST: imaging findings

Post-contrast imaging shows an asymmetrical and heterogeneous cavernous sinus, convex lateral margin, enlargement of SOV, associated sinusitis or orbital cellulitis in case of septic CST, with or without narrowing of the cavernous portion of the ICA or rarely pseudoaneurysm (Figure 19).

Figure 19.

A 48-year-old female presenting with question of left facial cellulitis. Axial post-contrast CT image through the cavernous sinus (a) demonstrates lack of normal cavernous sinus enhancement bilaterally (thin yellow arrows) compatible with cavernous sinus thrombosis. The internal carotid arteries (ICAs) show appropriate enhancement (thick blue arrows). More superiorly (b) an enlarged left superior ophthalmic vein is seen (curved red arrow). Note congestive changes in the overlying scalp and face (*). Axial post-contrast T1 (c) image through the cavernous sinuses again demonstrate lack of normal cavernous sinus enhancement (thin blue arrows) and normal ICA flow voids (thick yellow arrows). More superiorly (d), a distended right superior ophthalmic vein is seen (curved red arrow) secondary to back pressure.

Management

The treatment of choice for traumatic, direct CCF is endovascular embolization.^10,32,33,36 Surgical intervention may be considered if endovascular embolization fails.^10,37 Nontraumatic, indirect CCF can often be managed conservatively with regular follow-up to evaluate for changes in visual acuity, fundoscopic examination, or a significant increase in intraocular pressure.³⁸ Patients not responsive to medical therapy may require endovascular embolization or surgical intervention.^10,38

Management of septic and aseptic CST includes early anticoagulation.³⁹ Septic CST should be treated with aggressive broad-spectrum intravenous antibiotic therapy. Surgery is indicated to control the primary source of infection.

Small asymptomatic CCA can be managed conservatively with regular monitoring.⁴⁰ Endovascular or surgical interventions are considered in patients with significant OA symptoms or with a large aneurysm at risk of rupture.⁴⁰

Developmental and hereditary disorders

Neurofibromatosis

Orbital involvement by neurofibromatosis type 1 (NF 1) and type 2 (NF 2) are uncommon despite 25% to 30% occurrence in the head and neck.^41,42 NF1 orbital abnormalities include plexiform neurofibromas (PNFs), optic nerve pathway glioma (ONG), multiple localized neurofibroma (NF), sphenoid wing dysplasia, buphthalmos and optic nerve sheath ectasia.^41,42 NF2 orbital abnormalities include meningioma and schwannoma.¹⁸ Among these, orbital neurofibromas are more common. PNF is more common in orbit than multiple localized neurofibromas. Two percent to 16% of PNFs may undergo sarcomatous degeneration to malignant peripheral nerve sheath tumor.^41,42

PNF: imaging findings

PNFs appear as serpentine, noncapsulated infiltrative soft-tissue masses, associated with skull base foramina widening, particularly of the optic canal and/or SOF. MR images typically show a “target sign” due to a hyperintense nodular mass with central low signal on T2WI, heterogeneous on T1WI and show heterogeneous enhancement. The lesions are frequently transspatial. A differential includes schwannoma.

ONG: imaging findings

Mass arises from any of the segments of the optic nerve (intracranial, intracanalicular or intraorbital). These are fusiform optic nerve masses, isointense on T1WI and hyperintense on T2WI with or without cystic components with variable enhancement on post-contrast T1WI (Figure 20).

Figure 20.

Optic nerve glioma. (a) Axial T2WI and (b) T1WI MR in a patient with NF1 shows diffuse enlargement of the optic nerves bilaterally (yellow ovals in (a) and red ovals in (b)). The lesions extend posteriorly to involve the optic chiasm and optic tracts. These show heterogeneous enhancement on post-contrast T1W fat-suppressed images (blue ovals in (c)). T2WI: T2-weighted imaging; T1WI: T1-weighted imaging; MR: magnetic resonance; NF1: neurofibromatosis type 1.

Management

PNF is not surgically curable owing to its progressive infiltrative nature; debulking may be required to prevent vision loss. Radiation therapy is not effective.

ONG is generally observed unless vision is threatened. Radiation therapy and surgery are reserved for bulky tumors.

Fibrous dysplasia (FD)

Congenital disorder with defect in osteoblastic differentiation and maturation, resulting in progressive replacement of normal cancellous bone by mixture of fibrous tissue and immature woven bone.¹⁸ Craniofacial FD involving the greater wing of sphenoid can cause OA disorder by narrowing the optic canal.²⁵

FD: imaging findings

CT demonstrates an expansile marrow lesion with variable attenuation (Figure 20). Sclerotic FD: ground-glass matrix, pagetoid FD: mixed lucent and sclerotic areas, cystic FD: central lucency with thin sclerotic borders.⁴³ Post-contrast MR images show variable enhancement (Figure 21). Expansion of bone causes narrowing of adjacent neural foramina, venous and arterial canals.

Figure 21.

A 71-year-old female with progressive right visual loss and proptosis. Axial computed tomography through the orbit (a) demonstrates an expansile ground-glass lesion (yellow arrow) in the right greater wing of the sphenoid. Note narrowing of the optic canal (red arrow) and proptosis (curved blue arrow). Axial (b) and coronal (c) post-contrast magnetic resonance images demonstrate mild enhancement (yellow arrow). Although having classic appearance for fibrous dysplasia, this case was confirmed with surgery.

Management

Decompressive surgery for alleviating tension on the involved nerve may be needed.

Dermoid and epidermoid cysts

Dermoid cysts are congenital, benign, slow-growing lesions representing closed sacs lined by ectoderm. They are divided into deep (intracranial/orbital) or superficial (adjacent to the orbital rim). OA disorders can be caused by complication of deep dermoid cysts. Clinically these present with headache (32%) and seizures (30%) in the second to third decade.⁴⁴ A large suprasellar cyst may present with OAS or CSS. Cyst rupture can cause chemical meningitis (6.9%).⁴⁴ There are two theories of etiology: (i) sequestration of surface ectoderm at lines of epithelial fusion/along course of normal embryonic invaginations; (ii) inclusion of cutaneous ectoderm at time of neural tube closure.

Epidermoid cysts are rare benign tumors secondary to dysembryogenesis. Clinically present due to gradual mass effect, headache, cranial nerve deficits, seizures, raised intracranial pressure.⁴⁵

Dermoid cyst: imaging findings

CT demonstrates a lobulated or round, well-circumscribed, cystic lesion with fat attenuation, fluid or soft-tissue attenuation with or without capsular calcification. On T1WI/T2WI this may appear hyperintense (Figure 22). Ruptured fat droplets may cause fat-fluid level within ventricles and may show adjacent inflammatory changes. Differentials include epidermoid cyst, lipoma, craniopharyngioma, and partially thrombosed aneurysm.

Figure 22.

Dermoid cyst. Axial T1WI (a), axial GRE (b), axial post-contrast T1WI (c), axial T2WI (d), coronal T2WI (e) MR images demonstrate a circumscribed T1 and T2 hyperintense, nonenhancing mass in the antero-lateral cavernous sinus (yellow arrows). (f) CT shows fat density in the posterior aspect of the mass (red circle). T1WI: T1-weighted imaging; GRE: gradient echo; T2WI: T2-weighted imaging; MR: magnetic resonance; CT: computed tomography.

Epidermoid cyst: imaging findings

A well-circumscribed cystic mass without complex features, an epidermoid cyst may cause scalloping of adjacent bone. On T1WI/T2WI it can appear as a well-circumscribed mass with homogeneous fluid signal and show restricted diffusion (Figure 23). On post-contrast imaging subtle rim enhancement can be seen. Differentials include arachnoid cyst, dermoid cyst, inflammatory cysts such as neurocysticercosis, and cystic tumors (schwannoma, craniopharyngioma).

Figure 23.

Epidermoid cyst. (a) Axial T2WI shows a high-signal intensity oval lesion (red arrow) in the anterior left cavernous sinus, and with no enhancement on post-contrast T1WI (yellow arrow in (b)). This lesion is hyperintense on DWI (blue circle in (c)) and shows restricted diffusion on ADC map (green circle in (d)), compatible with orbital apex epidermoid. T2WI: T2-weighted imaging; T1WI: T1-weighted imaging; DWI: diffusion-weighted imaging; ADC: apparent diffusion coefficient.

Management

Dermoid cysts are treated with complete surgical excision to prevent recurrence.

Epidermoids are treated with surgical excision if symptomatic. Recurrence can occur if complete excision is not possible.

Miscellaneous

Mucocele

Mucocele are opacified, expanded sinus with smooth remodeling of walls. Frontal (60–65%), ethmoid (25%), maxillary (5–10%), sphenoid (2–5%). Ethmoid mucoceles have the greatest potential for intraorbital extension. The OA can be compressed by a mucocele arising from the posterior ethmoid sinus or rarely from the sphenoid sinus.⁴⁶

Imaging findings

CT shows a low- or soft-tissue density opacification of the sinus with expansion and remodeling of the sinus wall, and high-density areas related to inspissated secretions or fungal colonization. MR features depend on the amount of protein, water and mucus. Water-rich contents show low signal on T1WI and high signal on T2WI, and protein-rich contents show high signal on T1WI and low signal on T2WI (Figure 24). CECT and CEMRI reveal thin peripheral enhancement. Thick peripheral enhancement raises suspicion of superinfection (mucopyocele). DWI can show variable restriction diffusion.^47,48

Figure 24.

Sphenoid mucocele. Axial (a) and coronal (b) CT images show an isodense expansile lesion (yellow ovals) in the sphenoid sinus causing narrowing of the right superior orbital fissure (red arrow). Axial (c) and sagittal (d) T1W MR images show the lesion to be T1 hyperintense (green oval). Note right superior orbital fissure (blue arrow). The lesion is isointense (pink ovals) on T2W images ((e) and (f)). CT: computed tomography; T1W: T1-weighted; MR: magnetic resonance; T2W: T2-weighted.

Management

The affected sinus should be drained and marsupialized. In some cases, reconstructive surgery may be needed. Recurrence occurs if drainage is impaired.

Conclusion

Knowledge of the imaging features of these disease entities will lead to a more accurate diagnosis that may result in a targeted comprehensive therapeutic approach for optimal patient care.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflict of interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.