Radiology Review Manual (Dahnert, Radiology Review Manual)

Authors: Dahnert, Wolfgang

Title: Radiology Review Manual, 6th Edition

Copyright 2007 Lippincott Williams & Wilkins

> Table of Contents > Orbit

Orbit

Differential Diagnosis of Orbital and Ocular Disorders

Ophthalmoplegia

• Lesions of

  • Oculomotor nerve (III)

    • innervates medial rectus, superior rectus, inferior rectus, inferior oblique muscle, pupilloconstrictor, levator palpebrae

  • Trochlear nerve (IV)

    • innervates superior oblique muscle

  • Abducens nerve (VI)

    • innervates lateral rectus muscle

Anopia

[numbers refer to drawing]

• MONOCULAR DEFECTS

  1	= monocular blindness (optic nerve lesion in fracture of optic canal, amaurosis fugax)

• BILATERAL heteronymous DEFECTS

  2	= bitemporal hemianopia (chiasmatic lesion)

• BILATERAL HOMONYMOUS DEFECTS

  3

  = homonymous hemianopia

  4

  = upper right-sided quadrantanopia

  3,4,5

  = most common type of hemianopia (CVA, brain tumor)

  Types of Anopia

Monocular Blindness In Adulthood

• Optic neuritis

• Vascular ischemia

  • Amaurosis fugax = cholesterol emboli from internal carotid artery occluding central retinal artery and its branches

  • Occult cerebrovascular malformation affecting the optic nerve

• Temporal arteritis

• Malignant optic glioma of adulthood

Orbit

Spectrum of Orbital Disorders

• INFLAMMATORY DISEASE

  • Tissue-specific inflammation:

    • orbital cellulitis, optic neuritis, scleritis, myositis, Graves disease

  • Panophthalmitis

  • Pseudotumor of orbit

• CYSTIC DISEASE

  • Dermoid cyst

  • Mucocele

  • Retro-ocular cyst (developmental)

P.338

• VASCULAR DISEASE

  • Cavernous angioma

  • Capillary angioma

  • Lymphangioma

  • Varix

  • Carotid-cavernous fistula

• TUMORS

  • Rhabdomyosarcoma

  • Optic nerve glioma

  • Meningioma

  • Lymphoma

  • Metastasis

Intraconal lesion

• Melanoma

• Metastasis

• Retinoblastoma

• Meningioma

• Hemangioma

• Optic glioma

• Pseudotumor

• Cellulitis

• Grave disease

Intraconal Lesion with Optic Nerve Involvement

• Optic nerve glioma

• Optic nerve sheath meningioma (10% of orbital neoplasm)

• Optic neuritis

• Inflammatory pseudotumor (may surround optic nerve)

• Sarcoidosis

• Intraorbital lymphoma (may surround optic nerve, older patient)

• Elevated intracranial pressure

  • = distension of optic sheath

  • bilateral tortuous enlarged optic nerve-sheath complex

Optic Nerve Tram-track Sign

• Optic nerve sheath meningioma

• Orbital pseudotumor

• Perioptic neuritis

• Perioptic hemorrhage

• Sarcoidosis

• Lymphoma / leukemia

• Metastasis

• Erdheim-Chester disease = systemic xanthogranulomatosis

Intraconal Lesion without Optic Nerve Involvement

• Cavernous hemangioma

• Orbital varix

• Carotid-cavernous fistula

• Arteriovenous malformation

  • least common of orbital vascular malformations (congenital, idiopathic, traumatic)

  • irregularly shaped intensely enhancing mass of enlarged vessels

  • associated with dilated superior / inferior ophthalmic vein

• Hematoma

• Lymphangioma

• Neurilemoma

  • commonly adjacent to superior orbital fissure, inferior to optic nerve

  • local bone erosion

Extraconal lesion

Extraconal-intraorbital Lesion

• BENIGN TUMOR

  • Dermoid cyst

  • Teratoma

    • <1% of all pediatric orbital tumors

    • areas of fat, cartilage, bone

    • expansion of bony orbit bone defect

  • Capillary hemangioma

  • Lymphangioma

  • Plexiform neurofibroma

  • Inflammatory orbital pseudotumor

  • Histiocytosis X

    • lesion usually arises from bone

• MALIGNANT TUMOR

  • Lymphoma / leukemia

  • Metastasis

  • Rhabdomyosarcoma

    mnemonic:

    MOLD

  • Metastasis

  • Others (rhabdomyosarcoma, lymphangioma, sinus lesion)

  • Lymphoma, Lacrimal gland tumor

  • Dermoid

Extraconal-extraorbital Lesion

• FROM SINUS

  • maxillary / sphenoid sinuses are rare locations of origin

  • Tumor:

    • squamous cell carcinoma (80%), lymphoma, adenocarcinoma, adenoid cystic carcinoma

  • Mucocele

  • Paranasal sinusitis:

    • Most common cause of orbital infection!

      Origin:	from ethmoid sinuses (in children), from frontal sinus (in adolescence)
      Organism:	Staphylococcus, Streptococcus, Pneumococcus

    • preseptal / orbital edema / cellulitis

    • subperiosteal / orbital abscess

    • mucormycosis (in diabetics) destroys bone + extends into cavernous sinus

    • Cx:

      • epidural abscess

      • subdural empyema

      • cavernous sinus thrombosis

      • meningitis

      • cerebritis

      • brain abscess

• FROM SKIN

  • Orbital cellulitis

• FROM LACRIMAL GLAND

  • mass arising from superolateral aspect of orbit

P.339

Orbital mass

Orbital Mass in Childhood

• Leukemia, Lymphoma

• Optic nerve glioma

• Vascular malformation: hemangioma, lymphangioma

• Inflammation

• Sarcoma: ie, rhabdomyosarcoma

• Histiocytosis

• Orbital pseudotumor, Osteoma

• Neuroblastoma

Primary Malignant Orbital Tumors

Secondary Malignant Orbital Tumors

Orbital Cystic Lesion

• Abscess

• Intraorbital hematoma

• Dermoid cyst

• Lacrimal cyst

• Lymphangioma

• Hydatid cyst

Orbital Vascular Tumors

• Orbital varix

• Arteriovenous malformation

• Carotid-cavernous fistula

• Hemangioma: capillary / cavernous

• Blood cyst

• Arterial malformation

• Glomus tumor

• Hemangiopericytoma

Mass in Superolateral Quadrant of Orbit

• Lacrimal gland tumor

• Dermoid cyst

• Metastasis (breast, prostate, lung)

• Lymphoma

• Leukemic infiltration of lacrimal gland

• Sarcoidosis

• Wegener granulomatosis

• Pseudotumor

• Frontal sinus mucocele

Extraocular Muscle Enlargement

• ENDOCRINE

  • Graves disease (50%)

  • Acromegaly

• INFLAMMATION

  • Myositis

    • rapid onset of proptosis, erythema of lids, conjunctival injection

      Location:

      single muscle (in adults); multiple muscles (in children)

    • enlarged extraocular muscle

    • positive response to steroids

  • Orbital cellulitis

  • Sj gren disease, Wegener granulomatosis, lethal midline granuloma, SLE

  • Sarcoidosis

  • Foreign-body reaction

• TUMOR

  • Pseudotumor

  • Rhabdomyosarcoma

  • Metastasis, lymphoma, leukemia

• VASCULAR

  • Spontaneous / traumatic hematoma

  • Arteriovenous malformation

  • Carotid-cavernous sinus fistula

Globe

Spectrum of Ocular Disorders

• CONGENITAL

  • Persistent hyperplastic primary vitreous

  • Coats disease

  • Coloboma

  • Congenital cataract

• VITREORETINAL

  • Vitreous hemorrhage

  • Retinal detachment

  • Choroidal detachment

  • Endophthalmitis

  • Retinoschisis

  • Retrolental fibroplasia

• TUMOR

  • Retinoblastoma

  • Choroidal hemangioma

  • Retinal angiomatosis

  • Melanocytoma

  • Choroidal osteoma

• TRAUMA

Microphthalmia

• = congenital underdevelopment / acquired diminution of globe

• BILATERAL with cataract

  • Congenital rubella

  P.340

  • Persistent hyperplastic vitreous

  • Retinopathy of prematurity

  • Retinal folds

  • Lowe syndrome

    • small globe + small orbit

• UNILATERAL

  • Trauma / surgery / radiation therapy

  • Inflammation with disorganization of eye (phthisis bulbi)

    • shrunken calcified globe + normal orbit

Macrophthalmia

• = enlargement of globe

• WITHOUT INTRAOCULAR MASS

  • generalized enlargement

    • Axial myopia (most common cause)

      • enlargement of globe in AP direction

      • thinning of sclera

    • Buphthalmos

    • Juvenile glaucoma

    • Connective tissue disorder:

      • Marfan syndrome, Ehlers-Danlos syndrome, Weill-Marchesani syndrome (congenital mesodermal dysmorphodystrophy), homocystinuria

      • wavy contour of sclera

  • focal enlargement

    • Staphyloma

    • Apparent enlargement due to contralateral microphthalmia

• WITH INTRAOCULAR MASS

  • (rare cause for enlargement)

  • with calcifications:

    • Retinoblastoma

  • without calcifications:

    • Melanoma

    • Metastasis

Ocular Lesion

Intraocular Calcifications

• Retinoblastoma (>50% of all cases)

• Astrocytic hamartoma

• Choroidal osteoma

• Optic drusen

• Scleral calcifications

  • in systemic hypercalcemic states (HPT, hypervitaminosis D, sarcoidosis, secondary to chronic renal disease)

  • in elderly: at insertion of extraocular muscles

• Retrolental fibroplasia

• Phthisis bulbi

  • secondary to trauma or infection

  • small contracted calcified disorganized nonfunctioning globe

    mnemonic:

    NMR CT

  • Neurofibromatosis

  • Melanoma (hyperdense melanin)

  • Retinoblastoma

  • Choroidal osteoma

  • Tuberous sclerosis

Noncalcified Ocular Process

• Uveal melanoma

• Metastasis

  • 86% of ocular lesions within globe; usually in vascular choroid

  • Origin: breast, lung, GI tract, GU tract, cutaneous melanoma, neuroblastoma

  • bilateral in 30%

• Choroidal hemangioma

• Vitreous lymphoma

  • diffuse ill-defined soft-tissue density

• Developmental anomalies

  • Primary glaucoma = enlargement of eye secondary to narrowing of Schlemm canal

  • Coloboma

  • Staphyloma

Vitreous Hemorrhage

• visual loss frequent

• US:

  • numerous irregular, poorly defined low-intensity echoes:

  • echogenic material moving freely within vitreous chamber during eye movement

  • voluminous hyperechoic fibrin clots not fixed to optic nerve (DDx to retinal detachment)

    Prognosis:	complete absorption / development of vitreous membranes (repetitive episodes)
    Cx:	retinal detachment (vitreous traction secondary to fibrovascular ingrowth following hemorrhage)

Dense Vitreous in Pediatric Age Group

• Retinoblastoma

• Persistent hyperplastic primary vitreous

• Coats disease

• Norrie disease

• Retrolental fibroplasia

• Sclerosing endophthalmitis

Leukokoria

• = abnormal white / pinkish / yellowish pupillary light reflex [leuko, Greek = white and koria, Greek = pupil]

• TUMOR

  • Retinoblastoma (most common cause 58%)

  • Retinal astrocytic hamartoma (3%):

    • associated with tuberous sclerosis + von Recklinghausen disease

  • Medulloepithelioma (rare)

• DEVELOPMENTAL

  • Persistent hyperplastic primary vitreous

    • (2nd most common cause 28%)

  • Coats disease (16%)

  • Retrolental fibroplasia (3 5%)

  • Coloboma of choroid / optic disc

• INFECTION

  • Uveitis

  • Larval granulomatosis (16%)

• DEGENERATIVE

  • Posterior cataract

P.341

• TRAUMA

  • Retinopathy of prematurity (5%)

  • Organized vitreous hemorrhage

  • Long-standing retinal detachment

Leukokoria in Normal-sized Eye

• CALCIFIED MASS

  • Retinoblastoma

  • Retinal astrocytoma

• NONCALCIFIED MASS

  • Toxocaral endophthalmitis

  • Coats disease

Leukokoria with Microphthalmia

• UNILATERAL

  • Persistent hyperplastic primary vitreous (PHPV)

• BILATERAL

  • Retinopathy of prematurity

  • Bilateral PHPV

Optic nerve

Optic Nerve Enlargement

• TUMOR:

  • Optic nerve glioma

  • Optic nerve sheath meningioma

  • Infiltration by leukemia / lymphoma

• FLUID:

  • Perineural hematoma

  • Papilledema of intracranial hypertension

  • Patulous subarachnoid space

• INFLAMMATION:

  • Optic neuritis

  • Sarcoidosis

• fusiform thickening

  • = lens-shaped thickening of nerve-sheath complex

  • with central lucency: meningioma

  • without central lucency: optic nerve glioma

• excrescentic thickening

  • = single / multiple nodules along nerve-sheath complex usually due to tumor

• tubular enlargement

  • = uniform enlargement of nerve-sheath complex

  • with central lucency: subarachnoid process (metastases, perineuritis, meningioma, perineural hemorrhage)

  • without central lucency: papilledema, leukemia, lymphoma, sarcoid, optic nerve glioma

Lacrimal gland

Lacrimal Gland Lesion

• INFLAMMATION

  • Dacryoadenitis

  • Mikulicz syndrome

    • = nonspecific enlargement of lacrimal + salivary glands

      Associated with:

      sarcoidosis, lymphoma, leukemia

  • Sj gren syndrome

    • = lymphocytic infiltration of lacrimal + salivary glands

    • decreased lacrimation, xerostomia

    • Often associated with:

      • rheumatoid arthritis, systemic lupus erythematosus, scleroderma, polymyositis

  • Sarcoidosis

• TUMOR

  (a) benign:	granuloma, cyst, benign mixed tumor (= pleomorphic adenoma)
  (b) malignant:	malignant mixed tumor (= pleomorphic adenocarcinoma), adenoid cystic carcinoma, lymphoma, metastasis (rare)

Lacrimal Gland Enlargement

• Metastasis

• Epithelial tumor

• Lymphoid tumor

• Dermoid

Bilateral Lacrimal Gland Masses

• Lymphoma

• And

• Collagen-vascular disease

• Sarcoidosis

P.342

Anatomy of Orbit

Orbital connections

Superior Orbital Fissure

Boundaries (Gray's Anatomy):

Contents:

• nerves:

  • III oculomotor n.

  • IV trochlear n.

  • V₁ ophthalmic branch of trigeminal n.:

    • lacrimal nerve

    • frontal nerve

  • VI abducens n.

  • sympathetic filaments of internal carotid plexus

• veins: superior + inferior ophthalmic vein

• arteries:

  • meningeal branch of lacrimal artery

  • orbital branch of middle meningeal artery

Inferior Orbital Fissure

Location: between floor + lateral wall of orbit; connects with pterygopalatine + infratemporal fossa

Contents:

• nerves: infraorbital + zygomatic nn. branches from pterygopalatine ganglion

• veins: connection between inferior orbital v. + pterygoid plexus

Optic Canal

completely formed by lesser wing of sphenoid

Contents:

• nerve: optic nerve (I)

• vessel: ophthalmic a.

Normal orbit measurements

Muscles

Superior ophthalmic vein

Optic nerve sheath

Globe position

Orbital compartments

the orbital septum + globe divide orbit into

• Anterior Compartment

  lids, lacrimal apparatus, anterior soft tissues

• Posterior Compartment

  • =Retrobulbar Space = the cone consisting of extraorbital muscles + envelope of fascia divides retrobulbar space into

  • intraconal space

  • extraconal space

  Coronal Orbital Tomogram through Midorbit

P.343

Orbital Spaces

P.344

Orbital and Ocular Disorders

Buphthalmos

• =hydrophthalmos = megophthalmos

• =diffuse enlargement of eye in children secondary to increased intraocular pressure

Cause:

• Congenital / infantile glaucoma

• Neurofibromatosis type 1: obstruction of canal of Schlemm by membranes / masses composed of aberrant mesodermal tissue

• Sturge-Weber-Dimitri syndrome

• Lowe (cerebrohepatorenal) syndrome

• Ocular mesodermal dysplasia (eg, Axenfeld or Rieger anomalies)

• Homocystinuria

• Aniridia

• Acquired glaucoma (rare)

Pathophysiology:

• obstruction of canal of Schlemm located between cornea + iris leads to decreased resorption of aqueous humor (= anterior chamber fluid) with scleral distension

• uniformly enlarged globe without mass of round / oval / bizarre shape

Rx: goniotomy (increases the angle of anterior chamber); trabeculotomy (lyses of adhesions)

Carotid-Cavernous Sinus Fistula

= abnormal communication between internal carotid artery + veins of cavernous sinus

Etiology:

• Trauma: laceration of ICA within cavernous sinus

  • usually secondary to basal skull fracture (cavernous ICA + small cavernous branches fixed to dura)

  • penetrating trauma

• Spontaneous: rupture of an intracavernous ICA aneurysm

Route of drainage:

• superior ophthalmic vein (common)

• contralateral cavernous sinus

• petrosal sinus

• cortical veins (rare)

• pulsating exophthalmos, chemosis, conjunctival edema

• persistent orbital bruit

• restricted extraocular movement

• decrease in vision due to increase in intraocular pressure (50%) = indication for emergent treatment

  • enlarged edematous extraocular muscles

  • dilatation of superior ophthalmic vein / facial veins / internal jugular vein

  • focal / diffuse enlargement of cavernous sinus

  • occasionally sellar erosion / enlargement

  • enlargement of superior orbital fissure (in chronic phase)

US + MR:

arterial flow in cavernous sinus + superior ophthalmic vein

Angio:

• ipsilateral ICA contrast injection shows wall of ICA to be incomplete

• contralateral ICA contrast injection + compression of involved ICA

• early opacification of veins of cavernous sinus

• retrograde flow through dilated superior ophthalmic v.

Rx: latex / silicone balloon detached inside cavernous sinus to plug laceration (ocular signs resolve within 7 10 days)

Choroidal Detachment

Cause: trauma, surgical intervention, spontaneous

US:

• two convex lines projecting into the eye from periphery of globe + advancing to ciliary body with posterior fixation outside the optic disk (= macula)

• minimal / no choroidal membrane mobility during eye movement

Choroidal Hemangioma

= vascular hamartoma

• 0.5 3-mm small tumor

• focal thickening of posterior wall of globe

• enhancement similar to choroid

• retinal detachment (frequent)

US:

• hyperechoic homogeneous mass

DDx: melanoma (choroidal excavitation)

Choroidal osteoma

= rare juxtapapillary tumor of mature bone

small flat very dense curvilinear mass aligned with choroidal margin of globe

Coats Disease

• = Retinal Telangiectasia = pseudoglioma

• = congenital idiopathic primary vascular malformation of the retina characterized by

  • multiple abnormal telangiectatic retinal vessels

  • lack of blood-retina barrier causing leakage of a lipoproteinaceous exudate into retina + subretinal space with secondary detachment of retina

Age: 6 8 years (but present at birth); M:F = 2:1

• strabismus

• may present with leukokoria (if retina massively detached) [16% of leukokoria cases]

• loss of vision, secondary glaucoma

• cholesterol crystals at funduscopy

NO focal mass / calcification (HALLMARK)

US:

• clumpy particulate echoes in subretinal space (due to cholesterol crystals suspended in fluid)

• vitreous + subretinal hemorrhage (frequent)

P.345

DDx: unilateral noncalcifying retinoblastoma (before 3 years of age, no microphthalmia)

CT:

• unilateral dense vitreous in normal-sized globe

MR:

• hyperintense subretinal exudate on T1WI + T2WI (due to mixture of protein + lipid) / hypointense on T2WI (cholesterol crystals + membranous lipids)

• abnormal enhancement of retina at ora serrata + of detached retinal leaves

Coloboma

[koloboun, Greek = to mutilate]

= incomplete closure of embryonic choroidal fissure affecting eyelid / lens / iris / choroid / retina / macula; autosomal dominant trait with variable penetrance (30%) and expression; bilateral in 60%

• cystic outpouching (= herniation) of vitreous at site of optic nerve attachment

• small globe

Congenital Cataract

= opacification of lens

US:

• increase in thickness + echogenicity of posterior wall of lens intralenticular echoes

Dacryoadenitis

= infection of lacrimal gland

• homogeneous enlargement of lacrimal gland

• compression of globe

Dermoid Cyst of Orbit

Most common benign orbital tumor in childhood (45% of all masses)

• well-defined cystic mass negative HU numbers

• thick surrounding capsule

• expansion / erosion of bony orbit

US:

encapsulated heterogeneous mass with variable cystic component

MR:

high signal intensity on T1WI + T2WI

Endophthalmitis

Infectious Endophthalmitis

• exogenous endophthalmitis: most commonly related to eye injury / surgery

• endogenous endophthalmitis: hematogenous spread from distant source of infection

US:

• medium- to high-intensity echoes dispersed throughout vitreous (DDx: echoes in vitreous hemorrhage are more mobile)

CT:

• increased attenuation of vitreous

• uveal-scleral thickening

• decreased attenuation of lens

Sclerosing Endophthalmitis

• = Toxocara Canis Endophthalmitis

• = granulomatous uveitis resulting in subretinal exudate, retinal detachment, organized vitreous

Life cycle:

egg hatches into larva within intestines of definite host (dog) + develops into adult worm; alternatively dog may eat infective-stage larvae from intestines / viscera of other animals; in noncanine host larvae will not develop into adult worm, but burrow through intestinal wall and migrate to liver, lung, and other tissue including brain + eye

Pathophysiology:

migration through human tissue produces a severe eosinophilic reaction that becomes granulomatous; spreads hematogenously to temporal choroid

• red hot eye, photophobia, pain

• anterior chamber flare cells, keratic precipitates

• vitreous synechia

• vitreitis = accumulation of cellular debris in vitreous

• leukokoria (16% of cases of childhood leukokoria)

• fever, hepatomegaly, pneumonitis, convulsions

P.346

• peripheral blood eosinophilia

• eye of normal size without calcifications

• secondary retinal detachment

US:

• hypoechoic mass in peripheral fundus

• calcifications

CT:

• intravitreal mass

• focal uveoscleral thickening (granulomatous reaction around larva) with contrast enhancement

• increased density of vitreous cavity

MR:

• enhancing granuloma isointense to vitreous on T1WI

• mass usually hyperintense relative to vitreous on T2WI, occasionally hypointense (due to dense fibroconnective tissue)

Graves Disease of Orbit

• = Thyroid Ophthalmopathy = Endocrine Exophthalmos

• = increase in orbital pressure produces ischemia, edema, fibrosis of muscles

• proptosis

  • Most common cause of uni- / bilateral proptosis in adult!

• lid lag = upper eyelid retraction

• periorbital swelling

• conjunctival injection

• restricted ocular motility (correlates with increase in mean muscle diameters)

• progressive optic neuropathy (5%)

• hyperthyroidism; euthyroidism (in 10 15%); severity of orbital involvement unrelated to degree of thyroid dysfunction

Staging (Werner's modified classification):

Location:

bilateral in 70 85%; single muscle in 10%; asymmetrical involvement in 10 30%; all muscles equally affected with similar proportional enlargements; superior muscle group most commonly when only single muscle involved [former notion: inferior > medial > superior rectus muscle + levator palpebrae > lateral rectus muscle]

• Inferior

• Medial

• Superior

• Lateral

• proptosis = globe protrusion >21 mm anterior to interzygomatic line on axial scans at level of lens

• swelling of muscles maximally in midportion (relative sparing of tendinous insertion at globe) = Coke-bottle sign

• slight uveal-scleral thickening

• apical crowding = orbital apex involved late (pressure on optic nerve)

• dilatation of superior ophthalmic vein (compromised orbital venous drainage at orbital apex due to enlarged extraocular muscles)

• increase in diameter of retrobulbar optic nerve sheath (dural distension due to accumulation of CSF in subarachnoid space with optic neuropathy)

• increased density of orbital fat (late)

• anterior displacement of lacrimal gland

• intracranial fat herniation through superior ophthalmic fissure (best correlation with compressive neuropathy

MR:

• high signal intensity in enlarged eye muscles on T2WI (edema in acute inflammation)

Hemangioma of Orbit

• Most common benign orbital tumor

• sharply demarcated oval mass in superior-temporal portion of conus (2/3) often sparing orbital apex

• displacement (not involvement) of optic nerve

• expansion of bony orbit

• uniform / inhomogeneous (when thrombosed) enhancement

• small calcifications (phleboliths)

• puddling of contrast material on angiography

US:

• well-defined encapsulated mass of intermediate echogenicity

• absent / poor predominantly venous flow

Capillary Hemangioma of Orbit

• proptosis, chemosis (= edema) of eyelid + conjunctiva exaggerated by crying

• associated with skin angioma (90%)

P.347

• mass with enhancement equal to / greater than orbital muscle

• poorly marginated (suggesting malignant cause)

• activity in radionuclide flow studies

US:

• poorly defined heterogeneous mass of intermediate echogenicity

• abundant internal flow decreasing with age

Cavernous Hemangioma of Orbit

• slowly progressive unilateral proptosis, diplopia, diminished visual acuity (optic nerve compression)

Infection of Orbit

• lid edema, ocular pain, ophthalmoplegia

• fever, elevated WBC

Abscess of Orbit

• subperiosteal fluid collection

• displacement of thickened periosteal membrane + increased enhancement

• displacement of adjacent fat + extraocular muscles

MR:

• hyperintensity on T1WI + T2WI

Cellulitis of Orbit

=acute bacterial infection, often extending from paranasal sinuses / eyelids

• limitation of ocular movements

• fever

• proptosis

• scleral thickening

• enlargement + displacement of extraocular muscles (frequently medial rectus muscle)

• increased attenuation of retro-orbital fat + obliteration of fat planes

• opacification of ethmoid + maxillary sinuses (extension through thin lamina papyracea into orbit)

• subperiosteal abscess (with ethmoiditis)

MR:

• hypointense on T1WI + hyperintense on T2WI

• contrast-enhanced fat-suppressed images are most sensitive

US:

• diffuse hypoechoic area invading retrobulbar fat

Preseptal Cellulitis

• =fibrous orbital septum resists extension of infection into posterior compartment of orbit

• thickening of eyelids + septum

• swelling of anterior orbital tissues with increased density + obliteration of fat planes

Edema of Orbit

• swelling of eyelids / face

• increased attenuation of orbital fat + obliteration of fat planes

• displacement + enlargement of extraocular muscles

MR:

• hyperintensity on T2WI

Lymphangioma of Orbit

• proptosis (sudden proptosis from spontaneous intratumoral hemorrhage = CARDINAL FEATURE; exacerbated during upper respiratory infections [rare])

• associated with lesions on lid, conjunctiva, cheek

• coincident lymphangiomatous cysts in oral mucosa

• poorly defined multilobulated inhomogeneous lesion

• single / multiple cystlike areas with rim enhancement (after hemorrhage) = blood cyst = chocolate cyst

• areas of enhancement (= venous channels) / ring enhancement (after hemorrhage)

• rarely contains phleboliths (DDx: hemangioma, orbital varix)

• mild to moderate enlargement of orbit

US:

P.348

• area of predominantly cystic heterogeneous texture with infiltrative borders

MR:

• may show hematoma of various duration within lesion

Lymphoma of Orbit

Usually presents without evidence of systemic disease; subsequent development of systemic disease frequent

• painless swelling of eyelid

• exophthalmos (late in course of disease)

• well-defined high-density mass (most commonly about lacrimal gland)

• diffuse infiltration (tends to involve entire intraconal region)

• slight to moderate enhancement

US:

• solitary / multiple hypoechoic homogeneous masses with infiltrative borders

Metastasis to Orbit

CT:

• small areas of thickening + increased density

• subretinal fluid

Norrie Disease

• = Retinal Dysplasia

• = X-linked recessive disease: ? inherited form of persistent hyperplastic primary vitreous

• seizures, mental retardation (50%)

• hearing loss, deafness by age 4 (30%)

• bilateral leukokoria + microphthalmia

• cataract, blindness (absence of retinal ganglion cells)

  • microphthalmia

  • dense vitreous with blood-fluid level

  • cone-shaped central retinal detachment

  • calcifications

Ocular Trauma

Types:

• Simple / complicated contusion with rupture of ocular wall

• Simple / perforating injury to the globe

• Foreign body

• clinical evaluation: testing of visual acuity, slit-lamp evaluation of cornea + anterior segment, intraocular pressure measurement, funduscopy

US (used if ocular media opaque due to vitreous hemorrhage / hyphema / traumatic cataract)

• Hemorrhage

  • vitreous hemorrhage (53%)

    • visual loss frequent

    • echogenic material moving freely within vitreous chamber during eye movement

    Cx:	retinal detachment (vitreous traction secondary to fibrovascular ingrowth following hemorrhage)
    Rx:	vitrectomy

  • retrohyaloid hemorrhage (2%)

    • echogenic material remaining behind detached vitreous capsule during eye movement

  • hematoma in retro-ocular space

• Retinal detachment

  • total retinal detachment (18%)

    • slightly thick line of V shape with apex at optic disk

    • retina remains bound down at ora serrata

  • focal retinal detachment (2%)

    • elevated immobile line close to sclera at periphery of globe

• 3. Vitreous detachment (11%)

  • thin undulate mobile line moving away from posterior aspect of globe during eye motion

• 4. Choroidal detachment (5%)

• 5. Intraocular foreign body (7%)

  US sensitivity:	95% for intraocular + 50% for intraorbital foreign body
  Cx:	siderosis (if metallic); endophthalmitis

• 6. Lens dislocation (3%)

• 7. Thickening / rupture of ocular wall

• 8. Vascular complications

  • central renal artery occlusion

  • carotid-cavernous fistula

  • fistula of angular vein

Optic drusen

• = accretions of hyaline material on / near surface of optic disc; often familial

• headache, visual field defects

• pseudopapilledema

• small flat / round calcification at junction of retina + optic nerve bilateral in 75%

Optic pathway glioma

• = Juvenile pilocytic astrocytoma = optic nerve glioma

• = most common cause of optic nerve enlargement

P.349

• decreased visual acuity / visual-field defect

• axial proptosis with larger masses

• optic disk pallor, optic nerve atrophy (axonal damage)

• spasmus nutans (= high-frequency nystagmus of low amplitude associated with head nodding movement)

• precocious puberty (in 39% of only NF1 patients)

• tubular / fusiform / excrescentic well-circumscribed homogeneous enlargement of optic nerve-sheath complex:

  CHARACTERISTIC kinking / buckling of nerve

• posterior extension to involve chiasm + hypothalamus in 25 60% (indicates nonresectability)

• calcifications (rare)

• same attenuation as normal optic nerve; slight contrast enhancement

• ipsilateral optic canal enlargement (90%) >3 mm / 1 mm difference compared with contralateral side

US:

• well-defined homogeneous mass of medium echogenicity inseparable from optic nerve

Malignant Optic Glioma of Adulthood

• rapidly progressive monocular visual loss culminating in monocular blindness within a few weeks

• with retrograde tumor extension: contralateral temporal hemianopia, polyuria, polydipsia

• focal / diffuse enlargement of optic nerve

• hypo- to isointense on T1WI + hyperintense on T2WI

• obliteration of subarachnoid space around affected portion of nerve

• diffuse intense enhancement of optic nerve

• thickening + abnormal enhancement of optic nerve sheath

Optic Nerve Sheath Meningioma

= Perioptic Meningioma

• insidious onset of progressive loss of visual acuity over months (optic atrophy), proptosis

• retinal examination:

  • papilledema

  • optociliary veins = dilated connections between ciliary circulation + central retinal vessels

• optic atrophy

Location:

• orbit = optic nerve sheath meningioma

• in optic canal = intracanalicular meningioma

• intracranial opening of optic canal = foraminal meningioma

• middle cranial fossa

• tubular (most commonly) / fusiform / excrescentic thickening of optic nerve

• calcifications in 20 50% (HIGHLY SUGGESTIVE)

• enlargement of optic canal

• sphenoid bone hyperostosis

US:

• hypoechoic tumor with irregular border

CECT: enhancement is the rule

• tumor enhancement around nonenhancing optic n.:

  • tram-track sign on axial view

  • ringlike / doughnut configuration on coronal view

  • linear high-attenuation area parallel to optic nerve (= tumor spread along subarachnoid space)

• minimal extension into optic canal (not uncommon)

MR:

• hypointense to fat on T1WI

• iso- to slightly hyperintense relative to optic nerve on T2WI

• tram-track sign = intensely enhancing extrinsic soft-tissue mass surrounding optic nerve on fat-suppressed T1WI

Optic Neuritis

= nerve involvement by inflammation, degeneration, demyelination

Etiology:

• Multiple sclerosis (involves optic nerve in 1/3)

• Inflammation secondary to ocular infection

• Degeneration (toxic, metabolic, nutritional)

• Ischemia

• Meningitis / encephalitis

  • 45 80% of patients develop multiple sclerosis within 15 years of their first episode of optic neuritis!

• ipsilateral orbital pain on eye movement

• sudden onset of unilateral loss of vision over several hours to several days

CT:

• normal / mildly enlarged optic nerve + chiasm

P.350

• may show enhancement

MR:

• mild enlargement + enhancement of optic nerve well demonstrated on axial T1WI

Perioptic Neuritis

• Multiple sclerosis

• Infection: measles, mumps, syphilis

• Sarcoidosis

• leptomeningeal enhancement obscures lucent optic nerve

Persistent Hyperplastic Primary Vitreous

= rare condition with persistence + proliferation of embryonic hyaloid vascular system of primary vitreous due to arrest of normal regression

Bilaterality is a feature of a congenital syndrome (Norrie disease, Warburg disease)!

• Primary vitreous

  • = fibrillar ectodermal meshwork + mesodermal tissue consisting of embryonic hyaloid vascular system; appears during 1st month of life; extends between lens + retina; involutes by 6th month of gestation

• Hyaloid artery

  • = important source of intraocular nutrition until 8th month of gestation; arises from dorsal ophthalmic artery at 3rd week of gestation; grows anteriorly with branches supplying vitreous + posterior aspect of lens

• Secondary / adult vitreous

  • begins to form during 3rd gestational month; a watery mass of loose collagen fibers + hyaluronic acid gradually replaces primary vitreous, which is reduced to a small S-shaped remnant (hyaloid canal = Cloquet canal) and serves as lymph channel

• unilateral leukokoria (2nd most common cause) [2 3% of leukokoria cases]

• seizures, mental deficiency, hearing loss

• cataract

• ophthalmoscopy: S-shaped tubular mass extending between posterior surface of lens + region of optic nerve head; lens opacity may preclude diagnosis

  • microphthalmia = small hypoplastic globe

  • retinal detachment (due to vitreoretinal traction in 30%)

US:

• hyperechoic band extending from posterior pole of globe to posterior surface of lens (= embryonic rest of primary vitreous)

• central anechoic line (= persistent hyaloid artery) visible in cases of echogenic vitreous hemorrhage

• hyperechoic band extending from papilla to ora serrata (= retinal detachment)

CT:

• enhancing cone-shaped central retrolental density extending from lens through vitreous body to back of orbit, just lateral to optic nerve

• small optic nerve

• deformity of globe + lens

• hyperdense vitreous (from previous hemorrhage)

• fluid-fluid levels from breakdown of recurrent hemorrhage in subhyaloid (between vitreous + retina) / subretinal space (between sensory + pigment epithelium)

• NO calcifications

MR:

• hyperintense vitreous body on T1WI + T2WI from chronic blood degradation products (methemoglobin) / proteinaceous fluid

• hypo- to isointense thin triangular band with base near optic disc and apex at posterior surface of lens

• marked enhancement of fibrovascular mass within vitreous

Cx:

• Glaucoma, cataract from recurrent spontaneous intravitreal hemorrhage (due to friable vessels)

• Proliferation of embryonic tissue

• Retinal detachment from organizing hemorrhage / traction

• Hydrops / atrophy of globe + resorption of lens

• Phthisis bulbi (scarred shrunken eye)

Pseudotumor of Orbit

• = Idiopathic Inflammatory Pseudotumor

• = nongranulomatous inflammatory process affecting all intraorbital soft tissues

Etiology:

• cause not apparent at time of study: bacterial, viral, foreign body

• systemic disease presently not apparent: sarcoidosis, collagen, endocrine

• idiopathic: probably abnormal immune response

• unilateral painful ophthalmoplegia

• proptosis, chemosis, lid injection

• impaired ocular movement

• tumefactive type (common)

  • discrete / poorly defined intra- / extraconal mass = pseudotumor close to surface margin of globe

• myositic type (unusual)

  • enlargement of one / more extraocular muscles close to insertion in globe with ill-defined margins

  • typically involves muscles + tendon insertions (DDx to Graves disease with muscle involvement only)

• inflammatory stranding of retrobulbar fat (may involve anterior compartment)

• uveoscleral thickening and enhancement (sclera near Tenon capsule)

• orbital muscle thickening

P.351

• enhancement of optic nerve sheath

• enlarged lacrimal gland

• proptosis

MR:

• lesion isointense to fat on T2WI

Prognosis:

• (1) remitting / chronic + progressive course

• (2) rapid dramatic + lasting response to steroid therapy

DDx:

• Lymphoma (may be confused with lymphoma clinically, radiographically, pathologically)

• Thyroid ophthalmopathy (tapering of distal muscles, painless proptosis)

• Radiation therapy

Retinal Astrocytoma

= low-grade neoplasm / hamartoma arising from the nerve fiber layer of retina / optic nerve, usually associated with tuberous sclerosis

• leukokoria (3% of all childhood cases of leukokoria)

• asymptomatic, progressive loss of vision

Retinal Detachment

Cause: trauma, tumor, exudative / inflammatory process, scar

US:

• curvilinear area of high echogenicity fixed at optic disk (= papilla) + extending to ora serrata

• V-shaped (with total detachment)

• in one quadrant only (partial detachment)

• thick folded retina with loss of mobility (long-standing detachment)

• subretinal space normal / occupied by blood, inflammation / tumor (depending on cause)

DDx: vitreous membranes, choroidal detachment (point of fixation not at papilla)

Retinoblastoma

= rare malignant congenital intraocular tumor arising from primitive photoreceptor cells of retina (included in primitive neuroectodermal tumor group)

Types:

• Nonheritable form (66%)

  • Sporadic postzygotic somatic mutation (subsequent generations unaffected)

    Mean age at presentation:

    23 months unilateral disease

  • Chromosomal anomaly

    • = monosomy 13 / deletions of 13q

    Associated with:

    microcephaly, ear changes, facial dysmorphism, mental retardation, finger + toe abnormalities, malformation of genitalia

• Heritable form

  • Heritable sporadic form (20 25%)

    • = sporadic germinal mutation (50% chance to occur in subsequent generations)

    Mean age at presentation:

    12 months bilateral retinoblastomas in 66%

  • Familial retinoblastoma (5 10%)

    • = autosomal dominant with abnormality of band 14 in chromosome 13 (95% penetrance)

    • Mean age at presentation: 8 months

    • usually 3 to 5 ocular tumors per eye

    • bilateral tumors in 66%

    • Risk of secondary nonocular malignancy:

    • osteo~, chondro~, fibrosarcoma, malignant fibrous histiocytoma (20% risk within 10 years, >90% by 30 years of age)

    • Trilateral retinoblastoma (rare variant)

      • = bilateral retinoblastomas + neuroectodermal pineal tumor (pineoblastoma)

    • Quadrilateral retinoblastoma

      • = trilateral retinoblastoma + 4th focus in suprasellar cistern

Histo:

• Flexner-Wintersteiner rosettes (in 50%)

  • = neuronal cells line up around an empty central zone filled with polysaccharides

    • Very specific for retinoblastomas!

• Homer-Wright rosettes

  • = neuronal cells line up around a central area containing a cobweb of filaments (also found in other primitive neuroectodermal tumors)

• fleurettes

  • = flowerlike groupings of tumor cells that form photoreceptor elements (specific for retinal differentiation)

• cat's eye = leukokoria (whitish mass behind lens) in 60%

  • About 50% of all childhood leukokoria are caused by retinoblastoma!

• decreased visual acuity, heterochromia iridis

• strabismus (crossed eyes), proptosis (less common)

• hyphema

• iris neovascularization, phthisis bulbi

P.352

• ocular pain from secondary angle-closure glaucoma

normal ocular size

US:

• heterogeneous hyperechoic solid intraocular mass

• cystic appearance upon tumor necrosis

• secondary retinal detachment in all cases

• acoustic shadowing (in 75%)

• vitreous hemorrhage frequent

CT:

• solid smoothly marginated lobulated retrolental hyperdense mass in endophytic type (rarer exophytic type grows subretinally causing retinal detachment)

• partial punctate / nodular calcification (50 75 95%)

  • Retinoblastoma is the most common cause of orbital calcifications!

• dense vitreous (common)

• extraocular extension (in 25%): optic nerve enlargement, abnormal soft tissue in orbit, intracranial extension

• contrast enhancement usual

• macrophthalmia

MR:

• iso- to mildly hyperintense tumor on T1WI relative to vitreous + moderate to marked enhancement

• distinctly hypointense on T2WI (similar to uveal melanoma)

• subretinal exudate usually hyperintense on T1WI + T2WI (proteinaceous fluid)

Mortality:

• choroidal invasion: 65% if significant, 24% if slight

• optic nerve invasion:

  • <10% if not invaded

  • 15% if through lamina cribrosa

  • 44% if significantly posterior to lamina cribrosa

• margin of resection not free of tumor: >65%

DDx:

• Retinoma = retinocytoma (benign variant)

• Toxocara canis infection (no calcification)

• Retrolental fibroplasia (microphthalmia)

• Coats disease (subretinal exudation, no calcification)

• Norrie disease (retinal dysplasia)

• Persistent hyperplastic primary vitreous (hypoplastic globe, no calcification)

Retrolental Fibroplasia

• = Retinopathy of Prematurity

• = bilateral often asymmetric postnatal fibrovascular organization of vitreous humor, which usually leads to retinal detachment

Pathophysiology:

• retinal vascularization occurs in 4th 9th months of fetal life progressing from the papilla to the periphery; vascularization is incomplete in premature neonates especially in temporal sectors

Predisposed: premature infants with respiratory distress syndrome requiring prolonged oxygen therapy

Severity directly related to:

• degree of prematurity

• birth weight

• amount of oxygen used in therapy

• leukokoria in severe cases (traction retinal detachment, usually bilateral + temporal) [3 5% of all childhood leukokoria cases]

• Ophthalmoscopic stages:

  1st stage	=	arteriolar narrowing of most immature vessels at the border of the vascular-avascular retina (from spasm as a reaction to hyperoxygenation)
  2nd stage	=	dilatation + elongation + tortuosity of retinal vessels (after oxygen withdrawal)
  3rd stage	=	retinal neovascularization with growth into vitreous leads to vitreous hemorrhage
  4th stage	=	fibrosis with retraction of fibrovascular tissue + retinal detachment

  bilateral microphthalmia retinal detachment

US:

• hyperechoic tracts extending from temporal side of periphery of retina to vitreous behind the lens

CT:

• dense vitreous bilaterally (neovascular ingrowth)

• dystrophic calcifications in choroid + lens (late stage)

MR:

• hyperintense vitreous on T1WI + T2WI (from chronic subretinal hemorrhage)

• hypointense retrolental mass (apposition of detached leaves of retina displaced from retinal pigment layer)

Prognosis:

• spontaneous regression of vitreous neovascularization (85 95%) retinal detachment

• progression to cicatricial stage characterized by formation of dense membrane of gray-white vascularized tissue in retrolental vitreous + retinal detachment + microphthalmia

DDx: Retinoblastoma (calcifications in eye of normal size)

Rhabdomyosarcoma

Most common primary malignant orbital tumor in childhood

• 10% occur primarily in orbit

• 10% metastasize to / invade orbit

• rapidly progressive exophthalmos + proptosis of upper lid

• large soft-tissue density mass with ill-defined margins (extraocular muscles not involved)

• extension into preseptal space, adjacent sinus, nasal cavity, intracranial cavity with bony erosion

P.353

• may show significant enhancement

US:

• heterogeneous well-defined irregular mass of low to medium echogenicity

Staphyloma

= sacculation of posterior pole of globe (or berrylike protrusion of cornea)

Uveal Melanoma

Most common primary intraocular neoplasm in adult Caucasian

• retinal detachment, vitreous hemorrhage

• astigmatism, glaucoma

US:

• small flat hyperechoic solid mass

CT:

• ill-defined hyperdense thickening of wall of globe with inward bulge

MR:

• sharply circumscribed hyperintense lesion on T1WI (paramagnetic properties of melanin)

Varix of Orbit

Etiology:

• Congenital: venous malformation / venous wall weakness

• Acquired: intraorbital / intracranial AVM

• intermittent exophthalmos associated with straining

• frequent blindness

• involvement of superior / inferior orbital vein; phleboliths rare

• may produce bony erosion without sclerotic reaction

• enlargement of mass during Valsalva maneuver / jugular vein compression

• well-defined markedly enhancing mass

• spontaneous thrombosis (common)

US:

• anechoic tubular / oval structure thrombus

• venous flow increasing with Valsalva

MR:

• flow void (rapid flow) / flow-related enhancement (slow flow)

Warburg Disease

= autosomal recessive syndrome characterized by

• bilateral persistent hyperplastic primary vitreous

• hydrocephalus, lissencephaly

• mental retardation

• bilateral leukokoria + microphthalmia