The Orbit

Thorsang R1 Neuroradiology topic

04.06.2014

Outline

• Orbit overview

• Imaging techniques

• Orbital anatomy

• Diseases of the orbit

Major anatomic components

• Globe

• Optic nerve & sheath

• Conal-intraconal area

• Extraconal area

Differential diagnoses

Imaging techniques

MRI

• Initial imaging sequence of choice for the orbit and CN II – Intraaxial, sellar, parasellar

lesions

– More sensitive

CT

• An adjunctive tool: calcifications

– Small meningioma

– Retinoblastoma with calcification

Imaging techniques

Orbital anatomy

• Roof

• Floor

• Medial wall

• Lateral wall

• Superior orbital fissure

• Inferior orbital fissure

• Optic canal

Orbital roof

• Frontal bone with frontal sinus

• Anteriorly thin

• Fossa for lacrimal gland

Orbital floor

• Orbital plate of maxilla – Thin

-> blowout fx*

• Orbital process of palatine bone

• Orbital surface of zygomatic bone

Medial orbital wall

• Lacrimal groove • Lamina

papyracea – Medial blowout

fracture* – Spontaneous

dehiscence of orbital fat • Into ethmoid

sinus

• Sphenoid bone

Lateral orbital wall

• Orbital surface of zygomatic bone

Superior orbital fissure

Location

• Between roof and lateral wall

• Surrounded by sphenoid

• Beneath optic canal

• Optic strut

Superior orbital fissure

Content • Superior

opthalmic vein • CN III, IV, VI • CN V1

>> Conduit between orbital apex-cavernous sinus

Inferior orbital fissure

Location

• Between floor and lateral wall

• PPF fossa-NSP masticator space

Inferior orbital fissure

Content • CN V2, V3 • N.

– from PP gg.

• V. – inf. Opthalmic v.-

pterygoid plexus

>> Deep face inflammatory and neoplastic lesions

Optic canal

• Lesser wing of sphenoid bone

• Optic nerve + ophthalmic artery (in dural shealth)

• From suprasellar cistern

Conal-intraconal area

Intraconal space pathology

• Venous vascular malformation • Capillary hemangioma • Venous dilatation

– Carotid Cavernous Fistula – Varices

• Optic nerve lesions – Optic neuritis

• MS • Devic's syndrome • Neuritis due to infection

(e.g.herpes zoster) • Autoimmune (e.g.Lupus) • Drugs (e.g.chloramphenicol,

ethambutol)

– Optic nerve glioma – Optic nerve meningioma – Pseudotumor

• Other cranial nerves – Schwannoma of 3rd, 4th and

6th cranial nerve

Conal space pathology

• Thyroid eye disease – usually enlargement of the inferior and medial rectus

• Pseudotumor: – idiopathic orbital inflammation

• Adjacent inflammation: – sinusitis

• Uncommon causes of enlargement of the extra-ocular muscles – glycogen storage disease and lymphoma

Extraconal area

• Fat

• Lacrimal gland

– Lens-shape

– Anterior, superolateral

– Lies on levator palpabrae and lateral rectus

• Bone

Extraconal pathology

• Abscess due to sinusitis

• Schwannoma of the V1 and V2

• Bone lesions:

– Fibrous dysplasia of the sphenoid wing

– Metastases

– Multiple myeloma

• Diseases of the orbital appendages

Orbital appendages

• Lacrimal gland

– superolaterally in the orbit

– granulomatous, epithelial/glandular, and developmental

• lacrimal sac

• lacrimal duct

– -> inferior terbinate into the nose

Diseases of the orbit

• Globe

• Optic nerve & sheath

• Conal-intraconal area

• Extraconal area

The ocular space • Anterior chamber:

cornea anteriorly and the lens and iris posteriorly – Rupture of the globe – Hemorrhage: also known as anterior hyphema – Cataract – Keratitis: inflammation of the cornea – Periorbital cellulitis

• Posterior chamber: posterior to the iris – Glaucoma – Uveitis – Ciliary melanoma

The globe

The globe

Vitreous body posterior to the lens

– Rupture

– Hemorrhage

– CMV infection: especially in HIV

– Persistent Hyperplastic Primary Vitreous (PHPV)

Persistent hyperplastic primary vitreous

• Unilateral leukokoria in male infants

• Persistent hyaloid canal

• Persistence of the primary vascular vitreous

• Hyperplasia of the residual embryonic connective tissue

• PHPV is the second most common cause of leukocoria

• Also develops glaucoma and cataract

• Findings:

– Microphtalmic globe with enhancing increased density in the vitreous humor.

– Unilateral/bilateral tissue density band from back of the lens to the posterior inner globe (Persistent Cloquet’s canal)

– Retinal detachment (occurs in 30-55%)

Persistent hyperplastic primary vitreous

Persistent hyperplastic primary vitreous

The globe

Retina

• Retinoblastoma:

– a common tumor in children

• Hemangioblastoma:

– most common retinal tumor in the adult

– von Hippel Lindau disease

• Detachment:

– most common retinal lesion

– diabetic retinopathy

Retinoblastoma

• Common tumor in the first year of life

• Child < 3 years of age (98%)

• Other presentations: leukokoria, strabismus, decreased visual acuity, family hx, eye pain, proptosis

• Believed to arise from neuroectodermal cells

• 75% unilateral; 25% bilateral

• All bilateral cases are hereditary (AD) >> deficient tumor suppression gene on chromosome 13

• 90% calcified

Retinoblastoma

Retinoblastoma

• The other tumors in this age group are

– Neuroblastoma

– Wilm's tumor

– Leukemia

– Teratoma.

Retinoblastoma

• Techniques – CT is prefered to detect calcification

– MR serves an adjunctive role

• Findings: – CT: an intraocular mass with calcification

in a child<3 yr -> should consider retinoblastoma

– Extraocular spreading along the optic nerve

– Together with pinealoma -> trilateral retinoblastoma

Retinoblastoma

DDx in a child with leukokoria

• Toxocara endophthalmitis

• Persistent hyperplastic vitreous

• Retinopathy of prematurity

• Coat’s disease

Calcifications

• In adults

– most common at the annulus of Zinn

– at the optic nerve head within the eye -> optic disc drusen (asymptomatic, but pseudo-papilledema from PE)

• In children

– retinoblastoma until proven otherwise

Coat’s disease

• A rare eye disorder: congenital non-hereditary vascular malformation of the retina – multiple telangiectatic vessels -> exudate leakage ->

retinal detachment

• A 6-to-8-year-old boy with unilateral leukokoria

• Symptoms occurs when the retina detaches -> central visual loss

• Findings: – Increased density of the vitreous

– Normal globe size, lack of calcification

Coat’s disease

Choroid

• Melanoma:

– choroid contains the melanin cells

• Metastases:

– choroid is the most vascular structure in the eye

• Detachment:

– usually post-traumatic

Uveal melanoma

• The most common primary intraocular malignancy in adult

• A 50-to-70-year old with unilateral ocular complaint

• 85% from choroid, 9% from ciliary body, and 6% from iris

• Dx from PE + U/S

• CT/MR when opaque ocular media prevents a clear view

Uveal melanoma

– Findings

• Soft tissue mass adjacent to outer layer of the globe that bulges inward toward the vitreous

• Mushroom cloud appearance

• Hyperintense on T1 and hypointense on T2

Sclera

• Infection:

– Sinusitis

– Viral

• Pseudotumor

• Detachment

Scleritis

• granulomatous inflammatory disorder

• Erythema and chemosis

• Characteristics – optic disk edema

– exudative retinal detachment

– Choroidal folds and scleral thickening >> elevated mass

• Findings: – CT:

• thickened posterior sclera, may enhanced

• Thickening of extraocular muscles can also be seen

– Magnetic resonance imaging

• nodular elevation into the vitreous

• Iso-to-hyperintense to normal sclera on T1

• Hypointense on T2

• moderate to marked inhomogeneous enhancement with Gd

• A retinal detachment appears as a crescent-shaped area that is hyperintense on both T1 and T2

Scleritis

T1 fs + C

• collapsed globe (flat tire appearance)

Globe Rupture

• presence of intra-ocular air or a foreign body

• thick posterior sclera

• hazy outline of the globe

• enlarged anterior chamber

Globe Rupture

Retinal and choroidal detachment

• Retinal epithelium ends at the ora serrata

– > retinal detachment will not go beneath it

• Retinal detachment with hemorrhage

– adults with DM and HTN

– shaken baby syndrome

• Choroidal detachment

– recent intraocular surgery

– trauma

Detachment

Retinal Choroidal

Retinal

Choroidal

Coloboma

• A congenital globe defect, usually at the optic nerve insertion point

• Often there is microphtalmia and the eye protrudes inferiorly.

• 10% also have other CNS anomalies.

• Findings: – a small globe with a cystic outpouching of vitreous

at the optic nerve attachment site.

– Retroocular cyst

Coloboma

• Coloboma can be part of the CHARGE syndrome: – Coloboma – Heart anomalies – choanal Atresia – Retardation of growth and development – Genital and Ear anomalies.

• Coloboma can also be part of the COACH syndrome:

– Cerebellar vermis hypoplasia, – Oligophrenia (MR) – congenital Ataxia – Coloboma – Hepatic fibrosis.

Diseases of the obit

• Globe

• Optic nerve & sheath

• Conal-intraconal area

• Extraconal area

Optic neuritis

• Presentations – Visual loss over hours to days

– Pain on movement and tenderness when pressure applied to globe

• Sporadic/multiple sclerosis – If found, T2 whole brain should be done

• Less common causes – pseudotumor, sarcoidosis, radiation, viral, TB,

syphilis neuritis

Optic neuritis

Multiple sclerosis

Devic's syndrome

• Neuromyelitis optica

Optic nerve/sheath tumor

• Optic nerve sheath meningioma

• Optic nerve glioma

Meningioma

• The most common optic nerve sheath tumor • ischemic neuropathy due to venous obstruction • progressive visual loss, papilledema, optic atrophy, pale disc • Strong association with NF-2 • Abnormal enhancement of the optic nerve sheath • Calcifications 20-50%

Abnormal enhancement of the optic nerve sheath

Optic nerve glioma

• Juvenile pilocytic astrocytomas WHO type 1 • Anywhere along the optic tract from the occipital

region to the chiasm and the optic nerve

• 50% of optic nerve glioma have NF1. • Only 10% of NF1 have optic nerve glioma. • Less commonly cystic in NF than in non-NF

• Age 4-5 years and only 20% of patients have

visual symptoms.

Neurofibromatosis type I

At least 2 of • Six cafe au lait macules • Two neurofibromas of any type or 1 plexiform neurofibroma • Multiple freckles in the axillary or inguinal region • Bone dysplasia • Optic glioma • Two or more iris hamartomas (Lisch nodules) • A first-degree relative with NF1

Optic nerve glioma

T2 T1fs + Gd

Diseases of the obit

• Globe

• Optic nerve & sheath

• Conal-intraconal area

• Extraconal area

Thyroid opthalmopathy

• Compressive optic neuropathy

– Direct compression by the muscles

– Ischemic by compression of the vessels

Idiopathic inflammatory pseudotumor

• Idiopathic inflammation of the orbit

• Any part of the orbit: muscles, tendons, fat, optic nerve, nerve sheet, lacrimal gland

Pseudotumor

Thyroid eye Pseudotumor

Diseases of the obit

• Globe

• Optic nerve & sheath

• Conal-intraconal area

• Extraconal area

Periorbital abscess

Periorbital abscess

• Complications

– Venous thrombosis of the superior and inferior ophthalmic vein

– Cavernous sinus thrombosis and cavernous-carotid fistula in certain fungal sinusitis (e.g.aspergillosis)

Orbital and periorbital cellulitis

• A 'red hot eye' and proptosis

• Orbital VS periorbital cellulitis -> >> the orbital septum <<

• Periorbital cellulitis – The orbital septum and the superficial part

– OPD—PO ATB

• Orbital cellulitis – the structures posterior to the septum are also involved.

– IPD--IV ATB

Orbital cellulitis

Proptosis with sphenoid wing lesion

Four sphenoid wing lesions that can cause proptosis:

• Fibrous dysplasia

• Paget's disease

• Meningioma with hyperostosis of the sphenoid wing

Orbital appendages

• Lacrimal gland

• lacrimal sac

• lacrimal duct

Lesions of the lacrimal gland

• Inflammation

– The most common lesions of the lacrimal gland

– i.e. Sjoegren's, TB, fungus, pseudotumor

– Do not cause masses

Children

– congenital obstructions of the valves in the lacrimal duct -> dacryocystoceles

adults

– strictures from ethmoid sinusitis or stones -> epiphera or increased tearing

Dacryocystocele

• Lacrimal gland mass

– Lymphoma

– Pleomorphic adenoma

– Epithelial tumors (adenoid cystic tumor)

Lesions of the lacrimal gland

Tumors

• Epidermoid and dermoid tumors

– Developmental

– Usually arises anteriorly between the globe and orbital periosteum

– Well-circumscribed cystic masses containing debris

– Dermoid may contain fat, teeth, and hair

Vascular malformation

• Carotid cavernous sinus fistula

• Cavernous hemangioma

• Capillary hemangioma

• Lymphangioma

Carotid cavernous sinus fistula

Cavernous carotid a.

—cavernous sinus

Capillary hemangioma

• 6-12 months of age • Involutional at 5-7 years of age • Mostly skin, but also in the extraconal of the eye • PHACE-syndrome:

– Posterior fossa malformations, – Hemangiomas – Arterial anomalies – Cardiac malformation – Eye abnormalities such as coloboma, glaucoma

• CT—irregular margin

Capillary hemangioma

Venous vascular malformations

• The most common intraconal mass in an adult

• 45-year-old women with slow progressive proptosis, diplopia, visual loss

• Most are unilocular

• CT – Phleboliths

– sharply circumscribed, round, dense mass

– Spare apex

– Bony erosion

Venous vascular malformation

lymphatic malformation

• Lymphangioma • Childhood onset (60% before 16 y/o) • May abruptly hemorrhage resulting in fluid-fluid

levels • May be extraconal or multicompartmental • Association with intracranial malformations

– Turner's – fetal alcohol syndrome

• Absence of contrast enhancement in pure lymphatic lesions

lymphatic malformation

orbital varix

• Propulsion of the eye during straining

• During valsalva -> extreme dilation

Valsalva

Conclusion

• Orbital anatomy

• Disease approach

• Diseases of the orbit

Approach to diseases

• Globe

• Optic nerve & sheath

• Conal-intraconal area

• Extraconal area

The globe

Disease approach

Q & A

References

• Harnsberger, H. Ric., and H. Ric. Harnsberger. Handbook of Head and Neck Imaging. St. Louis: Mosby, 1995. Print.

• Grossman, Robert I., and David M. Yousem. Neuroradiology. Philadelphia, PA: Mosby Elsevier, 2010. Print.

• "Orbita - Pathology." The Radiology Assistant :. N.p., n.d. Web. 20 May 2014

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