Orbit(Handbook Of Head And Neck P 301-339)

Front 1

What four major anatomic areas are used to subdivide the orbit when constructing a differential diagnosis?

Back 1

1. Globe
2. Optic Nerve and Sheath
3. Conal-Intraconal area
4. Extra-conal area

Front 2

Along what scan plane is the orbit best imaged in the axial direction by CT or MRI?

Back 2

A plan along the anthropologic baseline or infraorbitomeatal line, because imaging in this plane closely parallels the orbital axis(permitting visualization of the optic nerve and horizontal eye muscles)

Front 3

The main portion of the triangular orbital room is comprised of the?(p 310-311 figure 14-1 and 14-2)

Back 3

Frontal bone, with the frontal sinus within

Front 4

The anterolateral part of the orbital roof forms a shallow fossa for the?

Back 4

Lacrimal gland

Front 5

The orbital roof can be imaged completely only in what plane(axial, sagittal, coronal)?

Back 5

Coronal

Front 6

What is the shape of the orbital floor?

Back 6

Triangular

Front 7

What bones form the floor of the orbit?

Back 7

1. Orbital plate of the maxilla
2. Orbital process of the palatine bone
3. Orbital surface of the Zygomatic bone

Front 8

Where do inferior blowout fractures usually occur?

Back 8

Orbital plate of the maxilla, because it's quite thin

Front 9

Anterior aspect of the medial orbital wall is formed by?

Back 9

The frontal process of the maxillary bone(together with the lacrimal bone the frontal process of the maxillary bone forms the lacrimal fossa)

Front 10

What can mimic a medial orbital blowout fracture?

Back 10

Spontaneous dehiscence of the orbital flate occuring through the lamina papyracea into the ethmoid sinus.

Front 11

What forms the posterior portion of the medial orbital wall?

Back 11

A small portion of the sphenoid bone.

Front 12

Anteriorportion of the lateral orbital wall is formed by the?

Back 12

Orbital surface of the zygomatic bone.

Front 13

Where does the superior orbital fissure sit?

Back 13

At the margin between the lateral wall and orbital roof.

Front 14

The superior orbital fisure has what bone as its lateral and medial borders?

Back 14

Lateral border(greater wing of the sphenoid)
Medial border(lesser wing of the sphenoid)

Front 15

Where does the medial tip of the superior orbital fissure lie?

Back 15

Beneath the optic canal

Front 16

How is the superior orbital fissure separated from the optic canal?

Back 16

By the optic strut

Front 17

What is the optic strut?

Back 17

A bridge of bone formed by the lesser wing of the spenoid, separates the superior orbital fissure from the optic canal.

Front 18

Superior orbital fissure contents(3)

Back 18

1. Superior ophthalmic vein.
2. CN III, CN IV, CN VI
3. V1(Ophthalmic portion trigeminal)

Front 19

What can the superior orbital fissure be a conduit for?

Back 19

for inflammatory or neoplastic dz between the orbital apex and cavernous sinus(intracranial structure)

Front 20

Where is the inferior orbital fissure?

Back 20

Between the floor and lateral wall of the orbit.

Front 21

What does the inferior orbital fissure connect with?

Back 21

The pterygopalatine fossa and nasopharyngeal masticator space(intfratemporal fossa) inferolaterally
- Deep face inflammatory and neoplastic lesions can gain access to the orbital apex)

Front 22

Contents of the inferior orbital fissure?

Back 22

Infraorbital and zygomatic nerves
Nerves from pterygopalatine ganglion
Venous connections between inferior opththalmic vein and pterygoid plexus

Front 23

What is the optic canal formed by?

Back 23

Completely formed by the lesser wing of the sphenoid.

Front 24

The optic canal contains?

Back 24

Optic Nerve
Ophthalmic artery
(both of which are contained in a dural sheath)

Front 25

The sphere of the globe is divided into the anterior and posterior segments by?

Back 25

The lens

Front 26

Three segments of the Optic nerve sheath

Back 26

1. Orbital
2. Canalicular
3. Intracranial

Front 27

How long is the optic nerve?

Back 27

4.5 cm, with the orbital segment is the longest

Front 28

What is the ring of Zinn?

Back 28

Tendinous ring that encloses the central portion of the superior orbital fissure and optic foramen made up of the 4 rectus muscles

Front 29

What passes through the ring of Zinn?

Back 29

Optic nerve/sheath complex,
Ophthalmic artery
Distal aspects of CN III and VI

Front 30

Where does the superior ophthalmic vein exit the orbit?

Back 30

Through he superior orbital fissure.

Front 31

What is contained in the extraconal region(between the muscle cone and bony orbit?

Back 31

Only fat and the lacrimal gland.

Front 32

Describe the lacrimbal gland
(shape/location)

Back 32

lens-shaped organ located in the anterior orbit superolateral to the globe.

Front 33

Definition of microphthalmia.

Back 33

Congenital underdevelopment or acquired diminution in the size of the globe.

Front 34

What diseases can you see bilateral micropthalmia in younger patients?

Back 34

Congenital rubella
Persistent hyperplastic vitreous
Retinopathy of prematurity
Retinal folds
Lowe Syndrome

Front 35

What diseases can you see bilateral micropthalmia in older patients?

Back 35

Trauma
Surgery
Inflammation with disorganization of the eye(phthisis bulbi)

Front 36

Congenital vs. acquired micropthalmia - radiologic characteristics

Back 36

Congenital - small globe associated with a small, poorly developed bony orbit
Acquired (normal orbit, shrunken, calcified globe)

Front 37

Macrophthalmia definition

Back 37

Enlargement of the globe.

Front 38

Causes of Macrophthalmia

Back 38

Juvenile glaucoma or myopia

Front 39

Definition of Coloboma

Back 39

Congenital defect in the globe, usually at the point of insertion of the optic nerve.
(represents a localized defect in the sclera, uvea, and retina)

Front 40

What does a CT/MR show in coloboma?

Back 40

a small globe with a cystic outpouching of vitreous at the sate of attachment of the optic nerve to the globe

Front 41

Clinical presentation of hyperplastic primary vitreous?

Back 41

Unilateral leukokoria in male infants, which may simulate retinoblastoma.

Front 42

Pathologic features of hyperplastic primary vitreous

Back 42

1. Persistecne of primary vascular vitreous which normally undergoes involution by the sixth embryonic month.
2. Hyperplasia of the residual embryonic connective tissue occurs after involution

Front 43

Persistent hyperplastic primary features?

Back 43

- Microphthalmic globe with enhancing, increased density in the vitreous humor
- a tissue density band may extend from the back of the lens to the posterior inner surface of the globe.

Front 44

Retinopathy of Prematurity - patholigic features?

Back 44

abnormal proliferation of retinal vascular buds, often a/w use of high concentrations of oxygen for premature infants in neonatal ICUs(due to long term vent support)

Front 45

Retinopathy of prematurity
(Radiologic features)

Back 45

Increased density in the vitreous bilaterally

Front 46

Coat's dx (clinical presentation)

Back 46

Unilateral leukokoria in a 6-8 year old boy.

Front 47

Coat's dx (pathologic feature)

Back 47

Congenital vascular malformation of the retinal characterized by multiple telangiectatic vessels
- leakage of serous and lipoproteinaceous exudate from these vessels cause retinal detachment.

Front 48

Coat's disease(radiologic characteristics)

Back 48

- Increased density in part or all of the vitreous of the globe
- normal globe size and lack of calcification.
- can appear identical to persistent hyperplastic vitreous or retinopathy of prematurity.

Front 49

Scleritis - pathologic features

Back 49

Idiopathic scleral inflammation or associated with systemic disease

Front 50

Scleritis(CT/MRI)

Back 50

Thickened, enhancing sclera is seen on enhanced CT or MR
-Choroidal detachment may be associated

Front 51

What is the most common tumor of the globe during childhood?

Back 51

Retinoblastoma

Front 52

Retinoblastomas, what percentage is unilateral vs. bilateral

Back 52

75% unilateral
25% bilateral

Front 53

Why is CT the preferred method for evaluating leukocoria?

Back 53

Because of it's sensitivity to calcification
MRI is used when further delieation of the extraocular extent of the tumor is required.

Front 54

What does a CT scan show in retinoblastoma?

Back 54

An intraocular mass with calcification in patient younger than three

Front 55

What if you see bilateral retinoblastoma and a pinealoma, what is it called?

Back 55

Trilateral retinoblastoma.

Front 56

What is the most common primary intraocular malignancy in adults?

Back 56

Uveal melanoma.

Front 57

Is CT/MR routhinely used in uveal melanoma dx?

Back 57

no, clinical-ultrasound diagnosis is made confidently.

Front 58

CT features of uveal melanoma

Back 58

ST mass adjacent to the outer layer of the globe that bulges inward toward the vitreous

Front 59

MR freatures of uveal melanoma

Back 59

Sharply circumscribed lesion with high signal on T1 weighted images d/t paramagnetic properties of melanin

Front 60

What are the most common lesions that metastasize to the globe?

Back 60

Lung
Breast

Front 61

Where does metastatic tumor to the globe most commonly involve?

Back 61

The uveal tract(ie. vascular layer between the retina and sclera)

Front 62

Ocular mets - CT characteristics

Back 62

Thickened areas o increased density
- usally in the posterior temporal portion of the uveal tract near the macula(an area of rich vascular supply)

Front 63

Choroidal hemangioma is associated with what syndrome?

Back 63

Sturge Weber syndrome

Front 64

Choroidal hemangioma - CT pathologic/radiographic features

Back 64

-Benign vascular lesion that can mimic more ominous intraocular masses
- on CT its a lenticular to flat, intensely enhancing ocular wall mass.

Front 65

Why is a CT/mri order in patient with a hypoplastic optic nerve?

Back 65

To exclude the possibility of an intraorbital or intracranial lesion affecting the visual pathway.

Front 66

Major Differential diagnostic considerations in a child with leukocoria?

Back 66

Toxocara endopthalmitis
Persistent hyperplastic vitreous
Retinopathy of prematurity
Coat's
(calcs are rare in these diseases, unlike retinoblastoma)

Front 67

Septo-optic dysplasia syndrome features?

Back 67

Bilateral or unulateral optic nerve hypoplasia
Absence of septum pellucidum
Dysplastic 3rd ventricle
Hypothalamic hypituitarism
Growth hormone deficiency.

Front 68

Causes of optic neuritis?

Back 68

MS
pseudotumor
Sarcoidosis
XRT
Viral
Tuberculous
Syphilitic neuritis

Front 69

What are the two common tumors of the optic nerve/sheath complex?

Back 69

Optic nerve glioma
Optic nerve/sheath meningioma

Front 70

Who usually presents with optic gliomas?

Back 70

- Children within their first 10 years of life
- could also have hypthalamic disorder and obstructive hydrocephalus(signals the presence of a larger tumor with intracranial extension)

Front 71

Optic nerve gliomas associated with what syndrome?

Back 71

NF I (1/3 of patients have NF1)
Conversely(15% of NF patients have optic nerve glioma)

Front 72

Intracranial extension of an optic glioma, compare and contrast from an optic nerve sheath meningioma.

Back 72

an optic nerve glioma extension intracranially along the optic pathyway
- optic nerve meningioma, if intracranial extension occurs, it extends only a short distance along the prechiasmatic optc nerve sheath

Front 73

Calcifications - optic nerve gliomas vs optic nerve meningiomas

Back 73

Optic nerve gliomas - non calcified
Optic nerve meningiomas - Have calcifications

Front 74

Optic nerve sheath meningioma
(clinical presentation)

Back 74

Middle aged women
Children with NF II

Front 75

Optic nerve glioma, high or low grade

Back 75

in childhood, optic nerve gloma is most commonly a low grade malignancy of the pilocytic astrocytoma variety.
in adulthood, its more aggressive like glioblastoma

Front 76

Optic nerve meningioma features?

Back 76

- Marked contrast enhancement
- Enhancing tumor around the nonenhancing nerve results in a "tram track" appearance on axial images

Front 77

What is the most common cause of an intraorbital mass lesion in adults?

Back 77

Pseudotumor

Front 78

Pseudotumor may be seen in association with?

Back 78

Wegener's granulomatosis
Fibrosising mediastinitis
Thyroiditis
Cholangitis

Front 79

Pseudotumor - biopsy of the involved orbital area reveals?

Back 79

- Lymphocytic infiltrate, may have a variable histologic appearance
- later in the disease fibrosis and collagen fibers appear in the pathologic specimen.

Front 80

Orbital pseudotumor involves which structures within the orbit?

Back 80

Retrobulbar fat(76%)
Extraocular muscle or muscles(57%
Optic nerve(38%)
Uveal-scleral area(33%)
Lacrimal gland(5%)

Front 81

What are the two principal pseudotumor types?

Back 81

Tumefactive(ie, diffuse involvement of conal and intraconal structures)
Myositic(involving the extraocular muscles)

Front 82

Tumefactive type of tumor must be differentiaed from what? How?

Back 82

True orbital tumor
Clinical presentation and response to steroids dictate the need for biopsy

Front 83

The myositic type of pseudotumor must be differentiated from?

Back 83

Thyroid Ophthalmopathy
-unilateral involvement of a single extraocular muscle including the tendinous insertions is highly suggestive)

Front 84

What is the most common cause of unilateral or bilateral exophthalmos in adults?

Back 84

Thyroid ophthalmopathy

Front 85

Thyroid ophthalmopathy versus myositic pseudotumor on CT?

Back 85

Thyroid opthalmopathy has EOM enlargement and spares the tendinous attachments to the globe
-Pseudotumor - enlarged EOMS and involves the tendinous attachements

Front 86

Carotid cavernous fistula - pathology

Back 86

Spontaneous or post-traumatic communication between the cavernous carotid artery and cavernous sinus

Front 87

Carotid cavernous fistular - radiology

Back 87

Engorgement of the superior ophthalmic vein and EOMs.

Front 88

Venous varix - pathologic features?

Back 88

An enormously dilated vein of either congestive or acquired orignin

Front 89

Venous varix - CT

Back 89

Lobulated densely enhancing intraconal structure that enlarges with valsalva
- may see phleboliths

Front 90

Superior ophthalmic vein thrombosis?
clinical presentation?

Back 90

- occurs in conjuction with cavernous sinus thrombosis
- Subsequent dysfunction of CN III, IV, and VI

Front 91

What is the most common orbital tumor?

Back 91

cavernous hemangioma

Front 92

Cavernous hemangioma on CT?

Back 92

Intraconal sharply circumscribed, rounded, dense mass that often spares the orbital apex
- uniform enhancement is the rule
- bone destruction never occures(but may cause bone deformity)

Front 93

At what age to cavernous hemangiomas present?

Back 93

20-40
unilateral proptosis with diplopia and diminution of vision resulting from optic nerve compression by tumor

Front 94

Who gets capillary hemangiomas?

Back 94

infant(<1 year) with proptosis and swelling of eyelid and conjunctive that increases with crying or Valsalva

Front 95

Most common causes of proptosis?

Back 95

Oribital pseudotumor
Cavernous hemangyioma
Oribital lymphoma(3rd most common cause)

Front 96

Technically speaking, the extraconal region is comprised of?

Back 96

only the lacrimal gland and fat.

Front 97

Most acute enlargement of the lacrimal gland is due to?

Back 97

inflammatory enlargement in younger patients resulting from postviral syndrome

Front 98

Chronic lacrimal gland inflammation is secondary to(3)?

Back 98

Sjogren's Syndrome
Mikulicz's syndrome
Sarcoidosis

Front 99

What is Mikulicz's syndrome?

Back 99

Nonspecific enlargement of the lacrimal and salivary glands associated with sarcoidosis, lymphoma, or leukemia

Front 100

What two epithelial tumors account for 50% of all lacrimal gland tumors?

Back 100

Benitgn mixed ttumor
Adenoid cystic carcinoma

Front 101

Whewre is non-hodgkin lympihoma of the orit most frequently found?

Back 101

in the lacrimal gland

Front 102

What is the most commmon meningioma in the extraconal area?

Back 102

Spenoid wing meningioma.