Orbit

Orbit Chapter 13

ophthalmic artery and optic nerve passes though optical canal with in annulus of Zinn

Anatomy • •

pyramid of 4 walls covering posteriorly each orbit has a lateral and medial wall forming 45 C angle which result in a right angle between two lateral walls

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pear shape, with ON as stem

Blood supply ophthalmic artery -principal arterial supply - first mahor branch of internal carotid arter -passes beneath optic nerve branches: 1.

central retinal artery -First intraorbital branch - enters ON about 9-15 mm behind the globe

30 mL= normal volume of adult orbit 1/5= occupied by eyeball 4/5= fat and muscle

2.

lacrimal artery supplies lacrimal gland and upper eyelid, muscular branch to muscles in orbit

Orbital septum anterior limit of the orbital cavity barrier between eyelids and orbit

3.

long posterior ciliary artery - supplies ciliary body and anastomoses with anterior ciliary artery forming major arterial circle of the iris

4.

short posterior ciliary artery supplies choroids and parts of optic nerve

anterior circumference -smaller in diameter than the inside rim - has a sturdy protective margin

Orbital floor - thin, easily damaged by direct trauma to globe resulting in “blowout” fracture Lamina papyracea = paper thin medial wall commonly Eroded in infections with in sphenoid And ehtmoid sinuses Nuerofirbromatosis = defect in roof of orbit resulting in Visible pulsations of globe orbital bones frontal zygomatic palatine lacrimal

sphenoid maxilla ehtmoid

anterior ciliary artery -supplies: anterior sclera episclera limbus conjunctiva VENOUS DRAINAGE superior and inferior ophthalmic veins main venous drainage drains vortex veins, anterior ciliary veins, central retinal vein

roof: orbital plate of frontal bone lesser wing of sphenoid bone

superior orbital vein comes from superior and supratrochlear veins and branches of angular vein driains skin of perorbital region

lateral wall: greater wing of sphenoid zygomatic /malar bone(srtongest )

cavernous sinus -direct communication to the skin

floor: orbital plate Maxilla Zygomatic bone orbital process of Palatine

physiology of symptoms

medial wall: angular process of Frontal bone Ethmoid Lacrimal body of Sphenoid orbital apex portal of entry of all nerves and vessels site of origin of all EOM except INFERIOR OBLIQUE Superior Orbital Fissure -Located between body and greater/lesser wings Of sphenoid lateral part of SO fissure/ outside the annulus The ff structures passes: Superior ophthalmic vein Lacrimal, Frontal and Trochlear nerve -

medial part/ with in the annulus the ff structure passes: Superior/ Inferior division of ON Abducens Nasocillary nerve

inferior ophthalmic vein -passes at any part of fissure

proptosis= forward displacement of eyeball due to inc orbital contents = hallmark of orbital disease = not injurious unless lids are unable to cover the cornea psuedoproptosis = apparent proptosis in absence of orbital disease axial proptosis= straight displacement of the globe nonaxial proptosis= sideways or vertical displacement of globe pulsating proptosis= reflects pulse on orbital vascular malformation or transmission of cerebral pulsations in absence of superior orbital roof = seen in type 1 nuerofibromatosis positional proptosis= changes with valsalva’s maneuver = sign of orbital varices or mengingocele intermittent proptosis= result of sinus mucocele * hertel exopthalmometer standard method of quantifying magnitude of proptosis. >2 mm abnormal

* change in the position of eyeball causes dissociation of ocular movements and diplopia * Pain results form rapid expansion, inflammation or infiltration of sensory nerve

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* vision not affected unless lesion arises form optic nerve *involvement of superior orbital fissure by trauma or tumor produces diplopia from disturbances of function of occulomotor, trochlear, abducens nerves and corneal and facial anesthesia known as orbital fissure syndrome *if lesions involve orbital apex then it results to orbital apex syndrome diagnostic studies imaging CT = single most important diagnostic study in investigation of orbital disease MRI= displays subtle changes within soft tissue that can’t be imaged with CT =less useful for bony changes UTZ= noninvasive and inexpensive, limited to anterior portion of the orbit Venography= defines the extent of orbital venous disease Angiography= used in diagnosis of certain orbital vascular disease Radiography= useful in fractures Fine- needle aspiration= invasive procedure, cytology specimens can be aspirated from a lesion, exact location of lesion determined by CT imaging. DISEASE AND DISORDERS OF ORTBIT INFLAMMATORY DISORDERS 1.

GRAVES OPHTHALMOLOGY Most common cause of unilateral or bilateral proptosis in adults or children AKA as Dysthyroid ophthalmology, dysthyroid eye disase Seen in hyperthyroid patients

Ophthalmic grave disease- term used when it occurs with hypothyroidism or with no detectable thyroid anomaly logophthalmos= proptosis and lid retraction clinical findings: - lid retraction only when associated with thyroid Disease - ocular myopathy with lymphocyitc infiltration and edema of the rectus muscle later on, inflamed muscle becomes fibrtotic and permanently restricted eye may be tethered so as to raise intraocular pressure when it is measured in upward gaze diplopia in upper field of gaze due to infiltrative myopathy involving inferior rectus EOM may become massively enlarged and may compress ON Compression of optic neuropathy -most common with enlarged posterior aspecdt oF muscles and occurs without sever proptosis - early signs afferent papillary defect, impairment color vision, loss of visual acuity treatment GOAL IS TO MAINTAIN CORNEAL PROTECTION  

address problems if diplopia, proptosis and compressive optic neuropathy manage thyroid status

oral corticosteroids (prednisone 60-100 mg/d) to control acute phase of infiltrative myopathy *limit use due to side effects orbital radiation effective during active phase of disease when there is soft tissue swelling, chemosis radiation therapy for early compression neuropathy, if unresponsive then surgical decompression surgery to reduced proptosis but there is a risk of intractable diplopia but lesser risk of infection 

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2.

PSUEDOTUMOR - non neoplastic process that produces the sentinel sign of an orbital neoplasm -

inflammatory psuedotumor is frequent case of proptosis in adults and children some associated with Wegener’s granulomatosis site of inflammation is diffuse, not amendable to excision. Can involve orbital structure or cell type Onset rapid, presence of pain Usually UNILATERAL When both orbits are involved, more often a manifestation of vasculitis

Differential dx: grave’s ophthalmopathy Orbital syndromes Treatment:  Systemic NSAIDs, corticosteroids, radiation

ORBITAL INFECTIONS 1. ORBITAL CELLULITIS -frequent cause of proptosis in CHILDREN -needs immediate treatment - Dx based on clinical findings -also occur among aged and immunocompromised -TRAUMA introduces contaminated material into the orbit through skin and paranasal sinuses - most cases arise from extension of sinusitis through ethmoid bones - organisms responsible: H. influenza S. pneumoniae Other strep and staph Clinical findings: *preseptal= most common presentation *CT and MRI distinguishes between preseptal and orbital infections * edema, erythema, hyperemia, pain, leukocytosis * deep involvement: chemosis, proptosis, limitation of eye movement, reduction of vision * extension to cavernous sinus: bilateral involvement of CN II-VI edema and septic fever * erosion of orbital bones lead to brain abcess and meningitis Treatment:  Emperic tx that covers H. influenzae and anaerobes while waiting for culture results  IV antibiotics once blood culture result is obtained  hot compress localize infection

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meninges are involved

Nasal decongestants and vasoconstrictors help drain paranasal sinuses Surgical drainage for suppurative preseptal cellulit

VASCULAR ABNORMALITIES

2. MUCORMYCOSIS -ZYgomycetes group that invades vessels and cause ischemic necrosis - common among diabetics and immunocompromised pts - infections begin on sinuses and erodes into the orbit cavity - patient ill looking with pain and proptosis -PE on nose and palate: necrotic area on mucosa - without TX, infection gradually erodes cranial cavity- meningitis, brain abcess and death Treatment:  

Surgical debridement AMphotericin B IV

* recurrence is common CYSTIC LESIONS 1. DERMOID -benign choristomas from embryonic tissue -arise form surface ectoderm and contains epithelial structures like keratin, hair, teeth -most are cystic and filled with oily fluid that causes severe inflammatory rxn when liberated in the orbit - most occur at SUPERIOR TEMPORAT QUADRANT of the orbit On X-ray: Sharp, round bony defects from pressure of Slowly growing mass to the periosteum.

1.

2.

CAROTID ARTERY- CAERNOUS SINUS FISTULA high-flow shunt low-flow shunts ( dura and carotid fistula) are easily diagnosed spontaneous and often misdiagnosed usually follows trauma Sings: severe congestion, chemosis, pulsating proptosis, loud bruit

2.

3.

SINUS MUCOCELE -proximity of orbit to paranasal sinus leads to invasion of bony walls and extension of obstructed sinus to the orbit - CT and MRI differentiates sinus mucocele form dermoid cyst and defines lesion - otolaryngologic and neurosurgical assistance necessary for removal MENINGOCELE -cystic mass filled with CSF due to erosion of menginges into the orbital cavity through congenital dehiscence in the bony structure -fluctuant mass increases with valsalva’s maneuver -most are present at birth

meningomyelocele- both brain and

Sings: mild congestion, venous engorgement, arterialization, elvated IOP, mild proptosis, faint bruit

Dx.: MRI and subtraction angiography Tx:  selective intra-arterial or transverse embolization

PRIMARY ORBITAL TUMORS 1.

EPIDERMOID CYST -superficial keratin filled mass near superior orbital rim -congenital or posttraumatic -treatment excision DERMOLIPOMA -solid mass of fatty material occurs below conjunctival surface -larger than they appear to be -excission may case damage to vital structures Tx:  limited excision

ARTERIOVENOUS MALFORMATION uncommon cause of proptosis varices produce intermittent proptosis with pain and transient reduction of vision proptosis induced by valsalva’s maneuver dx by MRI tx: surgery

CAPILLARY HEMANGIOMA common benign tumors that sometimes involves the eyelids and orbit SUPERFICIAL LESION= RED DEEP LESIONS= BLUISH 90% Apparent before 6 mos enlarges rapidly ‘til first year of life regress slowly over 6-7 years lesions within orbit causes STRABISMUS OR PROPTOSIS lesions within eyelids induces ASTIGMATISM OR OCCLUDE VISION (AMBYLOPIA)

Tx:  superficial lesions= none, regress spontaneously  in some cases, Intralesional sustained-release corticosteroids effective coz steroids have antiangiogenic effects  prolonged compression  systemic steroids  scleroising agents  cryotherapy  laser surgery  radiation  surgical resection 2.

CAVERNOUS HEMANGIOMA -benign, grows slowly, symptomatic in middle life - mostly occurs in WOMEN - most often lie within muscle cone causing AXIAL PROPTOSIS, HYPEROPIA, CHROIDAL FOLD -DO NOT REGRESS SPONTANEOUSLY

Tx:  3.

Surgery in symptomatic patients

LYMPHANGIOMA

-HISTOLOGICALLY Similar to hemangioma in early stages -begins in infancy though may also present later in life -INTERMITTENT HEMORRHAGE and GRADUAL WORSENING -tumor is multifocal and occurs in soft palate, other areas orbit and face - histologically: large serum-filled channels and lymphoid follicles goals of treatment: acute decompression of a hemorrhagic blood cyst eradication of tumor Tx:    4.

Needle aspiration of blood Extirpation of specific cyst Excision of tumor ( seldom satisfactory)

RHABDOMYOSARCOMA -MOST common primary malignant tumor of orbit in childhood -usually presents before 10 years old -rapid growth of tumor -tumor destroys adjacent orbital bone and spreads to brain

Tx: 

5.

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OPTIC NERVE GLIOMA 75% Of symptomatic patients occur before 10 years old 25-50% are associated with neurofibromatosis 1 most common sign: VISUAL LOSS AND OPTIC NUEROPATHY

TX:     

No compelling statistics to treat Other cases require excision radiotherapy (effective in stabilizing vision) chemotherapy ( decrease risk of secondary damage to CNS) lateral orbitotomy ( cosmetic purposes in pts with blind eyes with proptosis)

LACRIMAL GLAND TUMORS -50 % are epithelial tumors, one half are malignant -50% are inflammatory masses and lymphoproliferative tumors -most common: PLEOMORPHIC ADENOMA/BENIGN MIXED TUMOR poor prognosis

excision biopsy ( in malignant tumor with pain and destructive bone changes on xray) orbital exenteration with ostectomy

LYMOHOMA

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divided into MALIGNANT MONOCLONAL LYMPHOMAS AND REACTIVE LYMPHOID LYMPHOMAS immunologic and DNA hybridization differentiates the two MONOCLONAL POLYCLONAL PROLIFERATION PROLIFERATION - Malignant - benign - remain localized and -can have small clones of B behave in benign fashion lymphocytes - excellent prognosis -excellent prognosis - differetntial diagnosis: orbital infection psuedotumor w/ or w/out systemic vasculitis Tx: radiation ( if disease is confined within the orbit) HISTIOCYTOSIS 

Combination external megavoltage radiation and chemotherapy (90 % survival rate compared to orbital exenteration)

neurofibromatosis 1 (RECKLINGHAUSEN’S DISEASE) autosomal dominat trait in chromosome 17 Plexiform nuerofibromas are characteristic Can distort eyelids With café au lait spots---helps confirm Dx Often with defective sphenoid bone Lead to PULSATING EXOPHTHALMOS OR ENOPHTHALMOS Optic nerve gliomas produce proptosis and visual loss in 5 % of affected patients Some develop menngiomas and rarely, malignant peripheral nerve sheath tumors

propensity for recurrence and malignant transformation

Tx:

-proliferation of Langerhans cells with cystoplasmic granules the younger the child is diagnosed, greater chance of developing multifocal disease HAND-SCHULLER-CHRSITIAN DISEASE:  Multifocal lytic skull lesions  Proptosis  Diabetes insipidus

NUEROFIBROMA -

6.

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LETTERE-SIWE DISEASE:  Cutaneous, visceral and lymph node involvement

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Surgical curettement ( orbital lesions) Corticosteroid injection Low-dose radiation

Tx:

METASTATIC TUMOR -reach orbit by HEMATOGENOUS SPREAD coz orbit is devoid of lymphatics -usually metastasis form: breast Cancer in women lung Cancer in men - more common in choroid than in orbit - many respond to radiation and chemotherapy nueroblastoma =MOST COMMON METASTATIC TUMOR IN CHILDREN = good prognosis in children under 11 months SECONDARY TUMOR -

basal cell , squamous cell and sebaceous gland carcinomas that spread locally to orbit nasopharyngeal carcinomas most common form of maxially sinus meningiomas invade posterior orbit

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MYA SECB MED‘08