Ординатура / Офтальмология / Английские материалы / Orbital Tumors Diagnosis and Treatment_Karcioglu_2005

Diseases of the orbit present with typical localizing findings including proptosis, lid findings (e.g., edema, retraction, ptosis), visual loss

(e.g., optic neuropathy), external signs (e.g., palpable mass), or ophthalmoplegia. The clinician dealing with orbital disease should be aware, however, that neuroophthalmic disease can coexist with orbital disorders, that orbital findings may be the presenting signs of systemic or neurological conditions, and that certain key portions of the neuro-ophthalmic exam should be performed in selected cases of orbital disease. This chapter discusses the major neuro-ophthalmologic features of orbital disease and the common neuroophthalmic pathology of the orbit that may mimic tumors. The orbital tumors are not discussed in detail; instead a review of the tumors of the optic nerve with special emphasis on optic nerve glioma and meningioma is included.

HISTORY

The history is critical in the evaluation of patients with orbital disease and should include the typical assessment of any patient-related risk factors (age, gender, race, past medical history, surgical history, medications, allergies, social and occupational history). The history of present illness should include the tempo, duration, timing, severity, frequency, and quality of the ocular complaint. Associated signs or symptoms, palliating and precipitating factors, and current treatments should be recorded.

Age

The age of the patient may be helpful in the differential diagnosis of orbital disease. Most orbital lesions of childhood are benign (e.g., dermoid, epidermoid, capillary hemangioma, lymphangioma, optic nerve glioma). The most common malignant orbital lesion of childhood is rhabdomyosarcoma, which should be considered in every case of acute proptosis in a child. Leukemic infiltration, metastatic neuroblastoma, or Ewing’s sarcoma may also occur in the orbit of chil-

dren. Conversely, orbital cellulitis is common in children but less common in adults. Thyroid ophthalmopathy and orbital pseudotumor (idiopathic orbital inflammation) may present with findings that can mimic orbital neoplasms. These two conditions are common in adults but less common in children. In addition, younger children with orbital lesions should be evaluated and treated for amblyopia.

Past Medical History

The past medical history should include any prior ocular or sinus disease (e.g., mucocele, malignancy, infection) systemic medical problems (e.g., thyroid disease, diabetes, tuberculosis, sarcoid), prior radiation therapy (e.g., radiation necrosis or secondary neoplasms), immunosuppressive history (e.g., risk for secondary infections or neoplasms), or previous malignancy. Social history (e.g., smoking, alcohol, occupational exposure), family history (e.g., neurofibromatosis), past surgical history (e.g., orbital or sinus surgery), medications (e.g., steroids, antibiotics), and allergies may provide important information in the evaluation of the orbital process.

Time Course of Orbital Process

In general, an acute onset (e.g., hours to days) or a rapidly progressive course suggests infectious or inflammatory disease in the orbit. In the setting of trauma, an orbital retrobulbar hemorrhage or carotid cavernous fistula may produce rapid orbital findings within hours. On the other hand, neoplastic disorders typically produce a painless and progressive course (e.g., proptosis, visual loss, ophthalmoplegia). Some neoplastic disorders may present relatively acutely, however, including metastatic lesions, rhabdomyosarcoma, adenoid cystic carcinoma, and paranasal sinus with orbital extension. Other tumors may masquerade as inflammatory disease by producing rapid inflammatory signs.

Patients with orbital lesions may complain of transient monocular visual loss precipitated by gaze position (gaze-evoked amaurosis). The optic nerve, the oc-

ular blood supply, or the globe itself may be distorted by an underlying mass lesion (e.g., orbital tumor, orbital pseudotumor, thyroid ophthalmopathy) in certain fields of gaze.1

Symptoms

Patients with orbital disease may complain of diplopia, visual loss, ptosis, lid retraction, pain, proptosis, or visual loss. A careful history is required to document the onset, course, and progression of these symptoms. Any history of trauma should be noted.

EXAMINATION

The assessment of the patient should include a general workup as well as a complete ocular examination. Table 7.1 lists the major signs in the ocular examination of importance in orbital disease.

General Physical Examination

Patients with systemic thyroid disease may have a goiter. Orbital lesions (e.g., lymphoma or metastatic disease) may be associated with lymphadenopathy. Skin rash may suggest inflammatory etiology (e.g., systemic lupus erythematosus, sarcoid).

External Examination

The external examination of the ocular adenexa and eyelids can provide important information about underlying neuro-ophthalmic or systemic disorders. Lacrimal gland enlargement may be seen in sarcoidosis or underlying malignancy. Lid erythema or edema should be noted. Significant lid swelling, infiltration, or superior orbital mass can produce mechanical ptosis. Any deformity in the eyelid configuration (e.g., S-shaped eyelid in plexiform neurofibroma) should be documented. The lid position should be recorded and any lid retraction (e.g., thyroid ophthalmopathy) or lid lag (lid retraction in downgaze) should be noted specifically.

Palpation for any underlying mass, lymphadenopathy, or point tenderness may be helpful. Auscultation for orbital or cranial areas might reveal a bruit [e.g., ca-

TABLE 7.2. Etiologies for Enlargement of Extraocular Muscles.

rotid cavernous fistula, arteriovenous malformation (AVM)]. The globe position should also be noted (e.g., hypoglobus). The presence of enophthalmos (e.g., orbital floor fracture, metastatic scirrhous breast cancer) should also be recorded.2 Testing of trigeminal function including corneal sensation may help localize an orbital process with cavernous sinus extension.3,4 Orbicularis weakness may be seen in patients with seventh nerve weakness or myasthenia gravis.

Proptosis or enophthalmos can be assessed in the primary position or from a “worm’s-eye” view, with the examiner looking up at the patient. Formal measurement of proptosis (e.g., by Hertel exophthalmometer) is important in documenting exophthalmos and following progression or regression of this sign. Although thyroid ophthalmopathy is the most common cause of adult proptosis, other etiologies including neoplasms should be considered. In addition, patients with thyroid eye disease may also have an underlying orbital or intracranial tumor. Thyroid ophthalmopathy usually produces symmetric proptosis, lid retraction, and lid lag. Asymmetric proptosis (e.g., greater than 4–5 mm difference between eyes), ptosis rather than lid retraction, severe pain, or pupil involvement should suggest alternative etiologies for the proptosis.5,6 Other entities may produce proptosis and extraocular muscle enlargement; these are listed in Table 7.2.7–19

TABLE 7.1. Signs and Symptoms of Orbital Disease.

The anterior segment exam may show conjunctival chemosis or injection in thyroid disease or orbital inflammatory disease. Arterialization of the conjunctival vessels might suggest an underlying carotid cavernous fistula. Orbital AVMs may present with findings similar to cavernous sinus AVMs and may require superselective angiography for diagnosis. Anterior uveitis can be seen in patients with systemic inflammatory disorders including sarcoid.14–18

Measurement of Intraocular Pressure

Elevated intraocular pressure may occur in thyroid ophthalmopathy and carotid cavernous fistula. Increased pulse pressure (e.g., pulsatile mires on applanation) may suggest an underlying carotid cavernous fistula. Orbital tumors or hemorrhage may produce elevated intraocular pressure from increased intraorbital pressure.

Testing Afferent Visual Function

Testing of the afferent system, including visual acuity, visual field (e.g., automated perimetry, Goldmann perimetry), and color vision testing (e.g., Ishihara color plates), should be performed on any patient suspected of having an orbital process that is causing an optic neuropathy. Changes in refractive error (e.g., induced hyperopia) may occur from orbital lesions compressing the posterior globe. Orbital lesions may produce severe proptosis with secondary exposure keratopathy that may diminish the visual acuity.

Subjective tests comparing the afferent responses in each eye can provide additional evidence for an optic neuropathy. A red test object (e.g., a red top bottle) can be used to subjectively compare color saturation between hemifields in one eye or between the two eyes. Subjective desaturation of the color suggests an optic neuropathy. The subjective comparison of the brightness of light between eyes can also suggest an underlying optic nerve disturbance. The patient is asked to quantify or compare the brightness of a handlight shone in one and then the fellow eye. The difference can be quantified between the eyes. The clinician arbitrarily assigns the brightness of the better eye as 100% and asks the patient to rate by relative percentage the brightness of the involved eye. Contrast sensitivity tests using various spatial frequencies and contrast levels can also detect small or subtle differences in afferent function. These tests are highly sensitive but not as specific as the others just described.

Visual Field Testing

Visual field testing can help to localize a lesion affecting the anterior visual pathway. Optic nerve related defects may be central, cecocentral, arcuate, or altitudinal (Figure 7.1). Most lesions causing an optic neuropathy in the orbit will produce ipsilateral visual field loss consistent with optic nerve related field loss. Some orbital lesions, however, involve the intracranial optic nerve and chiasm, and combination visual field defects may occur. Lesions that involve the anterior chiasm may cause optic nerve related field loss in one eye and temporal field loss in the fellow eye from compression of the junction of the optic nerve

FIGURE 7.1. Goldmann visual field of the right eye shows a central scotoma and inferior arcuate visual field loss due to an optic neuropathy.

and chiasm. Lesions of the body of the optic chiasm produce a bitemporal hemianopsia. Lesions of the optic tract and other retrochiasmal diseases produce a contralateral homonymous hemianopsia.

Confrontation visual testing can easily be performed in the clinic. The clinician sits facing the patient and tests each eye separately, using his or her own eye as a control. The field can be tested with static or kinetic targets of various sizes or with the examiner’s fingers or hand as the target. Formal visual field testing provides more information than confrontation field testing. Kinetic manual perimetry (e.g., Goldmann perimetry) offers the ability to vary the test object size and brightness and the ability to test the peripheral visual field; another advantage is that the technician can monitor the testing. Goldmann perimetry also provides excellent information about the shape of visual field defects. The disadvantages of Goldmann perimetry are that the test is timeconsuming, requires a trained technician, and is not universally available. Automated computed perimetry (e.g., Humphrey visual field) has the advantage of reproducibility, and the depth of field loss can be quantified in decibels. The disadvantages of automated perimetry are the need for a reliable patient, who is able to follow instructions and pay attention to the testing stimuli. Elderly, very young, inattentive, or acutely ill patients may perform better on the Goldmann perimetry than automated testing. The Humphrey automated perimetry strategies can test the central 10 (e.g., 10-2 strategy), 24, 30, or 60 degrees. Patients with poor visual acuity (e.g., 20/200 or worse) may not be able to perform automated perimetry using the default stimulus size (e.g., Goldmann III test object size in Humphrey perimetry). The size of the stimulus can be increased (i.e., to Goldmann V) to improve reliability in patients with impaired central acuity.

Pupil Testing

Testing the pupillary light and near reaction is important in the assessment of afferent and efferent pupillary problems. Patients with visual loss should undergo careful assessment for a relative afferent pupillary defect because orbital lesions may produce an optic neuropathy. Patients with bilateral and symmetric visual loss may not exhibit a relative afferent pupillary defect. The absence of a relative afferent pupillary defect in a patient with a unilateral orbital lesion is strong evidence against an optic neuropathy.

Anisocoria may result from damage to the efferent sympathetic or parasympathetic pupil pathway. The oculosympathetic pathway is a three-neuron arc that begins in the hypothalamus, descends in the brain stem to the spinal cord (C8-T2 level), then arches over the apex of the lung, up the cervical sympathetic chain, and enters the cranial cavity with the internal carotid artery. The third-order neuron travels on the carotid artery into the cavernous sinus and enters the orbit through the superior orbital fissure. This third order neuron of the sympathetic pathway may be affected by orbital disease (postganglionic Horner syndrome). The ciliary ganglion resides within the posterior orbit between the optic nerve and the lateral rectus muscle. A tonic pupil may result from damage to the ciliary ganglion (including orbital surgery) or from orbital lesions.

Ocular Motility Measurements

Patients with orbital disease may present with diplopia and ophthalmoplegia. The ocular motility may be impaired by restrictive disease (e.g., orbital floor fracture, mucocele, orbital tumor) or paretic disease. Figure 7.2 shows a patient with an elevation deficit and ptosis due to a frontal sinus mucocele. A rapid saccade that abruptly terminates (“hits the wall”) suggests restrictive disease, whereas a slowed saccade suggests paretic disease. Forced duction and forced generation testing may be positive in restrictive etiologies.

Ophthalmoscopy

Compressive optic neuropathy may occur in patients with orbital disease. The typical features of an optic neuropathy may be present, including visual acuity loss, visual field loss, and a relative afferent pupillary defect. The optic disk in these cases may be normal (i.e., retrobulbar optic neuropathy), swollen, or pale (Figure 7.3). In most cases, if the compressive lesion is producing optic disk edema, it will be located more anteriorly in the eye, orbit, or the optic canal. Intracranial lesions are less likely to produce compressive optic disk edema, although if large enough may

O F O R B I T A L T U M O R S

A

B

FIGURE 7.2. Ocular motility photos show an elevation deficit and ptosis (A) due to a frontal sinus mucocoele (B).

produce papilledema (disk edema due to increased intracranial pressure). Optic disk edema that is longstanding may compress the central retinal venous circulation, and collaterals between the retinal and choroidal circulations may form to bypass this obstruction. These new blood vessels are referred to as optociliary shunt vessels (although technically they are collateral vessels and not shunts). Optic nerve collaterals in the setting of compressive optic neuropathy (e.g., progressive visual loss and optic atrophy) are a sign of orbital tumor, usually optic nerve sheath meningioma, or, less likely, optic nerve glioma.

Retinal Findings

Orbital disease may produce retinal and retinal vasculature changes in the fundus.4 Venous engorgement and tortuousity may be seen in carotid cavernous fistulas or less commonly in compressive orbital disorders. Secondary retinal vein occlusion with intraretinal hemorrhages and macular edema may be seen. Choroidal folds may result from orbital lesions compressing the globe. Fluorescein angiography might demonstrate the folds more dramatically (Figure 7.4).

A

B

C

FIGURE 7.3. Optic disk photographs show (A) mild optic nerve swelling, (B) more severe optic disk edema, and (C) optic atrophy.

The evaluation of orbital lesions should include orbital imaging [e.g., orbital ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI)].

Retinal artery occlusions may result from orbital infections (e.g., angioinvasive aspergillosis or mucormycosis) or in acute orbital trauma (e.g., retroorbital hemorrhage with elevated intraorbital and intraocular pressure). Intraocular inflammation (e.g., exudative retinal detachment, vitreous cells, retinal in-

filtrates, retinal vasculitis, optic disk edema) may occur in patients with intraorbital inflammatory (e.g., scleritis, systemic lupus erythematosus, Wegener’s granulomatosis), infectious (e.g., endophthalmitis with extrascleral extension), or neoplastic (e.g., orbital lymphoma) conditions.

ORBITAL IMAGING

In general, MR is superior to CT scanning for demonstrating intracranial involvement of orbital lesions.

FIGURE 7.4. Optic disk photographs (A) show optic disk edema and choroidal folds that are seen better on the fluorescein angiogram (B) as alternating light (hyperfluorescent) and dark (hypofluorescent) lines. (C) Sagittal T1-weighted MR imaging shows an orbital mass compressing the posterior globe.

CT scans show bony anatomy (e.g., hyperostosis, bone destruction, bone remodeling) and calcifications better than MR scans (Figure 7.5). Fat on T1-weighted MR studies is hyperintense. Gadolinium contrast is also hyperintense on T1-weighted images. Fat suppression is necessary for orbital studies in order to visualize any pathologic enhancement. Thus, MR studies of the orbit should be performed with fat suppression techniques and gadolinium contrast material (Figure 7.6). In addition, specific signal characteristics on MRI may help in distinguishing certain tumor types (Figure 7.7).

SYSTEMIC DISORDERS THAT

MAY AFFECT THE ORBIT

Although the focus of this chapter is on orbital tumors and neuro-ophthalmology, the clinician should be aware that other conditions can mimic an orbital tumor. Complete evaluation (including imaging and medical consultation) for these underlying disorders may be necessary.

Sarcoidosis

Sarcoidosis is a multisystem, granulomatous disorder of uncertain etiology. Sarcoid has a predilection for the lungs (e.g., hilar adenopathy) and may produce anterior or posterior uveitis (e.g., choroiditis, retinal vascular disease, optic neuritis, optic nerve granuloma). Although lacrimal gland and extraocular muscle involvement may occur in sarcoid, orbital involvement

is uncommon.14,15 Neurologic manifestations include optic neuropathy, papilledema, intracranial granuloma, vasculitis, and meningitis.16–18

Wegener’s Granulomatosis

Wegener’s granulomatosis is a systemic inflammatory disorder characterized by necrotizing granulomatous vasculitis of the upper and lower respiratory tract and kidney involvement. The orbit may be involved in 20 to 40% of cases including conjunctivitis, episcleritis, scleritis, keratitis, uveitis, optic neuropathy, and orbital extension (e.g., proptosis, chemosis, ophthalmoplegia) of sinus disease. Neurologic manifestations include peripheral and cranial neuropathy, seizure, cerebritis, and focal neurologic deficit.10

Polyarteritis Nodosa

Polyarteritis nodosa is a multisystem small to medium-sized vessel vasculitis that may affect the heart, kidney, liver, and gastrointestinal tract. Orbital inflammatory disease is an uncommon finding, but choroidal and retinal ischemia related to vasculitis may occur.

Giant Cell Arteritis

Giant cell arteritis is a vasculitis of the elderly that typically presents with headache, scalp tenderness, jaw claudication, and visual loss. Orbital involvement is rare but may mimic orbital inflammatory pseudotumor.15

FIGURE 7.5. Axial CT scan with bone windows shows right sinus lesion with orbital extension due to renal cell carcinoma metastasis.

ORBITAL EXTENSION OF

INTRACRANIAL DISEASE

Intracranial tumors may rarely extend into the orbit. Table 7.3 lists several systemic or intracranial processes that may involve the orbit from direct exten- sion.11–90 Orbital extension may produce ophthalmoplegia, optic neuropathy, and proptosis. Appropriate head and orbital imaging may be needed in these circumstances.

The two most commonly encountered tumors of the optic nerve that involve the orbit are optic nerve glioma and optic nerve meningioma.

Optic Pathway Glioma

Optic nerve glioma is a tumor of childhood,20–34 and presentation in adulthood might suggest a more malignant glioma.21 Although the tumor can present at any age, most patients are less than 10 years old with a mean age of 8.8 years. There is no gender predilec-

FIGURE 7.6. (A) Axial non-fat-suppressed MR images show the hyperintense fat on T1-weighted imaging (B). Axial and (C) coronal MR studies show fat-suppressed postcontrast T1-weighted images.

Note the previously hyperintense fat signal on these T1-weighted images. (D) Metastatic lesion to the right superior rectus muscle.

tion.34 Optic pathway gliomas are associated with neurofibromatosis type 1 (NF1) (see Chapter 17); the tumor may be asymptomatic in these patients, or appear later in life after initially normal imaging.22,24,25 Some studies have suggested that patients with NF1 may have borderline favorable prognosis, but other studies have shown little or no difference prognosis.26,29,31,33,35

Any part of the optic pathway may be involved with a glioma, and prognosis depends in part upon the extent and location of the tumor. One or both optic nerves alone are involved in 24%, the optic disk is involved in 1.6%, and the optic chiasm or tract is involved in 75%. In general, the more anterior the lesion, the better the prognosis.

Optic pathway gliomas involving the orbit produce proptosis, ophthalmoplegia, and painless progressive visual loss.32 Visual loss is present at presentation in

87.5%. Hypothalamic symptoms (26%) or endocrinologic manifestations (e.g., diabetes insipidus, diencephalic wasting, precocious puberty, somnolence, growth failure) may occur in chiasmal-hypothalamic tumors.36 Optic disc swelling (35%) or atrophy (59%) is generally present, and rarely optociliary shunt vessels may occur.23

Neuroimaging with an MR scan with gadolinium is superior to CT scan for demonstrating intracranial extension. The imaging typically shows intrinsic enlargement of the optic nerve with variable contrast enhancement.30,37 Figure 7.8 shows a left optic nerve glioma on an axial fat suppressed MR of the orbit. The treatment of optic pathway gliomas is controversial.38 Most authors recommend a period of observation for progression prior to initiation of therapy as gliomas are often static lesions (after an initial but variable pe-

A

B

FIGURE 7.7. T2-weighted MR image of the orbit shows a markedly hypointense lesion (A) consistent with a hypercellular fibrous tumor, in this case solitary fibrous tumor of the right orbit (B).

riod of growth). Radiation therapy is generally reserved for patients over age 5 years with progressive radiographic findings or worsening clinical signs and symptoms.32 The risks of radiation are considerable and include cerebrovascular disease, moya moya disease, cerebral atrophy, subnormal intelligence or learning disabilities, secondary malignancies (e.g., astrocytomas), cataracts, radiation retinopathy or optic neuropathy, endocrinopathy, and hypothalmic dysfunc- tion.39–41 These risks are generally higher the younger the age of the patient. Chemotherapy is emerging as a possibly safer alternative to radiation therapy particularly in younger children.32 Various agents and combinations of agents have been used with some anecdotal success including: actinomycin D, vincristine, CCNV, 6-thioguanine, procarbazine, dibromodulatol, topotecan, carboplatin, and etoposide.32

TABLE 7.3. Systemic or Intracranial Lesions That May Extend into the Orbit.

FIGURE 7.8. Axial fat-suppressed T1-weighted postcontrast MR scan of the orbit shows a left fusiform enhancing optic nerve mass consistent with an optic nerve glioma.

Surgical therapy is generally limited. A strictly optic nerve glioma with no useful vision or progression may be resected. Chiasmal, hypothalamic, or optic tract gliomas, cannot be completely resected because of unacceptable visual and surgical morbidity. Any exophytic and symptomatic component of these tumors, however, may be debulked. Secondary hydrocephalus may require shunting procedure.32

The prognosis of optic pathway gliomas is quite variable and is in part based upon location.42 Most (80%) have stable vision after an initial period of visual loss. The 10-year overall survival rate is between 85% to 100% in various series, and spontaneous regression may occur.27,28

Adult Malignant Glioma

As opposed to optic pathway gliomas in childhood, gliomas in adults tend to be more malignant. The patients tend to be older males. The clinical signs and symptoms include rapidly progressive loss of vision unilaterally or bilaterally. The visual acuity usually progresses to complete blindness over an average of 11 weeks. Optic nerve related visual field defects occur. The optic disk may be normal or show swelling or atrophy. Proptosis or ophthalmoplegia may occur if the lesion involves the orbital optic nerve. Retroorbital pain is quite common. Macular edema, a cherry-red spot, and flame hemorrhages or hemorrhagic papillopathy may occur and simulate a central retinal vein occlusion. Unlike childhood optic gliomas, adult malignant gliomas are not associated with NF-1. The treatment options are limited and include radiation therapy or chemotherapy. The pathology is consistent with a malignant astrocytoma. The prognosis is generally poor with an overall mortality of 97% and a mean survival of 8.7 months (range 3 to 24 months).21,34

Meningiomas

Meningiomas may occur primarily in the optic nerve sheath or extend into the orbit secondarily from the intracranial cavity.43–58 Meningiomas typically affect middle-aged patients. There is a female to male ratio of 3 to 1, and Caucasians are more affected than African-American patients.43,44 There is an increased frequency of meningioma in neurofibromatosis I and II, and multiple meningiomas (e.g., bilateral optic nerve sheath meningiomas in NF-2) may occur in these patients.45 The symptoms of a meningioma affecting the anterior visual pathway include painless and gradually progressive loss of vision or visual field. Frontal or olfactory meningiomas may have mental status changes. There may be diplopia from extraocular muscle, orbital, or cavernous sinus involvement. The signs of anterior visual pathway meningioma in-

clude loss of visual acuity and field and an ipsilateral RAPD. There may be optic disk edema, optic atrophy, or the disk may be normal (retrobulbar optic neuropathy). Optociliary collateral (“shunt”) vessels may be present on the optic nerve head.55

Neuroimaging typically shows characteristic but not necessarily diagnostic features of meningioma.58 Some patients may have meningocoele that might mimic a sheath meningioma.47 MR imaging is superior to computed tomography (CT) scans in the evaluation of meningioma, but a CT scan may show hyperostosis of adjacent bone or calcification within the lesion. Magnetic resonance imaging typically shows an isointense lesion on T1-weighted images with homogenous gadolinium enhancement. There may or may not be a classic but not pathognomonic dural tail of enhancement. Optic nerve sheath meningiomas have a more diagnostic radiographic appearance and may display a classic “tram track” appearance of enhancement of the optic nerve sheath.

The management of symptomatic intracranial meningiomas must be individualized. The tumor is usually histopathologically benign but may compress vital structures. A gross total resection is generally attempted if the patient is a good surgical candidate, is symptomatic with good expectation for improvement with decompression, and if the surgery is technically feasible. If the meningioma is encasing or surrounding vital structures (e.g. cavernous sinus, internal carotid artery), a subtotal excision may have to be performed. Sequential neuro-ophthalmic evaluations and neuroimaging studies are recommended to detect postoperative recurrence or progression. Postoperative radiation may be employed for malignant or aggressive pathology or for residual, recurrent, or non-re- sectable tumors if signs or symptoms progress.48–52,56

Optic Nerve Sheath Meningiomas

Optic nerve sheath meningiomas usually do not require biopsy for diagnosis if the typical clinical and radiographic features are present.53,58 Figure 7.9 shows a typical sheath meningioma on T1-weighted postcontrast fat suppressed MR scan of the orbit. Observation for progression is a reasonable first step in management. Complete surgical excision usually produces irreversible visual loss and is generally reserved for eyes without visual potential and vision-threatening or cosmetically unacceptable proptosis. Observation is an acceptable protocol to evaluate progression with serial neuroimaging (e.g., MRI head and orbits with gadolinium and fat suppression) every 6 months for 2 years, then yearly if there is no growth. Most authors would consider radiation therapy to be the treatment of choice for optic nerve sheath meningioma if preservation of visual function is the goal.48 Improved techniques of delivery of radiotherapy (e.g., conformal,

FIGURE 7.9. Axial fat-suppressed T1-weighted postgadolinium MR scan of the orbit shows a left enhancing optic nerve sheath meningioma.

three dimensional, intensity-modulated, radiotherapy) may decrease the risks of radiation side effects.52,54

CONCLUSIONS

Orbital disorders may present with neuro-ophthalmo- logic findings (e.g., optic neuropathy). In addition, neurologic and systemic diseases may present in the orbit. The clinician should understand the neuroophthalmic considerations in orbital disease and perform appropriate evaluation and imaging.

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