grave soph thal mop a thy

7/31/2019 Grave Soph Thal Mop a Thy

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Graves ophthalmopathyand

fat removal orbitaldecompression

Chen Su-Yu


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Introduction

Exophthalmos, or proptosis, occurs when there

is a discordant relationship between the soft

tissue and bone of the anterior orbit and the

globe. The adult orbit has a fixed volume of

approximately 30 ml. When the soft tissue

contents of the orbit exceed this amount,

exophthalmos occurs. As an example, anincrease in soft tissue volume of 5 ml (16%)

will result in 4-5 mm of proptosis


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Introduction

Graves disease represents the most common cause of bilateralexophthalmos. This condition is generally referred to asGraves orbitopathy (ophthalmopathy

Graves orbitopathy typically affects middle-aged women. It is

5 times more common in women than men. Peak incidenceoccurs in the 3rd and 4th decades of life. Severe exophthalmosis more common in elderly men. There is an increasedprevalence in smokers, and a genetic predisposition has beenestablished

Though associated with Graves Disease, exophthalmos is NOTnecessarily associated with hyperthyroidism. 20% of patients

with Graves orbitopathy are euthyroid.


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Pathogenesis

Graves orbitopathy likely arises from autoimmune,primarily T-cell, dysfunction resulting in lymphocyticinfiltration and immune complex deposition with resultantedema and proliferation of extraocular muscles, intraconaland extraconal fat, and the lacrimal gland.

There are both infiltrative and noninfiltrative ocularchanges in Graves.

Infiltrative changes involve mononuclear cells causingactivation and proliferation of fibroblasts resulting in the

production of collagen and glycosaminoglycans. The endresult is edema and fibrosis.

Noninfiltrative changes involve spastic retraction ofeyelids, an increase in palpebral fissure width, andsympathetic hypertonia


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Clinical Manifestation

Ultimately, thickening of the external ocular muscles, orbital fat herniation,

proptosis, retraction of both the upper and lower eyelids, descent of theeyelid-cheek complex, and divergence of gaze occur.

In addition, one may see eyelid edema, conjunctivitis, photophobia,chemosis, lagophthalmos, headache, gritty sensation in the eye, retrobulbarpain, and tearing.

Thickening of the superior rectus muscle can result in decreased venousflow via compression of the superior ophthalmic vein.

Hypertrophy of the extraocular muscles can result in ophthalmoplegia andthus diplopia, most frequently involving the inferior and medial rectus

muscles resulting in limitation of both upward and lateral gaze.

As inflammation of the orbital contents occurs, an increase in soft tissuevolume results in increased intraorbital pressure, which causes anteriordisplacement of the globe and stretch (and/or compression) of the opticnerve with the potential for optic neuropathy


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Clinical Manifestion

Optic neuropathy occurs in less than 5% of Gravesorbitopathy, but it is the most common cause ofvision loss in this setting; the progression is usuallyinsidious. This neuropathy usually occurs in patients

with proptosis, but can occur in patients withoutsignificant proptosis.

Except for cases of rapidly progressiveexophthalmos (malignant exophthalmos) the eyelids

are capable of closing sufficiently to protect thecornea. Thus, while approximately 50% of Gravespatients experience eye symptoms, onlyapproximately 5% of cases are severe enough to

warrant intervention.


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Patient evaluation

A complete ophthalmologic exam is necessary. Theamount of globe protrusion is measured using Hertelexophthalmometry.

Assessment of visual acuity, visual fields, and colorsaturation must be performed to exclude opticneuropathy.

Nasal endoscopy should be performed to diagnosisany sinonasal problems such as septal deviation orpolyposis. In addition, the thyroid gland should bepalpated.


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Patient Evaluation

Radiographic imaging is an important part of the evaluation.A CT or MRI of the orbit and sinuses represents the standardof care. This helps to rule out other pathologic conditions ofthe orbit, especially in a case of unilateral exophthalmos. In

addition, imaging will help to establish the presence orabsence of sinusitis, septal deviation, and hypoplasticmaxillary sinusesall of which will affect the approach totreatment.

MRI measurement of T2 relaxation time can be useful for

detecting external ocular muscle edema. Proptotic patientswith an increased mean T2 relaxation time are more likely torespond to anti-inflammatory therapy, while those without T2relaxation time prolongation are more likely to require orbital

decompression.


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Differential Diagnosis

Graves orbitopathy may be unilateral (10-20%) orbilateral (80-90%).

Pseudotumor cerebri represents the second mostcommon cause of bilateral exophthalmos. CT or

MRI shows generalized edema of the orbital softtissues and occasionally the brain.

Meningioma en plaque results in severe

exophthalmos with eyelid edema. Usually, the lowerlid is affected withoutlid retraction.

Axial myopia is a common cause of unilateralexophthalmos. This is diagnosed by retinoscopy and

A-scan ultrasound


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Differential Diagnosis

Inflammatory pseudotumor mimics a neoplasm withthe sudden onset of proptosis, lid edema, pain,ophthalmoplegia, and visual loss. This typicallyresponds to steroids.

Lymphoma of the orbit typically causes eccentricproptosis. CT or MRI typically demonstrates a mass,or masses, located near the orbital apex.

Other orbital masses, generally associated withunilateral proptosis, include metastasis, vascularanomalies, neurofibromas, and retinoblastoma.


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Treatment

With the exception of acute and progressive Gravesorbitopathy (malignant exophthalmos), the disease isself-limited in the majority of patients.

Medical treatment should be the first step inaddressing Graves orbitopathy.

While exophthalmos generally improves withcorrection of hyperthyroidism, this is not always the

case. Surgical treatment of Graves orbitopathy isgenerally delayed until both the status of the orbit andthe thyroid have stabilized for 6 months.


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Treatment The goal of surgery is to enlarge the confining space of the

orbit via removal of 1 to 4 walls of the bony orbit with incisionof the periosteum to allow for prolapse of the orbital softtissues into adjacent spaces.

Theoretically, up to 15 mm of decompression can be achieved

by removing all 4 walls (usually, surgery results in 3-7 mm ofdecompression). However, intractable strabismus andhypoglobus can result from excessive decompression.

Patients must be made aware of the risks associated withdecompression of the orbit. The most common complication

is diplopia. Other potential complications include injury to theoptic nerve or retina from prolonged globe retraction.Retrobulbar hematomaa potential cause of blindness isalso a possibility. Injury to the infraorbital nerve and epistaxismay also occur.


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Surgery

Indications for orbital decompression vary depending

on time course. In the acute or subacute phase of the

disease, surgery is indicated if steroids fail to improve

visual disturbance OR if steroids are required forlong-term maintenance of vision.

. Functional indications for surgery, generally

present in the acute or subacute phase, include

corneal exposure with keratitis, usually in patients

with significant lid retraction. More commonly,

functional indications are related to optic neuropathy


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Sugery

In the late phase, decompression is generallyperformed for cosmesis, which is a relative indication.This should occur only after orbital findings havestabilized for approximately 6 months.

In general, the more advanced the exophthalmos, themore extensive the surgery required to produce evena modest improvement. As a result, very few patientsare satisfied with the initial surgical procedure.

Ideally, orbital decompression is performed first,followed by strabismus surgery and then lidlengthening.


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Orbital Decompression

SUPERIOR ORBITAL DECOMPRESSION

(Naffziger)

MEDIAL DECOMPRESSION (Sewell)

LATERAL DECOMPRESSION (Kronlein)

COMBINED MEDIAL AND INFERIOR

DECOMPRESSION (Walsh-Ogura) ENDOSCOPIC DECOMPRESSION

ORBITAL FAT REMOVAL


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Fat removal orbitaldecompression

This represents an alternative to traditional orbitaldecompressive procedures.

With this procedure, the preoperative CT scan is

helpful in demonstrating the location of orbital fatpockets.

These fat pockets can then be approached via anupper lid crease and subciliary or transconjunctivalincisions. The orbital septum in both upper and lowereyelids must be opened longitudinally and the fatcompartments debulked.


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Excellent hemostasis must be obtained, and injury tothe lacrimal gland in the superolateral quadrant is bestavoided. Trauma to the inferior oblique muscle mustalso be avoided.

As much as 6 mm of proptosis can be corrected withthis technique, which correlates with the removal of 5to 6 ml of fat.

This may be a more useful technique when orbital fatinvolvement is the major underlying problem asopposed to extraocular muscle involvement or opticneuropathy.


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PURPOSE: Retrospective evaluation of 41 proptosisreduction procedures using fat removal orbitaldecompression (FROD) according to a modifiedOlivaris technique.

METHODS: Trans-septal excision of extraconal andintraconal fat was done under the microscope throughthe upper and lower eyelid blepharoplasty approach.Proptosis was measured with a Hertel exophthalmometer.

Eur J Ophthalmol. 1998 Oct-Dec;8(4):246-52


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RESULTS: Mean excision of 7.31 + 1.9 ml (range 3.25-12 ml) of orbital fat reduced proptosis on average by 4.7+ 2.4 mm (range 1-11 mm). Side effects were few,limited only to ocular motility disturbances. There wasno significant effect on visual fileds. A postoperativedrop in IOP was noted in patients with preoperative IOPabove 21 mmHg. Efficient palpebral lengthening can beachieved with combined section of the levator

aponeurosis horns in the upper eyelid, and/or auricularcartilage graft in the lower eyelid.

CONCLUSIONS: FROD reduces proptosis in Grave'sophthalmopathy

Eur J Ophthalmol. 1998 Oct-Dec;8(4):246-52


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Conclusion

The most common cause of bilateral exophthalmos isGraves orbitopathy. The presence or severity of

Graves orbitopathy does not correlate well with the

thyroid status of the patient.

Though Graves orbitopathy is a product of

autoimmune disease, definitive treatment remains

primarily surgical.

Treatment of Graves disease and Graves orbitopathyshould be multidisciplinary.


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Conclusion

Preoperative imaging is vital and shouldinclude both the orbits and the sinuses.

The current surgical treatment of choice isendoscopic orbital decompression or lateraldecompression or both. Every effort should bemade to protect the inferior and medial rectus

muscles and to minimize the extent ofpostoperative diplopia, which remainscommon following orbital decompression.

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