Surgery for Exophthalmos

Surgery for Exophthalmos

Stephanie Cordes, MD

Faculty Advisor: Karen Calhoun, MD

The University of Texas Medical Branch

Department of Otolaryngology

Grand Rounds Presentation

April 26, 2000

Introduction

Exophthalmos is a condition of altered thyroid

metabolism that causes protein depositions within the

extraocular muscles

Graves’ disease is a multisystem disorder

characterized by:

– hyperthyroidism associated with diffuse hyperplasia of the

thyroid gland

– infiltrative ophthalmopathy leading to exophthalmos

– infiltrative dermopathy with localized pretibial myxedema

Therapy is still primarily directed at manifestations of

the disease in a palliative fashion

Pathophysiology

Many patients are euthyroid at the time the eye

symptoms appear, although further testing usually

reveals dysthyroidism

Treatment of the thyroid disease does not prevent the

later development of orbital manifestations or

ameliorate eye symptoms already present

Current theory involves autoreactive T cells which are

reactive to the TSH receptors

Humoral immunity produces antibodies to the TSH

receptor that are stimulatory, resulting in

hyperthyroidism

Pathophysiology

Extraocular muscles are the site of the most clinically

evident changes in these patients

Muscles are enlarged and there is an associated

intense proliferation of perimysial fibroblasts and

dense lymphocytic infiltration.

Retrobulbar fibroblasts secrete glycosaminoglycans

which causes interstitial edema, these cells can also

produce MHC class II molecules, heat shock

proteins, and lymphocyte adhesion molecules

Fibroblast antigen may be similar to all or part of the

TSH receptor, representing a shared thyroid-eye

antigen

Pathophysiology

Graves’ Ophthalmopathy More than 50% of patients with Graves’ disease have

eye complaints, only 5% warrant intervention

Lid retraction is the orbital symptom that is most likely

to regress without treatment

Proptosis usually peaks 4 to 13 months after the

onset of the disease, and regression in the range of 3

to 7 mm occurs in half of the patients over the

ensuing 1 to 3 years

Eye involvement is bilateral in the majority of patients

although 5% to 14% will have unilateral disease

Major asymmetry of eye involvement is common,

Graves’ remains the most common etiology of

unilateral proptosis in adults

Classification ATA class I - involves lid lag and appearance of a

“stare”

ATA class II - increased intraocular pressure leads to

chemosis, excessive lacrimation, periorbital edema,

and photophobia

ATA class III - volume of orbital contents increases

causing proptosis (increase of 4ml leads to 6mm

proptosis)

ATA class IV - extraocular muscles become

dysfunctional resulting in decreased ocular mobility

and diplopia

ATA class V - corneal exposure, desiccation, irritation

and ulceration

ATA class VI - most severe, involves damage to the

optic nerve leading to impairment of vision

ATA Classification

Patient Evaluation

Most patients are initially evaluated by a medical

specialist

Full endocrinology work up is essential

Some patients complain of symptoms of

hyperthyroidism

Any patient with unilateral or bilateral exophthalmos

should be considered to have thyroid disease

Increased total and free T3, total and free T4, reverse

T3 uptake, TRH, and thyroid stimulating

immunoglobulin

Most patients can be shown to have some amount of

thyroid dysfunction

Physical Examination

Can confirm the upper and lower eyelid retraction,

proptosis, and other physical signs of

hyperthyroidism

Pathognomonic sign for Graves' ophthalmopathy is

hyperemia over lateral rectus muscle

Complete ophthalmologic exam should be performed

Serial eye exams are required to monitor disease

progress and response to therapy, they should

measure soft tissue changes, document proptosis,

intraocular pressure, ocular motility, strabismus, and

visual function

Complete head and neck exam including thyroid

status

Physical Examination

Radiology CT scans of the orbit are essential if surgery is

planned

Findings include 2 to 8 fold increase in the

extraocular muscle bodies sparing the tendinous

portions

Inferior and medial rectus muscles are most

commonly involved

Ultrasound can demonstrate thickening of all the

extraocular muscles - used to monitor the response

to therapy

T2 weighted images on MRI can show active

inflammation in the orbit, no bony detail

Scans should include paranasal sinuses and rule out

any significant sinus disease

CT Scan

Differential Diagnosis

Most common diagnosis to consider in bilateral

proptosis is pseudotumor cerebri

Lymphoma of the orbit can produce proptosis

Metastatic tumor, vascular anomaly, neurofibroma,

and retinoblastoma can all cause unilateral proptosis

Most other disease entities have only superficial

similarities to Graves’ ophthalmopathy and can be

ruled out

Keep a high index of suspicion if the diagnosis is to

be made in a timely fashion

Differential Diagnosis

Management

Multispecialty team approach is

recommended because of multiple organ

systems involved

Team should include - endocrinologist,

radiologist, nuclear medicine physician,

radiation therapist, ophthalmologist,

otolaryngologist, and neurosurgeon

Both medical and surgical management

options for the treatment of Graves’ disease

Medical Management All patients require management of their

hyperthyroidism

Management usually centers on the suppression of

the thyroid activity, after euthyroid status is achieved

for 6 months the orbital status usually stabilizes

1% to 2% of patient will develop a deterioration in the

visual status and the treatment of choice is high dose

steroids

Adjunctive treatment includes lubricants, artificial

tears, moisture chambers, and taping retracted

eyelids if necessary

Low dose radiation therapy has been used 20Gy in

10 fractions for 2 weeks - patients early in disease

process most likely to benefit

Surgical Management Preoperative counseling centers on risks of vision

motility disorders and failure to achieve a satisfactory

result

Considered for two stages of dysthyroid

exophthalmos

In the acute or subacute stages, steroids are used, if

the patient fails to regain visual acuity with the

steroids then surgical decompression is indicated

In the late stage, when proptosis and lid retraction is

evident then cosmetic decompression is indicated

Usual functional indications for decompression are

decreasing visual acuity, visual field defects,

abnormal visual-evoked potentials, and disc edema

as well as corneal exposure with keratitis not

responsive to medical management

Surgical Approaches

Superior Orbital Decompression Involves unroofing the entire superior orbital wall by a

craniotomy

Neurosurgeon exposes the orbit by a frontal

craniotomy

After the optic nerve has been identified, the bony

roof of the orbit is removed from just anterior to the

optic foramen to the anterosuperior orbital rim

Superior periosteum is then incised in an H-shaped

fashion and the orbital fat allowed to herniate into the

cranial vault

Titanium mesh and pericranial flap are used to close

the defect

This approach is used for only very severe cases due

to associated morbidity

Medial Orbital Decompression

Approached through the standard external

ethmoidectomy incision or through a coronal

forehead approach

Ethmoidectomy approach displaces the medial

canthal tendon and elevates the lacrimal sac out of

its fossa

Anterior and posterior ethmoid arteries are identified

and clipped

A complete ethmoidectomy is performed removing all

the mucosa bearing septa

Posterior ethmoid cells are removed back to the

posterior ethmoid plate

Medial orbital periosteum is incised longitudinally

Medial Orbital Decompression

Inferior Orbital Decompression

Creates a large inferior orbital floor blow out fracture

while sparing injury to the infraorbital nerve

Procedure can be done through subciliary,

transconjunctival, or Caldwell-Luc incision, but some

authors prefer to combine the approaches for better

visualization

A skin-muscle flap is elevated in the lower eyelid and

the orbital rim is visualized

The periosteum is incised and elevated from the

orbital floor for approximately 4 cm

Caldwell-Luc incision is made sublabially and a wide

antrostomy is formed


Course of the infraorbital nerve is visualized and the

bone medial and lateral to the nerve is removed

The remainder of the floor is removed under direct

visualization, 3 cm anteroposterior range for bone

removal is safe, medially removed to lacrimal fossa

and laterally removed to the zygoma

Periorbita is incised longitudinally, number of

incisions determined intraoperatively, 4 to 6 usually

adequate

Fat herniates into the defects on either side of the

nerve

Middle meatal ostium enlarged to provide for

ventilation and drainage of the sinus


Sinus is then irrigated free of blood and Penrose

drain inserted

Incisions are closed in layers, avoid closing the soft

tissue layer of the lower eyelid to prevent ectropion

Procedures associated with the paranasal sinuses

should use perioperative antibiotics

Inferior decompression alone gives a mean of 3.5

mm reduction in proptosis, whereas combined antral

and ethmoid decompression has been shown to

produce a mean of over 5 mm reduction in proptosis


Lateral Orbital Decompression Approaches include coronal, direct rim incision, or

extended lateral canthotomy

Periosteum over the lateral orbital rim is exposed and

incised widely

It is elevated from the orbital side of the infratemporal

fossa for approximately 3 to 3.5 cm posteriorly

Lateral orbital rim can be cut and mobilized leaving

its attachment to the periosteum to assist with closure

Much of the lateral orbital wall can be removed

(about 2.5 to 3.5 cm)

Periorbita is incised and fat teased out into newly

created space

Lateral Orbital Decompression

Endoscopic Orbital

Decompression Medial and medioinferior floors of the orbit can be

removed through a transnasal approach

Can not decompress the orbit lateral to the

infraorbital nerve or extensively open the periorbita

for extrusion of fat

May require a septoplasty for exposure

Uncinate process is taken down and a large

antrostomy is created opening superiorly to the level

of the orbital floor and inferiorly to the roof of the

inferior turbinate

Middle turbinate is routinely resected

Ethmoidectomy is performed and the anterior and

posterior ethmoid arteries are identified

Endoscopic Orbital

Decompression

Medial orbital wall is expose from the fovea

ethmoidalis to the anterior face of the sphenoid sinus

Trocar inserted through the canine fossa can allow

visualization through the puncture while working

through the nose

Infraorbital nerve is identified and mucosa elevated

from the roof of the maxillary sinus

Lamina papyracea is fractured and removed to the

level of the ethmoid arteries, bone removal is carried

superiorly to within 2 mm of the fovea ethmoidalis,

posteriorly to the face of the sphenoid, and laterally to

the nerve

Endoscopic Orbital

Decompression

A buttress of bone is preserved anteriorly at the

juncture of the inferior and medial orbital walls to

avoid excessive inferior displacement of the globe

Orbital periosteum is incised superiorly in a posterior

to anterior direction with a sickle knife taking care to

avoid excessive penetration with the knife

Orbital fat protrudes into the ethmoid cavity

Silastic splint is placed to avoid postoperative

adhesions and packing is not used

Endoscopic approach allows a mean reduction of

proptosis of 3 mm

Endoscopic Orbital

Decompression

Orbital Fat Removal

Recently proposed as alternative to

decompression surgery

Utilizes subciliary and upper lid crease

incisions

Fat compartments are debulked from upper

and lower lids similar to a blepharoplasty

Must achieve excellent hemostasis, usually

with bipolar cautery

As much as 6 mm of proptosis reduction can

be achieved with this approach

Treatment Options

Complications If allowed to progress unchecked, patients can

develop progressive optic neuropathy which can lead

to blindness

Major complications of medical management is the

failure to recognize a medical failure and to delay

surgery

Steroid therapy complications - gastric ulcer, irritable

personality, reactivation of dormant infection

Radiation complications - cataracts, pituitary

suppression, and optic fibrosis

Decompression surgery - diplopia, unsatisfactory

result, corneal abrasion, excessive retraction on the

globe, retrobulbar hematoma, injury to infraorbital

nerve, ectropion, retinal hemorrhage (diabetic

patient), and orbital cellulitis

Complications

Emergencies

Retrobulbar hematoma, retinal vascular occlusion,

and corneal ulcer are the major sight threatening

emergencies

Retrobulbar hematoma is treated with opening of skin

incisions and evacuating the clot

Retinal vascular occlusion is related to increased

intraocular pressure and is an ophthalmologic

emergency

Patient should be maintained on appropriate eye

protection to avoid corneal ulceration

Patient should be warned to seek immediate medical

attention for increasing pain in the eye or for

decreasing vision

Documents

Surgery for Exophthalmos