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
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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
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Therapy is still primarily directed at manifestations of
the disease in a palliative fashion
Pathophysiology
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
Inferior Orbital Decompression
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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
Inferior Orbital Decompression
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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
Inferior Orbital Decompression
Lateral Orbital Decompression
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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
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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
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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
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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
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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
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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
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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