Graves Disease, Orbital Decompression

Article Author:
Amanda Gibson
Article Editor:
Craig Czyz
Updated:
10/27/2018 12:31:46 PM
PubMed Link:
Graves Disease, Orbital Decompression

Introduction

Thyroid eye disease causes orbital congestion and proptosis due to extraocular muscle and orbital fat enlargement with varying degrees of fibrosis. These anatomical alterations can lead to compressive optic neuropathy, exposure keratopathy, and ocular motility disorders. Treatment of proptosis from thyroid eye disease consists of orbital decompression, taking advantage of the adjacent sinus spaces to expand orbital volume. The amount of decompression required is determined on a case by case basis based on patient presentation. For example, in cases of moderate to severe proptosis, medial wall, lateral wall and floor decompression can be done, taking advantage of the adjacent ethmoid sinuses and maxillary sinus and orbital trigone, respectively.

Anatomy

Medical wall decompression can be done via a transcaruncular approach while a transconjunctival approach can be performed to access the orbital floor. Lateral wall decompression involves removing the bone of the deep lateral orbital wall, known as the trigone. Alternatively or additionally, the inner surface of the super and/or lateral walls can be thinned using a burr.

Indications

Compressive optic neuropathy, exposure keratopathy, and proptosis are key indications to consider orbital decompression in general. Three wall decompression can be of benefit in patients with moderate to severe symptoms including compressive optic neuropathy.

Contraindications

Patients who are systemically unstable for a surgical procedure or who are unwilling to accept the potential complications of surgery. Relative contraindications can include a history of chronic sinusitis, orbital infection, immunocompromise, bleeding disorders, and atretic sinuses.

Equipment

Equipment will vary depending on the approach and procedure.

Preparation

Complete ophthalmic evaluation including dilated fundus exam. Orbital imaging (CT/MRI) for evaluation of anatomy and disease status. Routine preoperative history and physical for surgical clearance should include evaluation of thyroid function and acetylcholine receptor antibody testing in selected cases.

Technique

General endotracheal anesthesia is administered. A mixture of 2% lidocaine with 1:100,000 epinephrine and .75% Marcaine in a 1:1 is injected into the caruncle and inferior conjunctiva via a transconjunctival approach. The patient is then prepped and draped in a standard sterile fashion suitable for oculofacial surgery.

Place a corneal shield. A lid splitting incision starting at the lateral canthus is performed with a No. 15 Bard-Parker blade. Cutting electrocautery is used to incise the periosteum of the lateral orbital rim. A Freer elevator is used to free the periosteum from the underlying bone of the external lateral orbital rim. The temporalis muscle and fascia are separated from the lateral orbital rim with a No. 9 elevator. A similar maneuver is performed to free the periorbita from the intra-orbital lateral orbital rim.

Attention is then placed the orbital floor where a Desmarres retractor is used to retract the lower lid while a Jaeger lid plate is used to protect the globe. Cutting electrocautery was used to dissect through the conjunctiva, lid retractors, and inferior orbital rim periosteum. A Freer elevator was used to free the orbital floor periosteum from the underlying orbital floor. Attention is then placed on the medial wall via a trans-caruncular approach. Westcott scissors are used to create a surgical plane between the caruncle and plica semilunaris. Blunt dissection with Steven scissors is directed to the posterior lacrimal crest, and a Freer elevator is used to open the medial periosteum. A Freer elevator is then used to free the periosteum from the underlying medial wall. A malleable retractor is used to retract the orbital contents and expose the subperiosteal plane. The subperiosteal dissection is continued until the lamina papyracea of the medial wall is visualized, and the appropriate amount of medial wall is exposed. Once exposure of the medial wall and the orbital floor is complete, attention is placed back to the lateral wall.

An oscillating saw is used to create an osteotomy at the superior and inferior lateral wall margins. Kocher clamps are used to remove the lateral orbital wall carefully, and cutting electrocautery is used to separate this wall from the underlying temporalis muscle and fascia. Kerrison rongeurs and a burr (piezoelectric bone saw/burr) are used to remove bone from the deep lateral wall. Care is taken to avoid any CSF leak. Bone wax is used for hemostasis. Attention is placed back to the orbital floor.

An osteotome and mallet are used to create a bone window through the posterior medial orbital floor. The bone of the orbital floor is removed with a pituitary forceps and up biting Kerrison rongeurs. Care is taken to avoid the infraorbital nerve bundle and orbital strut. Once an adequate orbital floor decompression is performed, oxymetazoline is irrigated through the area for hemostasis. Attention is then placed on the medial wall.

A Freer elevator is used to fracture the medial orbital wall. The bone of the medial orbital is removed with a (pituitary/Takahashi) forceps. Underlying ethmoid air cells and mucosa are also removed. Once adequate medial bony decompression is performed, the area is irrigated with oxymetazoline for hemostasis.

A No. 12 Bard-Parker blade is used to incise the periorbita allowing orbital fat to prolapse forward. A malleable retractor is placed as counter-traction in the subperiosteal plane while gentle pressure is placed on the globe allowing orbital contents to prolapse into the decompressed medial orbit.

Attention is placed back to the lateral orbit where the periorbita is incised inferior to the lateral rectus to allow orbital fat to spill forward. The bone flap is thinned with a burr and then replaced with a 4-0 prolene suture through predrilled holes or a low profile curvilinear plate with screws.

The trans-caruncular incision is closed with 6-0 plain gut suture in a buried interrupted fashion. The transconjunctival incision is not closed to prevent postoperative lid retraction. The lateral lower lid is secured to the common canthus and lateral orbital rim with 5-0 vicryl suture. The deep subcutaneous tissue of our lid splitting incision is closed with 5-0 vicryl suture in a buried interrupted fashion. The skin is closed with 6-0 plain sutures in a running fashion.

An ophthalmic antibiotic ointment is placed on the ocular surface after the corneal eye shield is removed. The patient is extubated and taken to the recovery area in stable condition.

Complications

Possible complications include:

  • Orbital hemorrhage
  • Orbital compartment syndrome
  • Optic nerve injury
  • Infection
  • Diplopia
  • Restricted motility
  • Subconjunctival hemorrhage
  • Vision loss
  • Globe dystopia
  • Globe rupture
  • Hypoesthesia (V2)
  • Eyelid retraction or ptosis
  • Vitreous hemorrhage
  • Retinal detachment
  • Cerebrospinal fluid leak
  • Lacrimal drainage system injury
  • Keratopathy
  • Scarring
  • Lid laxity/malposition
  • Canthal angle distortion

Clinical Significance

Thyroid eye disease (TED) is an autoimmune, inflammatory disorder associated most commonly with Graves hyperthyroidism. The most common clinical feature of TED is eyelid retraction, and TED is the most common cause of unilateral or bilateral proptosis. TED is associated with hyperthyroidism in 90% of patients, but euthyroid and hypothyroid disease states can also result in TED. About 30% of patients with Graves hyperthyroidism have TED at the time of diagnosis or will develop TED in the future, and the severity of the disease does not necessarily parallel serum levels of T4 or T3. Female gender and smoking are associated with increased risk and severity of TED, respectively. Decreased vision due to optic nerve compression, present in approximately 2% of all patients with TED, requires urgent orbital decompression.