Surgery for Exophthalmos

1. Surgery for Exophthalmos Stephanie Cordes, MD Karen Calhoun, MD

2. 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

3. 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

4. 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

5. Pathophysiology

6. 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

7. 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

8. ATA Classification

9. 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

10. 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

11. Physical Examination

12. 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

13. CT Scan

14. 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

15. Differential Diagnosis

16. 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

17. 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

18. 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

19. Surgical Approaches

20. 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

21. 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

22. Medial Orbital Decompression

23. 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

24. Inferior Orbital Decompression 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

25. Inferior Orbital Decompression 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

26. Inferior Orbital Decompression

27. 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

28. Lateral Orbital Decompression

29. 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

30. 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

31. 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

32. Endoscopic Orbital Decompression

33. 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

34. Treatment Options

35. 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

36. Complications

37. 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