Author's: Baptista, Luís ¹; Guincho, Joana ¹; Castelhano, Luís ¹; Correia, Filipe ¹; Escada, Pedro ¹

Affiliations: 1 – Otorhinolaryngology Department – Unidade Local de Saúde Lisboa Ocidental (ULSLO);  

ABSTRACT

Thyroid orbitopathy, driven by autoantibodies targeting TSH receptors, leads to increased orbital fat and connective tissue, resulting in proptosis, diplopia, and, in 5-10% of cases, dysthyroid optic neuropathy (DON). DON, characterized by progressive vision loss, requires high-dose intravenous corticosteroids and urgent orbital decompression if initial treatment fails. This case report describes a 60-year-old man with Graves’ orbitopathy that developed DON. Despite treatment with corticosteroids, his vision deteriorated, requiring urgent endoscopic transnasal orbital decompression. Postoperatively, the patient’s visual acuity improved significantly and there were no signs of optic nerve dysfunction. This case reinforces the efficacy of endoscopic transnasal orbital decompression in managing severe thyroid orbitopathy and highlights the importance of a multidisciplinary approach involving Ophthalmology, Endocrinology, and an Ear, nose and throat (ENT) team for optimal patient outcomes.

Keyword's: Graves’ orbitopathy, Endoscopic surgery, Orbital decompression, Dysthyroid optic neuropathy, Diplopia

INTRODUCTION

Graves’ orbitopathy results from the stimulation of orbital fibroblasts by autoantibodies directed at the TSH receptor, which induces lymphocytic infiltration and glycosaminoglycan deposition [1]. This leads to an increase in orbital fat and connective tissue, manifesting as proptosis, diplopia, exposure keratitis and, in 5 to 10% of cases, dysthyroid optic neuropathy (DON) [2].

DON presents with progressive loss of visual acuity, impaired color vision, visual field defects, as well as optic disk swelling/pallor during ophthalmological examination. If not treated appropriately it may result in the complete loss of vision. Its first-line treatment consists of high-dose intravenous corticosteroids, followed by urgent orbital decompression if the response is poor or absent [3]. 

The literature describes several different approaches of surgical decompression of the orbit. More aggressive approaches such as coronal or transantral have generally been abandoned in favor of minimally invasive such as endoscopic, transconjunctival or transcaruncular [4]. The endoscopic approach, by allowing decompression of the medial wall of the orbit up to the orbital apex, offers the best results when there is optic nerve damage [5].

We present the case of a patient with Graves’ orbitopathy diagnosed with DON in whom endoscopic transnasal orbital decompression was performed as a salvage therapy. This case highlights that endoscopic sinus surgery holds significant potential in the management of not only nasal diseases but also conditions affecting neighboring structures, such as the eye.

CASE PRESENTATION

A 60-year-old man was referred to the neurophtalmology clinic for progressive thyroid orbitopathy. Graves’ disease had been diagnosed 8 months earlier after complaints of tremor and weight loss. He was treated with methimazole 10 mg per day and became euthyroid. Additional medications included the combinations of perindopril/amlodipine and metformin/dapagliflozin for pre-existing essential hypertension and diabetes mellitus type 2, respectively. The patient recalled experiencing sporadic blurred vision and double vision predominantly in the mornings, which began 5 months after the diagnosis.

Examination on the neurophthalmology clinic revealed that visual acuity was 9/10 on the right and 8/10 on the left eye. Slit-lamp examination showed exophthalmos, eyelid edema and retraction bilaterally, but more prominent on the left. Proptosis by Hertel exophtalmometry was 21mm on the right eye and 25mm on the left eye. On the left eye the Relative Afferent Pupillary Defect (RAPD) was doubtful and chromatic desaturation was present. Blood tests revealed low thyroid-stimulating hormone, normal free thyroxine and free triiodothyronine levels and elevated TSH receptor antibodies.

The patient started salvage therapy under the EUGOGO protocol with high single doses of intravenous methylprednisolone (1 gram on every second day). After the third dose of corticosteroid the patient complained of worsening vision. Physical examination revealed that visual acuity was 6/10 on the left eye and 8/10 on the right eye. On the left eye, Relative Afferent Pupillary Defect (RAPD) and chromatic desaturation were both present. For this reason, Ophthalmology contacted the ENT team to perform an urgent orbital decompression.

The surgical procedure included the following steps:

1. The patient was in the supine position, under general anesthesia and with eyes uncovered;
2. A wide maxillary sinusotomy was performed to give access to the orbital floor;
3. A total ethmoidectomy and wide sphenoidotomy were performed to avoid future obstructive disease from prolapsed orbital fat;
4. The medial orbital wall (lamina papyracea) was removed while preserving the underlying periorbita;
5. The orbital floor was removed up to a lateral boundary defined by the infraorbital nerve canal;
6. A modified inferomedial orbital strut was left in place;
7. The periorbita was incised from posterior to anterior and orbital fat prolapsed into the ethmoid and maxillary cavities;

Figures 1 and 2 correspond to photographs of this procedure, which was completed without any incidents.

In the reevaluation after surgery the patient reported improvement in vision. Visual acuity was 10/10 on the right and 8/10 on the left. RAPD and chromatic desaturation were not present.