Atlas of Ophthalmology

Orbital Apex Syndrome in Endocrine Orbitopathy (Colour Photo, VEP, MRI, VF, OCT)

Orbit -> Non-Infectious Inflammatory Disease
Patient: 25 years of age, female, BCVA 0.8 at OD, 0.6 at OS, diplopia, IOP 30 mmHg at OD, 24 mmHg at OS. General medical history: hypothyreosis in the past, now regular TSH and TRH, ANCA negative. Ocular Medical History: impairment of vision at both eyes, conjunctival chemosis, desaturation of color vision. After therapy with steroids (400 mg) over 5 days significant improvement of visual fields, VEP amplitude and latency. Main complaint: diplopia and conjunctival chemosis. Purpose: to present findings of an orbital apex syndrome in Graves disease. Methods: Facial Colour Photography, Visual Evoked Potential, Magnetic Resonance (MR) Imaging , visual field 90°, OCT optic nerve head. Findings: Facial Colour Image: strabism, conjunctival chemosis. VEP: impaired amplitude and latency at OD. Magnetic resonance (MR) imaging : at both eyes apical orbital crowding with enlargement of of extraocular muscles, spindle like spreading of the rectus muscles without involvement of the tendon, compression of the optic nerve in the orbital apex (crowded orbital apex syndrome), and absence of any space occupying intraorbital process. Visual field 90°: peripherial scotoma at OD, regular field at OS OCT optic nerve head: showing no edema of optic nerve head of OD. Discussion Endocrine orbitopathy (EO) or Graves' orbitopathy (GO) represents the most frequent extrathyroidal stigma of Graves disease. EO (GO) is a chronic autoimmune condition involving the orbital contents, including extraocular muscles, periorbital connective-fatty tissue and lacrimal gland. The increase of fat tissue and the enlargement of extraocular muscles leads to proptosis and diplopia. In severe cases EO (GO) leads to optic neuropathy, caused by compression and stretching of the optic nerve. The congestion and the pressure of the enlarged muscles, constrict the nerve and can lead to reduced sight or loss of vision. Neigel et al. (1) reported that dysthyroid optic neuropathy is an insidious disease; when compared with the usual Graves' orbitopathy patient. Asymmetrical extraocular muscle restriction and vertical tropias were more frequent in the optic neuropathy group. They found, that the most sensitive indicator of optic nerve dysfunction appeared to be visual-evoked potentials and color vision. These findings should alert the clinician to a more aggressive approach to these patients. Imaging and functional nerve evaluation are mandatory in all cases of EO. Müller-Forell W et al. (2) suggested, that neuroimaging plays an important role in the differential diagnosis of patients with GO. Orbital imaging is required in unclear or asymmetric proptosis, in suspected optic neuropathy. Magnetic resonance (MR) imaging show the actual objective morphological findings. Literature: (1) Neigel JM, Rootman J, Belkin RI, Nugent RA, Drance SM, Beattie CW, Spinelli JA. Dysthyroid optic neuropathy. The crowded orbital apex syndrome. Ophthalmology. 1988 Nov;95(11):1515-21. (2) Müller-Forell W, Kahaly GJ. Neuroimaging of Graves' orbitopathy. Best Pract Res Clin Endocrinol Metab. 2012 Jun;26(3):259-71.

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