Graves’ Ophthalmopathy Imaging Evaluation

Abstract

Graves ophthalmopathy GO , known as Graves orbitopathy or thyroid eye disease TED , is an autoimmune disorder and the main extrathyroidal expression of Graves' disease GD . GO occurs mainly, but not exclusively, in patients with Graves disease up to % of GD patients have clinically apparent ophthalmopathy . The major clinical risk factor for developing thyroid eye disease is smoking. Moreover, radioactive iodine used to treat hyperthyroidism can worsen GO. There is an age-specific and gender-related distribution of GO, and the annual incidence is . % for women and . % for men but this largely reflects the increased incidence of GD in women [ ]. In addition to GD, thyroid eye disease can also be seen in chronic autoimmune thyroiditis, albeit is far less common and occurs in % of these patients [ ]. "lthough the link between GD and GO is still not totally clear, the close association between onset of GD and the development of GO suggests that both disorders would have common pathogenic mechanisms [ ]. The ocular involvement of GD is explained by the expression of receptor for thyroid-stimulating hormone TSH-R present not only in the thyroid follicular cells but also in adipocytes, and fibroblasts located in the orbit, and lymphocytes infiltrating orbit tissues [ ]. Likewise, the signs and symptoms of GO occur due to inflammatory reaction and subsequent fibrosis of the orbital components, including orbital connective tissue, and the extraocular muscles [ ]. Inflammatory cell infiltration of extraocular muscles is associated with increased secretion of glycosaminoglycans and osmotic retention of water. The muscles become enlarged, sometimes up to eight times their normal size, and may compress the optic nerve. Subsequent degeneration of muscle fibers eventually leads to fibrosis, which exerts a tethering effect on the involved muscle resulting in the muscle dysfunction and ophthalmoplegia. Infiltration of interstitial tissues, orbital fat and lacrimal glands with lymphocytes, plasma cells, macrophages and mast cells along with accumulation of glycosaminoglycans and

Evaluation of Proptosis: A Primer

“…In TED, the muscle bellies are characteristically fusiform with sparing of the tendons. 6,16,[33][34][35] The wide range of orbital pathologies causing proptosis may prove to be diagnostic and management challenges. Imaging techniques, such as magnetic resonance imaging (MRI) provide high-resolution soft tissue details leading to better lesion characterization.…”