Endocrine orbitopathy

Diffuse idiopathic inflammation of the orbit shows with findings at CT and MRI that are non-specific, with high contrast uptake of inflamed structures, infiltration of orbital fat tissue, and inflammation with edema of intraorbital muscles and tendons. As a differential diagnosis, autoimmune hyperthyroidism (Morbus Basedow, Graves disease, associated with endocrine orbitopathy or EO, see below. Sect. 12.6) does not affect intra-orbital tendons. 

Dysthyroid endocrine orbitopathy (EO) or thyroid eye disease is the most common disorder affecting the orbit, usually presents in middle-aged women, and represents the most frequent cause of unilateral or bilateral proptosis in adults (Mueller-Forell and Pitz 2004 Aviv and Miszkiel 2005). EO is predominantly associated with autoimmune hyperthyroidism, which is also referred to as Morbus Basedow or Grave s disease (Mueller-Forell and Pitz 2004), but the orbitopathy may precede thyroid disease or occur with euthyroid or hypothyroidism (Aviv and Miszkiel 2005). EO is associated with edema of all structures of the orbit. The hallmarks of EO, however, are spindle-shaped edema of the intra-orbital muscles, which leaves out the tendons, and enlargement of the intra-orbital fat tissue (Fig. 12.7) (Mueller-Forell and Pitz 2004 Aviv and Miszkiel 2005). Muscular edema usually is most pronounced in... 

Fig. 12.7a-c. Endocrine orbitopathy (EO) is among the most common causes for proptosis. Axial (a), coronal (b) and sagittal (c) MDCT images of the orbit demonstrate severe bilateral thickening of intra-orbital muscles, which is usually most pronounced in the medial and inferior rectus muscles (arrows), leaves out the tendons, and may result in optic nerve compression at the aperture of the optical nerve canal (curved arrows). Hypertrophy of intra-orbital fat tissue is another feature typical of EO... 

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