Thyroid associated orbitopathy

Case contributed by Dr Bruno Di Muzio

Presentation

Thyrotoxicosis.

Patient Data

Age: 80
Gender: Female
CT

CT Orbits

CT of the orbits demonstrates marked fusiform thickening of the inferior rectus, medial rectus and superior rectus muscles bilaterally. The result is proptosis. 

Case Discussion

Thyroid associated orbitopathy is the most common cause of proptosis in adults and is most frequently associated with Graves disease.

CT is the most commonly used modality due to its widespread availability and rapid image acquisition. Contrast, although ideal, is not necessary as the natural contrast between orbital fat and muscle allows for adequate delineation of the orbital content, as it is possible to check on this case.

The order of extraocular muscle involvement can be remembered by the mnemonic I'M SLOW, and bilateral (76-90%) and symmetric (70%) involvement is typical. The tendon is typically spared (although it can be involved in acute cases) with the swelling largely confined to the muscle belly. 

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Case information

rID: 30505
Case created: 14th Aug 2014
Last edited: 1st Sep 2015
System: Head & Neck
Inclusion in quiz mode: Included

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