Extraocular muscle enlargement with tendon involvement in thyroid-associated orbitopathy

Ben Simon, Guy J.; Syed, Hasan M.; Douglas, Raymond; McCann, John D.; Goldberg, Robert A.

doi:10.1016/j.ajo.2004.01.033

« Previous Next »American Journal of Ophthalmology
Volume 137, Issue 6 , Pages 1145-1147, June 2004

Extraocular muscle enlargement with tendon involvement in thyroid-associated orbitopathy

Guy J. Ben Simon, MD
- Division of Orbital and Ophthalmic Plastic Surgery, Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA
- Inquiries to Guy J. Ben Simon, MD, Jules Stein Eye Institute, 100 Stein Plaza, Box 957006, Los Angeles, CA 90095-7006, USA; fax: 825-9263
Hasan M. Syed
- Division of Orbital and Ophthalmic Plastic Surgery, Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA
Raymond Douglas, MD, PhD
- Division of Orbital and Ophthalmic Plastic Surgery, Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA
John D. McCann, MD, PhD
- Division of Orbital and Ophthalmic Plastic Surgery, Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA
Robert A. Goldberg, MD
- Division of Orbital and Ophthalmic Plastic Surgery, Department of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA

Accepted 2 January 2004.

Abstract

Purpose

To evaluate the configuration of extraocular muscle and tendon enlargement in patients with thyroid-associated orbitopathy (TAO).

Design

Retrospective, noncomparative case series.

Methods

We retrospectively evaluated the preoperative computed tomography (CT) or magnetic resonance imaging (MRI) scans, or both, of 125 consecutive patients with previously diagnosed TAO. Axial CT (n = 88) or MRI (n = 37) slices of the orbits were examined for tendon involvement of enlarged medial or lateral recti muscles. A ratio of tendon to muscle width greater than 0.5 was considered as tendon involvement.

Results

Eight patients (6.4%) with TAO demonstrated tendon involvement on axial CT or MRI. These patients had significantly greater diplopia in primary gaze than patients with no tendon involvement or patients with no muscle enlargement.

Conclusion

The configuration of extraocular muscle enlargement on imaging studies has traditionally been used to differentiate TAO from other inflammatory processes because the tendon is typically spared (fusiform configuration) in TAO. However, we found that the configuration of tendon involvement (cylindrical configuration) can occasionally be noted in TAO and may be more frequently associated with primary gaze diplopia. Tendon involvement does not eliminate the diagnostic possibility of TAO.