Radiographic Analysis of Extraocular Muscle Volumetric Changes Following Orbital Decompression in Thyroid-Associated Orbitopathy: Comparison of Nunery Types 1 and 2.

Hwang, Kyu Yeon; Cho, Won Kyung; Paik, Ji Sun; Yang, Suk Woo

doi:2013.54.1.1

J Korean Ophthalmol Soc > Volume 54(1); 2013 > Article

Original Article

Journal of the Korean Ophthalmological Society 2013;54(1):1-6.
DOI: https://doi.org/10.3341/jkos.2013.54.1.1 Published online January 15, 2013.

Radiographic Analysis of Extraocular Muscle Volumetric Changes Following Orbital Decompression in Thyroid-Associated Orbitopathy: Comparison of Nunery Types 1 and 2.

Kyu Yeon Hwang, Won Kyung Cho, Ji Sun Paik, Suk Woo Yang

Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea. yswoph@catholic.ac.kr

갑상샘눈병증에서 안와감압술 전후 외안근 부피 변화의 영상분석: Nunery 분류법 제1형과 2형 비교

황규연⋅조원경⋅백지선⋅양석우

Department of Ophthalmology and Visual Science, Seoul St. Mary’s Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea

Abstract

PURPOSE
To evaluate the radiographic volume change in extraocular muscles (EOM) following orbital wall decompression for Nunery type 1 and type 2 thyroid-associated orbitopathy (TAO). METHODS: Medical records of 31 orbits in 20 patients undergoing postoperative orbital CT after orbital decompression for TAO were retrospectively reviewed. The patients were divided according to Nunery classifications. A type 1 classification was assigned to patients who had no diplopia and essentially normal versions. A type 2 classification was assigned to patients with restrictive motility loss and diplopia within 20 degrees of the primary position. EOM volumes were determined by the summation of each EOM's cross-sectional areas in the coronal plane of the CT scans and multiplying the sum by the slice thickness. Main outcome measure was a comparison of EOM volume changes between types 1 and 2 TAO and a relationship between EOM volume and change in proptosis. RESULTS: In type 2 TAO, a significant increase in the volume of the medial rectus muscle, lateral rectus, and total EOM was detected postoperatively (p = 0.044, 0.022, 0.049), whereas no significant changes were found in the EOM's volume changes in type 1 TAO. The reduction of proptosis after orbital decompression in type 1 TAO was significantly greater than in type 2 TAO (p = 0.025). A significant positive association was observed between the preoperative EOM volumes and the reduction of proptosis following orbital wall decompression (r = 0.505). CONCLUSIONS: The postoperative EOM volumes following orbital wall decompression was significantly increased in Nunery type 2 patients who had restrictive myopathy.

Key Words: Extraocular muscle (EOM);Nunery;Radiographic;Thyroid-associated orbitopathy (TAO)