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

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.

The Clinical Phenotype of Thyroid-Associated Orbitopathy related to Underlying Thyroid Status

PURPOSE: Thyroid-Associated Orbitopathy (TAO) presents with highly variable clinical characteristics. We hypothesize that the underlying thyroid status predisposes a patient to different clinical characteristics of TAO. METHODS: We retrospectively studied the clinical data of 385 patients from the New York area who were referred to our clinic and diagnosed with TAO from Jan 1990 to Dec 2000. We divided the 385 patients into three groups: Graves' hyperthyroid, euthyroid, and hypothyroid, and analyzed them statistically. RESULTS: Three hundred thirty-one (86%) patients were hyperthyroid, 25 (6.5%) were euthyroid, and 29 (7.5%) were hypothyroid. The average age of TAO presentation in each group was 46.7, 46.1, and 49.9 years, respectively. The female-male ratio in each group was 5.25, 3.17, 13.5:1, respectively (p>0.05). The average time from thyroid disease to TAO in the hyperthyroid and hypothyroid groups was 16.6 and 38 months, respectively (p<0.05). The hyperthyroid group had more proptosis (76.1 vs. 41.4%, p=0.0001<0.05) than the hypothyroid group. CONCLUSIONS: TAO has different clinical characteristics depending on thyroid status. The hyperthyroid group has a short disease interval and more severe clinical course of TAO than the hypothyroid group.

The Risk Factors for Severe Thyroid-Associated Orbitopathy

PURPOSE: To determine risk factors for severe Thyroid-Associated Orbitopathy (TAO). METHODS: We retrospectively studied the clinical data of 385 patients of the New York City area diagnosed with TAO from January 1990 to December 2000. We reviewed clinical characteristics and tried to identify several risk factors. The statistical analysis was applied to the collected data. RESULTS: Men more frequently had proptosis, restrictive myopathy, and optic neuropathy than women. Patients older than 50 years presented more frequently with proptosis, restrictive myopathy, and optic neuropathy than younger than 50 years. Patients with a family history of thyroid disease had similar clinical characteristics compare to those without family history. Smokers more often had proptosis, restrictive myopathy, and compressive optic neuropathy than nonsmokers. Patients who had received radioactive iodine (RAI) treatment were older, and were more frequently smokers. If patients were smokers and treated with radioactive iodine treatment, they were more likely to have proptosis, restrictive myopathy, and compressive optic neuropathy than if not treated with radioactive iodine. However, the RAI treatment did not seem to be associated with severe characteristics of TAO in non-smokers. CONCLUSIONS: The risk factors for severe TAO are: male, age older than 50, smoking, treated with RAI in smokers.

The Epidemiologic and Clinical Characteristics of Thyroid-Associated Orbitopathy

PURPOSE: To determine the epidemiologic and clinical characteristics of thyroid-associated orbitopathy (TAO). METHODS: We retrospectively studied the clinical data of 385 patients from the New York City area diagnosed with TAO from January 1990 to December 2000. The total cases were divided into male and female groups and age-adjusted relative incidence rates were obtained to plot the incidence curve and clinical characteristics. Statistical analysis was applied to the collected data. RESULTS: The average age of patients with TAO was 46.3 years for females and 50.1 years for males. The female-male ratio was 5.31:1. In 23.3% of patients, the diagnosis of TAO was made simultaneously with their thyroid disease. In 75% of cases, the diagnosis was made within 18 months of the presentation of thyroid disease. Soft tissue involvement was noted most frequently in 311 (80.8%), eyelid retraction in 306 (79.5%), proptosis in 278 (72.2%), restrictive myopathy in 234 (60.8%), and compressive optic neuropathy in 43 (11.2%) of 385 patients. CONCLUSIONS: TAO has variable and different epidemiologic and clinical characteristics according to sex and age.